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Edinburgh Rhododendron Monographs

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Introduction

The Royal Botanic Garden Edinburgh has a history of research into the genus Rhododendron stretching back over 100 years. The legacy of this work is a herbarium that contains many type specimens, an amazing living collection and many publications covering the whole genus. A large amount of the written work on Rhododendron was created just before the digital age and so is only available on paper and spread across many separate publications. An example of this is what could be called "The Edinburgh Rhododendron Monograph". It covers almost a thousand species and was published over 26 years in seven separate publications across two journals and a book. It is not available or indexed in a single form anywhere.

In 2011 I was awarded a Encyclopedia of Life Rubenstein Fellowship to extract the species descriptions from these publications and make them available within EOL. On completion of this work I had a database filled with information about rhododendrons and decided to make it available in an electronic form. This publication is the result of exporting the data from the database.

You can hide this introductory text by clicking on the [-] on the top right.

Finding and Filtering

All the species descriptions are contained in this single HTML page in alphabetical order. Once the page has loaded in your web browser you should be able to use the browser's search function to find species and characteristics.

In addition to searching there is a simple filtering mechanism which will hide all species apart from those that appear to have certain characteristics. You can show and hide the filter by clicking on the links on the right.

Scope of Material

What is presented here does not contain the full texts from the source publications and is not meant as a replacement for them. All keys are omitted. All subgeneric, section, subsection, group and series descriptions and comments are omitted. All notes on cultivation and horticultural value have been omitted. There are no images (maps, diagrams graphs). What remains are the species, subspecies and variety descriptions along with notes on distribution, habitat and nomenclature.

The reader is referred to the source publications for the full text on anything not contained here. Each species description is accompanied by a full citation to the appropriate source publication.

Note on Quality

This is not a 'proper' publication in that it has not been edited or proof read. The text is of varying quality and contains errors. The reader should be aware of this and is expected to interpret the text on this understanding.

A major source of errors is the quality of the Optical Character Recognition (OCR) of the text scanned in the originals. The two source publications from the "Notes from the Royal Botanic Garden Edinburgh" have been scanned at high quality and should have fewer errors than the publications from "Edinburgh Journal of Botany" that were scanned manually. The most recent publication, George Argent's book on vireyas, was kindly made available in electronic form and so has not been through the OCR process.

A second source of errors is the tagging of the original text into a set of uniform fields for all species. This was done partially automatically and partially by hand with the possibility of errors being introduced at both stages. Sometimes the format of the original treatment does not fit a standard pattern and has had to be adapted.

A third class of error is systemic. This publication is a flat list of species descriptions extracted from a hierarchical set of taxon descriptions with no attempt to reconcile the fact that some of the characteristics of the species may only have been mentioned in higher level taxa in the source publication.

A final major source of errors could be termed the "Rumsfeld Errors" - the unknown unknowns. There may be sources of error that are unknown at this time.

In summary: This data is published on the understanding it would be more useful if it were available with errors than not available at all.

Further Work

This publication is a snap shot taken at the end of a project. There are currently no resources available for further development of this particular work although curation and research on Rhododendron at the Royal Botanic Garden Edinburgh continues.

Source Publications

License

This work is licensed under a Creative Commons Attribution 3.0 Unported License. You can freely distribute and modify it as long as you give full attribution to its source.

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Rhododendron aberconwayi Cowan

Shrub, 1.5-2.5m. Leaves elliptic, thick and coriaceous, 3-6 x 1.1-2.2cm, c.3 x as long as broad, apex acute, base cuneate, margin strongly recurved, not undulate, glabrous when mature, with red punctate hair bases overlying the veins beneath; petioles 0.5-lcm, papillate. Inflorescence 6—12-flowered, dense; rhachis c.5mm; pedicels 20—30mm, sparsely hairy and stipitate-glandular. Calyx c.lmm, sparsely hairy, glandular-ciliate. Corolla open-campanulate, lacking nectar pouches, glabrous within, white to pale rose, with purple flecks, 28-35mm. Ovary and style glandular throughout. Capsule 18-20 x c.8mm.

Habitat: Mountain summits

Distribution: China (NE Yunnan)

Notes

Material seen in Kunming from NE Yunnan differs from the type in having rufous-tomentose perulae but is otherwise a good match. Lo Shiueh of McLaren is assumed to be Luoxue in NE Yunnan though this is not certain.

A distinctive species, probably allied to R. annae and R. araiophyllum.

Nomenclature

Type: China, Yunnan, Lo Shiueh Mt, vi 1937, McLaren 'LP 33 (holo. E; iso. BM).

Flags

Occurs in Countries: CN Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: purple, rose, white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):293

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Rhododendron abietifolium Sleumer

Shrub or small tree to 3m. Twigs rounded, green, finely covered in small brown scales, quickly glabrescent; internodes 1–4cm. Leaves in loose pseudowhorls 10–20 together. Blade 18–32 x 4–6mm, narrowly elliptic to linear, often slightly broader in the distal ½; apex broadly pointed; margin entire, strongly recurved, often completely rolled when dry; base tapering; sparsely scaly and quickly glabrescent above, sparsely but more persistently scaly below. Scales sub-circular or shallowly lobed, often with large centres. Mid-vein deeply impressed above, thickly prominent between the revolute parts of the lamina beneath; lateral veins obscure. Petiole 3–8 x 1–1.5mm, grooved above, laxly scaly. Flower buds to 10 x 7mm, ovoid-conical, with the erect subulate points of the bracts standing out, dark-red. Outer bracts keeled, apiculate, inner ones ovate with subulate acumen, the margins densely scaly, minutely hairy or glabrous outside. Bracteoles c.10 x 0.5mm, linear, glabrous, irregularly incised distally. Inflorescence of 2–4-flowered open umbels. Flowers half-hanging to hanging, pink with a violet tinge, without scent. Pedicels 16–20 x c.1mm, densely patently long-hairy, laxly scaly with fragile scales. Calyx c.3mm in diameter, disc-like, weakly angled, sometimes becoming reflexed, patently hairy outside and with a few scales. Corolla 20–25 x 30–34mm, broadly tubular below, sub-campanulate, dilated towards the mouth; tube 18–20 x 6–8 x 9–10mm, sub-densely covered with soft, white, patent hairs and almost without scales, although often with small clusters of scales at the lobe junctions; lobes 13–15 x 8–10mm, broadly obovate-spathulate, hairy outside, glabrous inside, not, or overlapping to c.½. Stamens at first clustered on the lower side of the mouth, becoming irregularly spreading, exserted to c.7mm; filaments linear, patently hairy for the lower ¼–1⁄3, glabrous distally; anthers 2–2.5 x c.1mm, broadly oblong, each cell with a small basal apiculus. Disc prominent, glabrous or with hairs on the upper margin. Ovary c.5 x 3mm, ovoid, densely patently white-hairy, and with scattered brown scales, abruptly contracted distally; style with a few hairs at the base otherwise glabrous, c.12mm, expanding to c.20mm, lying on the lower side of the tube; stigma rounded, bright red, becoming exserted to c.8mm. Fruit 12 x 6mm, obovoid-cylindric, dark purple, densely short-hairy and laxly scaly. Seeds 1.8mm, without tails 0.8mm, the longest tail 0.6mm.

Habitat: Terrestrial in summit shrubberies. Locally common.

Distribution: Malaysia (Borneo), Sabah, Mt Kinabalu, E ridge above the Mesilau R.

Altitude: 3160-3650m

Notes

Latin – Abies – genus of coniferous trees; folium – leaf. The distinctive narrow leaves superficially looking like those of an Abies.

This species has an extraordinarily restricted distribution, having been found only in the vicinity of the type locality.

Nomenclature

Type: Collenette 602, 12 Dec. 1960. North Borneo, Mt Kinabalu, new route (E ridge), c.3200m (L, K).

Flags

Occurs in Countries: MY Altitude Ranges: 3,000 - 4,000m Subgenus: Vireya Habit: Tree Fl. Colour: white

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:199

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Rhododendron acrophilum Merr. & Quisumb.

Shrub to 1m. Twigs 1–2mm in diameter, rounded, at first covered with flat stellate scales, quickly glabrescent; internodes 1.5–4cm. Leaves 4–6 in tight to somewhat loose pseudowhorls. Blade 25–50 x 10–20mm, elliptic or slightly obovate; apex broadly acute, obtuse to rounded; margin entire, flat, narrowly cartilaginous, often red; base broadly tapering; sub-densely scaly on both sides, glabrescent and shiny above, more persistently scaly below. Scales irregularly stellately lobed with a broad marginal flange and small slightly darker brown centre, not or only slightly impressed. Mid-vein slightly impressed into a narrow groove above, broad and slightly raised for the proximal 6–8mm beneath, otherwise smooth; lateral veins 6–8 per side curving upwards at c.45°, very slightly raised above, smooth or obscure beneath. Petiole 3–4 x 1.5–2mm, not or only weakly grooved above, flattened, scaly, and often minutely hairy. Flower buds to 27 x 12mm, ellipsoid or narrowly ovoid, acutely pointed, the tips of the bracts slightly spreading, white with conspicuous waxy deposits. Bracts to 15 x 8mm, ovate, apiculate, translucent, often flecked with brown, almost totally glabrous but with a few scales near the midline, lacking marginal scales. Inflorescence of 3–5 flowers in an open umbel, mostly horizontal but sometimes semi-erect to half-hanging, usually bicoloured with a yellow tube and orange lobes, sometimes pure yellow and occasionally almost completely orange. Pedicels 13–18 x c.1.5mm, red, sub-densely scaly, without hairs. Calyx obliquely thickened, disc-shaped, obscurely lobed, c.3mm in diameter. Corolla 15–30 x 40–55mm, shortly tubular-funnel-shaped; tube 10–15 x 6–7 x 12–17mm, sparsely stellately scaly outside, densely white-hairy inside; lobes 15–27 x 15–24mm, obovate, spreading horizontally or a little reflexed, overlapping to c.½ on upper side of the flower, not overlapping or only to 1⁄3 on the lower side. Stamens unequal, irregularly spreading, mostly on the lower side of the mouth, sometimes in two groups on each side, exserted to c.6mm but reflexing back against the corolla with age; filaments linear, white, densely white-hairy in the proximal 5–6mm, glabrous and filiform distally; anthers 2.7–3 x 1.25mm, narrowly oblong, shortly apiculate basally. Disc deeply lobed, minutely hairy on the upper side, otherwise glabrous. Ovary 5–6.5 x 2–3mm, cylindrical, abruptly contracted distally, densely stellate-scaly, without hairs; style 10–14mm, at first depressed to the lower side of the mouth, later becoming central in position, completely glabrous or with some scales at the base; stigma c.3mm in diameter, circular, yellow. Fruit 26–35 x 5–6mm, spindle-shaped, with pronounced longitudinal grooves, scaly.

Habitat: An epiphyte in dense montane rain forest.

Distribution: Philippines, Palawan, Mt Mantalinajan, Brooke’s Point.

Altitude: Around 1725m

Notes

Greek – acro – summit; philus – loving. A summit-loving plant but not apt – see below.

Known only from this single location.

Nomenclature

Type: Edaño PNH 34, 13 May 1947. Philippines, Palawan, Mt Mantalingahan, Brooke’s Point, at c.1725m (A, BM, K, L, PNH).

Flags

Occurs in Countries: PH Altitude Ranges: 1,000 - 2,000m Subgenus: Vireya Habit: Epiphyte, Non-Tree Fl. Colour: white

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:206

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Rhododendron acuminatum Hook.f.

Small shrub or shrub to 6m. Twigs short, spreading, rounded to obtusely angular especially towards the end of each internode; upper internodes 3–7cm, densely dark-scaly at the ends, silvery on older parts. Leaves 3–6 close together at the upper nodes or condensed in pseudo­whorls. Blade 60–120 x 25–60mm, ovate or elliptic-ovate; apex shortly-acuminate, obtuse; margin flat or slightly revolute; base mostly rounded, sometimes very broadly tapering, densely scaly on both sides initially, glabres­cent above, pits where the scales were attached remaining visible; beneath permanently covered. Scales overlapping with broad central cushions and wide irregularly lobed margins, the largest dark-brown, almost black, the smaller paler brown. Mid-vein strongly impressed above, thick and rigid beneath, continuing the petiole and gradually narrowing distally; lateral veins 6–8 per side, wide-spreading, from right angles to 45°, straight or slightly curved to the margin, distinctly anastomosing, deeply depressed above, strongly prominent beneath, veins laxly reticulate and distinctly impressed above, not or only slightly raised beneath, the whole surface deeply rugose; dark green and glossy above, brown beneath. Petiole 12–28 x 2–4mm, almost rounded in section, grooved above, densely scaly. Flower buds to 20 x 12mm, broadly ovoid, smooth. Bracts to 20 x 13mm, ovate, truncate at the base, obtuse at the apex, greenish but covered all over with minute, fine, brownish or greyish hairs and scaly outside along the median line and towards the apex outside, but glabrous towards the thin margin, the margin itself fringed with white hairs and occasional scales. Bracteoles to 15mm, linear to filiform, sub-spathulate-dilated at the top, patently hairy. Flowers 6–15 in an open umbel, hanging or half-hanging. Pedicels 8–12mm, thick, densely scaly and also finely hairy between the scales. Calyx c.2.5mm in diameter, a low scaly ring, or shallowly 5-lobed, densely scaly. Corolla 34 x 22mm, tubular or narrowly funnel-shaped, orange or red; tube 20 x 5–6 x 6–7mm, sub-densely to sparsely or occasionally glabrous outside, shortly sub-densely hairy in the lower ½ inside, straight, cylindrical, the base slightly 5-pouched; lobes 12 x 7–9mm, half-spreading, not overlapping, with a few well-spaced scales outside. Stamens arranged irregularly all round the flower, exserted to c.10mm, very slightly dimorphic; filaments linear, flattened nearly to the top, densely white-patent-hairy in the proximal 1⁄3; anthers 2.5–2.8 x 1mm, pale brown, without basal appendages. Disc glabrous. Ovary c.6 x 2mm, cylindrical, densely brown-scaly, gradually tapering to the thick style, which is scaly in its proximal ½ and lies on the lower side of the tube; stigma c.1.5mm in diameter, rounded, sometimes distinctly lobed. Fruit 25–34 x 4–5mm, cylindrical, longitudinally grooved, shortly tapering at both ends, densely scaly, splitting to the base, with the valves strongly curving back. Seeds 5–6mm, without tails 1mm, the longest tail 2.8mm.

Habitat: Terrestrial in mossy forest and open shrubberies, especially on ridges, occasionally as an epiphyte but always in well-illuminated situations. Occurring from 1830 to 3350m, common on Mt Kinabalu but subject to fluctuations in the size of the populations as it is a species which appears to be very adversely affected by droughts in El Niño years.

Distribution: Malaysia (Borneo), Sabah, Mt Kinabalu and one record from Mt Alab in the Crocker Range.

Altitude: 1830-3350m

Notes

Latin – acuminatus – tapering from inwardly curved sides to a narrow point, referring to the acuminate leaves.

The only natural hybrid recorded is with R. fallacinum, a solitary intermediate plant without flowers growing within the zone of overlap between these two species on Mt Kinabalu. It would be surprising if hybrids with R. lamrialianum did not also occur but these may be difficult to recognise without flowers. In cultivation this species appears difficult – most records of it growing successfully when checked have proved to be R. rugosum which although with superficially similar leaves has quite different dendroid scales. Of the many introductions to the Royal Botanic Garden Edinburgh just one has grown successfully, although very slowly. It flowered for the first time in 1997. Rhododendron acuminatum is quite distinct amongst section Malayovireya species. The orange to red, more or less hanging flowers are produced in a moderate-sized umbel, the leaves are long-petiolate and strongly rugose, the veins deeply impressed on the upper leaf surface and strongly protruding beneath. These vegetative characters are sufficient to separate this species from R. fallacinum which grows together with R. acuminatum in part of its range on Mt Kinabalu. The flowers of R. acuminatum are very sparsely covered (if not glabrous) with much smaller scales than R. fallacinum and the limp, slightly hanging disposition of the flowers in R. acuminatum is quite different. The flower buds are unusual in this section in often having occasional scales on the margins amongst the simple hairs. The variation in this character needs further observation.

Nomenclature

Type: Low s.n. Malaysia (Borneo), Sabah, Mt Kinabalu (K, CGE).

Flags

Occurs in Countries: MY Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Vireya Habit: Epiphyte, Non-Tree Fl. Colour: orange, red

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:111

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Rhododendron adenogynum Diels

Shrub or small tree, (0.5-)1.3-4m. Leaves narrowly elliptic to elliptic, 6-11 x 2-4cm, 2-2.5 x as long as broad, apex acute, base usually rounded, lower surface usually with a dense (rarely sparse) unistrate finely ramiform, spongy to matted tomentum, yellowish at first, maturing to a rich olive-brown, intermixed with at least some glands; petioles l-2cm, glabrescent or with a persistent tomentum and some stipitate glands. Inflorescence 4-12-flowered; rhachis up to 10mm; pedicels 20-30mm, densely tomentose and glandular. Calyx (4-)8-15mm, glandular, lobes oblong, unequal. Corolla campanulate, white flushed pink or pale pink, sometimes with purple flecks, 30-45mm. Ovary densely stipitate-glandular; style usually glandular in the lower third. Capsule 10-18 x 6-8mm.

Habitat: Thickets, open pastures, cliffs

Distribution: China (SE Xizang, W Yunnan, SW Sichuan)

Altitude: 3000-4250m

Illustrations:

Notes

The density of the glands on the leaves and petioles varies considerably; the most glandular forms have a leaf indumentum that has a matted appearance. There is however no justification for maintaining the essentially glandular R. adenophorum as distinct from the eglandular R. adenogynum as there is no clear dividing line between them.

8*. R. X detonsum Balfour f. & Forrest, Notes R.B.G. Edinb. 11: 48 (1919) - R. adenogynum x ? Type: China, Yunnan, Sungkwei divide, eastern flank, 10-11000ft, 26°12'N, v 1917, Forrest 13789 (holo. E; iso. K). Ic.: Bot. Mag. 157: t. 9359 (1934). Shrub, 1-3.5m. Leaves obovate to broadly elliptic, 6-10 x 3-4cm, 2.3-2.8 x as long as broad, apex acuminate, base rounded, lower surface with a sparse unistrate brown evanescent ramiform tomentum ; petioles 1.5-2cm, glabrescent. Inflorescence 6-10-flowered; pedicels 20-25mm, sparsely glandular. Calyx 3-5(-6)mm, glandular. Corolla campanulate, pink, with purple flecks, 40-50mm. Ovary glandular, also with a few hairs; style glandular for three-quarters of its length. Capsule unknown. china (W Yunnan). Rocky slopes, thickets, etc., 3050-3950m. There is every reason to believe that R. x detonsum is a natural hybrid of R. adenogynum, especially since a plant raised from seed of typical R. adenogynum (as Forrest 5868) is a good match with the type of R. x detonsum.

Nomenclature

Type: China, Yunnan, eastern flank of the Lichiang Range, 27°12'N, 11-12000ft, vi 1906, Forrest 2395 (holo. E; iso. K)

Synonymy: R. adenophorum Balfour f. & W. W. Smith, Notes R.B.G. Edinb. 9: 211 (1916). Type: China, Yunnan, mountains in the NE of the Yangtze Bend, 27°45'N, 12000ft, vii 1913, Forrest 10429 (holo. E; iso. A, K).

Flags

Occurs in Countries: CN Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Tree Fl. Colour: pink, purple, white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):340

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Rhododendron adenopodum Franchet

Shrub, up to 3m; young shoots densely tomentose, with a few stalked glands. Leaves coriaceous, obianceolate, 9-16 x 2.5-4cm, 2.6-4.5 x as long as broad, apex acuminate to shortly cuspidate, glabrous above when mature, with a dense, felted, grey to fawn indumentum beneath; petioles c.3cm, tomentose. Inflorescence lax, 6-8-flowered; rhachis 10-15mm; pedicels 30-40mm, long-stipitate-glandular. Calyx 3-6(-15)mm, lobes ligulate, membranous, gland-ular-ciliate. Corolla funnel-campanulate, pale rose, 42-50mm. Ovary densely fulvous long-stipitate-glandular; style glabrous. Capsule c.15 x 7mm, cylindrical.

Habitat: Thin woods

Distribution: China (E Sichuan, Hubei)

Altitude: 1500-2200m

Illustrations:

Notes

R. adenopodum has been traditionally included in subsection Pontica but differs from the remaining species in its stipitate-glandular ovaries and in its shallowly lobed corolla. Furthermore, its distribution is more in line with the other species in subsection Argyrophylla than it is with those of subsection Pontica.

Nomenclature

Type: E Sichuan, environs de Tchen-keou-tin, Farges (iso. E)

Synonymy: R. youngae Fang, Contr. biol. Lab. Sci. Soc. China, Bot. ser. 12: 24 (1939). Type: China, Sichuan, Nan-Chuan-hsien, Kin shan, 2000m, 13 iv 1930, Chang 59 (holo. SZ; iso. E, Hb. Inst. Bot. Guangzhou). R. simiarum Hance subsp. youngae (Fang) Chamberlain, Notes R.B.G. Edinb. 37:329(1979)

Flags

Occurs in Countries: CN Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: rose

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):318

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Rhododendron adenosum Davidian

Shrub; young shoots densely setose-glandular. Leaves ovate to lanceolate or elliptic, coriaceous, 7-10.5 x 2.4-3.4cm, c.3 x as long as broad, apex acute to acuminate, base rounded, margin cartilaginous, papillate, upper surface glabrous when mature, with a few setae overlying the midrib, lower surface setose and sparsely tomentose, tomentum evanescent, at least towards apex, or ± persistent; petioles, like midribs, densely glandular-setose. Inflorescence lax, 6—8-flowered; rhachis c.5mm; pedicels 15-25mm, densely glandular-setose. Calyx c.7mm, densely glandular-setose. Corolla (in cultivation) funnel-campanulate, pale pink with purple flecks, 35-50mm. Ovary densely glandular setose; style glabrous. Capsule c.20 x 4mm, curved. china (SW Sichuan-Muli). Spruce forests,

Altitude: 3350-3550m

Notes

Allied to R. glischrum and its immediate allies, but clearly differentiated by its leaf shape, texture and size. R. adenosum occurs in an area to the east of the range of R. glischrum. The wild-collected material lacks flowers; the details of the corolla have therefore been taken from cultivated specimens.

Nomenclature

Synonymy: R. glischrum var. adenosum Cowan & Davidian, Notes R.B.G. Edinb. 21: 147 (1953). Type: China, SW Sichuan, mountains of Kulu, 3540m, ix 1929, Rock 18228 (= Rock seed no. 3837, cult. E) (holo. E). R. kuluense Chamberlain, Notes R.B.G. Edinb. 36: 116 (1978)

Flags

Altitude Ranges: 3,000 - 4,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: pink, purple

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):284

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Rhododendron adinophyllum Merr.

Shrub to 1m. Twigs erect, rounded, 2–3mm in diameter, densely covered with low sub-circular scales, and sparsely very shortly hairy. Stems with prominent leaf scars and low rounded axillary protrusions. Leaves densely, spirally arranged. Blade 7–12 x 2–5mm, elliptic to narrowly elliptic, gradually acuminate; apex acute to obtuse; margin flat or slightly recurved sometimes slightly crenulate; base tapering, shiny dark green above, and gradually glabrescent, paler and sub-densely scaly beneath. Scales sessile, impressed, rounded, with the margin narrow, entire to undulate; centre large and dark brown. Mid-vein impressed above and obtusely raised beneath especially in the proximal ½, lateral veins obscure. Petiole 1–2.5 x c.1mm, grooved, laxly scaly and hairy above, densely scaly below, curved to a right angle with the blade. Flower buds 10–12 x 7–10mm, ovate, smooth with the bracts fully appressed, brown near the base and the tips of the bracts, otherwise green. Bracts to 7 x 4mm, gradual changing from the upper foliage leaves, ovate to obovate, apiculate, scaly in the distal ½ and with short appressed hairs outside throughout; fringed with long white hairs at the margins. Bracteoles to 6mm, filiform, hairy. Inflorescence 6–12-flowered, the flowers half-hanging to hanging. Pedicels 10–14 x c.1mm, pink, densely covered with patent hairs of various lengths and sparsely scaly. Calyx oblique, small, undulate, with white hairs and scales outside and at the margin, glabrous inside. Corolla 18–21 x 8–9mm, tubular, bright orange-red, without scent; tube 13–15 x 5–6 x 7–8mm, with long white patent hairs and small laxly spaced scales outside, glabrous inside; lobes 3–5 x c.4mm, straight not reflexed, overlapping up to c.¾, obovate, apex rounded, hairy and scaly along the midline to the apex. Stamens exserted to c.2mm, loosely clustered on the lower side of the mouth, unequal; filaments linear, glabrous; anthers oblong-ellipsoid, c.1.5mm. Disc glabrous. Ovary c.3 x 2mm, ovoid-conical, densely covered with overlapping scales, without hairs; style glabrous, green; stigma elongate-obconical. Fruit c.11 x 4–6mm, elongate-ovoid, densely scaly, 5-ribbed, with a c.10mm persistent style; valves half-spreading, slightly curved, not twisted, the placentae remaining firmly attached to the central column. Seeds 1.3–1.8mm, without tails c.1mm, the longest tail to 0.5mm. The very short tails are often highly branched.

Distribution: Indonesia, N Sumatra, Atjeh, Gajolands: Mt Losir, Mt Lembuh, Mt Putjuk Angasan and Mt Kemiri. In open summit heathland

Altitude: 2600-3460m

Notes

Greek – adinos – close; phullon – leaf. Alluding to the densely leafy stems.

A wild hybrid of this species with R. sumatranum was collected by David Binney on Mt Kemiri, Sumatra (19982482) in 1998.

Nomenclature

Type: Ripley & Ulmer 58. Indonesia, Sumatra, Atjeh, Mt Losir (PH, A).

Flags

Occurs in Countries: ID Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Vireya Habit: Non-Tree Fl. Colour: orange, white

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:42

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Rhododendron aequabile J.J.Sm.

Large shrub or tree to 4m. Twigs thick, rounded, densely dark-brown scaly; internodes 3.5–16cm. Leaves 6–9 together in tight pseudowhorls at the upper 2 or 3 nodes. Blade 40–90 x 20–40mm, elliptic; apex shortly acuminate or apiculate, sub-acute to obtuse; margin broadly revolute (the leaves somewhat convex); base tapering, glabrescent at maturity above, or with a few small silvery scales remaining, very densely dark-brown persistently scaly beneath. Scales entire, with a broad marginal flange and moderately large, dark centre, dense with many touching or slightly overlapping. Mid-vein impressed over its entire length above, strongly prominent beneath; lateral veins 5–10 per side, spreading, straight below, anastomosing towards the edge, slightly but distinctly depressed above, weakly raised beneath or indistinct. Petiole 18–22 x 2–3mm, distinctly grooved above in the distal ½, densely brown-scaly. Flower buds spherical, brown, but with long, wide-spreading, protruding, broadly subulate bract apices, and a long acute point. Bracts broadly ovate, long acuminate, densely brown-scaly in the upper ½ outside, green near the base, inside brown-scaly for a broad band near the margins and densely scaly on the acumen. Bracteoles to 10mm, filiform, with just a few scales. Inflorescence of 5–10 flowers held horizontally in a compact, open umbel. Flowers 15–18 x 34–40mm, orange, without scent. Pedicels 10–14 x 2–3mm, orange, thickened distally, often curved, densely scaly with some long stalked scales but without hairs. Calyx 3–4mm in diameter, small, oblique, disc-shaped, angular, densely scaly outside. Corolla campanulate; tube 11–15 x 7–10 x 16–20mm, laxly to sub-densely inconspicuously scaly outside, glabrous inside; lobes 12–15 x 17–21mm, obovate-circular, rounded, slightly retuse, or sometimes subdivided into miniature lobe-like structures, spreading horizontally or reflexed back, with some scales outside near the base, overlapping to c.halfway. Stamens regularly arranged all round the mouth of the flower, very slightly dimorphic; filaments 10–13mm, pink, linear, glabrous; anthers c.2 x 1mm, oblong, dark brown, exserted to c.2mm. Disc glabrous. Ovary c.4 x 3.5mm, conical-ovoid, densely scaly, without hairs, abruptly contracted distally; style 8–10mm, glabrous; stigma 2–3mm in diameter, centrally placed in the mouth, rounded to weakly 5-lobed. Fruit ellipsoidal, 14–17 x 6–7mm, smooth, densely brown-scaly. Seeds 4mm including the tails.

Habitat: In dense sub-alpine forest

Distribution: Indonesia, Sumatra, West Coast to Benkulen: Mt Singgalang, Mt Kerintji, W side of Barisan Range and Mt Pesagi.

Altitude: 2300-2870m

Notes

Latin – aequabilis – uniform or consistent; a rather obscure reference.

First introduced into cultivation by Dr Willem Meijer who collected seed from the type locality which was distributed by the Rijksherbarium in 1957 and grown successfully at Kew, where it was figured in Curtis’s Botanical Magazine (Hunt 1974). It was also collected by Peter Valder in 1975 (see History chapter); progeny from his plants are now widely cultivated. This species is one of the easiest of the albovireyas and has most attractive deep bronze new foliage. The bright orange flowers can be disappointing when the plants are young, often being overtopped by new foliage, but as the plant matures the flowers become more prominent and often give a wonderful display of colour. Flowering appears to be irregular in cultivation, often with two good flowerings a year and sometimes the occasional odd branch flowering out of synchrony with the rest of the plant.

Nomenclature

Type: Docters van Leeuwen 3985, 29 Jan. 1920. Sumatra, Mt Singgalang (BO, A, L, SING).

Synonymy: R. album (non Blume) Ridl., J. Fed. Mal. St. Mus. 1917. 8: 58.

Flags

Occurs in Countries: ID Altitude Ranges: 2,000 - 3,000m Subgenus: Vireya Habit: Tree

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:129

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Rhododendron afghanicum Aitchison & Hemsley

Low shrub to 0.5 m. Young growth lepidote and sometimes puberulent. Leaves narrowly elliptic to elliptic, 47-80 x 13-25 mm, thick, apex ± obtuse, base rounded-cuneate, lower surface pale green, scales 1-2 x their own diameter apart, upper surface dark green, elepidote, puberulent along the main vein at the base (and along the petiole). Inflorescence rachis 20-50 mm, flowers 12-16, pedicels densely lepidote. Calyx lobes variable in shape, from narrowly triangular to oblong, apex acute or rounded, 4-6 mm, lepidote, often margined with scales. Corolla white or greenish white, with tubular base and rotate limb, tube 6-8 mm, lobes c. 5 mm, elepidote and glabrous outside, sparsely pilose within the tube. Stamens 10, exserted, filaments pilose towards the base. Capsule lepidote, ± cylindric, c. 7 mm

Habitat: Cliffs and forests

Distribution: Afghanistan, Pakistan

Altitude: 2000-3000m

Illustrations:

Notes

Known from several collections from the Kurrum valley, which crosses the border between Afghanistan and Pakistan

Nomenclature

Type: Afghanistan, Kurrum valley, abundant from 7-8000 ft, at Shendtoi Kaiwas, Aitchison (holo. K)

Flags

Occurs in Countries: AF, PK Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: green, white

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):156

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Rhododendron aganniphum Balfour f. & Kingdon-Ward

Shrub, 0.3-3m. Leaves elliptic to broadly ovate-lanceolate, 4-12 x 2-5cm, 1.7-2.5(-2.8) x as long as broad, apex ± acute, base cuneate to rounded-cordate, lower surface covered with a dense unistrate compacted to spongy ramiform tomentum, whitish or yellowish at first, sometimes turning deep reddish-brown, continuous, or splitting and becoming patchy; petioles l-2cm, tomentose at first, later glabrescent. Inflorescence 10-20-flowered; rhachis less than 5mm; pedicels 10-30mm, sparsely tomentose to glabrescent. Calyx 0.5-lmm, glabrous Or with a few scattered glands, lobes rounded. Corolla campanulate, white, often flushed with pink, with purple flecks, 30-35mm. Ovary and style glabrous. Capsule 10-20 x 4-6mm.

Habitat: Open forests, among rocks

Distribution: China (SE Xizang, NW Yunnan, SW Sichuan)

Altitude: 3350-4550m

Notes

R. aganniphum was originally distinguished from R. glaucopeplum by its supposedly eglandular leaf indumentum. The type of the former does however have a few glands; R. glaucopeplum is therefore reduced to synonymy.

Five specimens from S Xizang, an area to the W of the main range of the species, are atypical in their stiff broad leaves (resembling R. clementinae) but the corollas are 5-lobed. The status of these plants-Ludlow, Sherriff & Elliot 12002; Ludlow & Sherriff 811, 1568, 1760; and Kingdon-Ward 11613-s uncertain.

R. aganniphum apparently intergrades with R. phaeochrysum, at least locally (q.v.).

Flags

Occurs in Countries: CN Altitude Ranges: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: pink, purple, white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):354

Rhododendron aganniphum var. aganniphum

Indumentum remaining pale and intact at maturity

Nomenclature

Type: China, Yunnan/Xizang Border, Dokar La, 14-15000ft, Kingdon-Ward'768 (iso. E).

Synonymy: R. schizopeplum Balfour f.& Forrest, Notes R.B.G. Edinb. 11:13(1919). Type: China, NE Yunnan, mountains NW of Atuntze, 28°35'N, 14000ft, vi 1917, Forrest 14094 (holo. E). R.fissotectum Balfour f. & Forrest, ibid. 13:44 (1920). Type: China, NW Yunnan, W of Atuntzi, vi 1917, Forrest 14049 (holo. E; iso. K). R. glaucopeplum Balfour f. & Forrest, ibid. 13: 46 (1920). Type: China, NW Yunnan, Mekong/Yangtze divide, vii 1917, Forrest 14133 (holo. E; iso. K). R. doshongenseTagg, Notes R.B.G. Edinb. 15: 310 (1928). Type: China, Xizang, Doshong-La, 12-13000ft, 26 vi 1924, Kingdon-Ward 5863 (holo. E; iso. K).

Rhododendron aganniphum var. flavorufum (Balfour f. & Forrest) Chamberlain

Indumentum turning deep red-brown and becoming patchy

Notes

Var. flavorufum intergrades with var. aganniphum and there are a number of intermediates that could be referred to either variety. Extreme forms are however clearly distinct.

Nomenclature

Synonymy: R. flavorufum Balfour f. &Forrest, Notes R.B.G. Edinb. 11: 65 (1919). Type: China, SE Xizang, Tsarong, on Ka-gwr-pw, Mekong/Yangtze divide, 28°10'N, 14000ft, vii 1917, Forrest 14345 (holo. E; iso. K).

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Rhododendron agastum Balfour f. & W. W. Smith

Shrub, 1.5—3m. Leaves coriaceous, obovate to elliptic, 6-11 x 2.5-5cm, 2.2-2.5 x as long as broad, apex rounded, acuminate, base rounded, margin not undulate, upper surface glabrous, lower surface with a thin veil of dendroid hairs embedded in a surface film, with numerous red punctate hair-bases overlying the veins; petioles 1.5—2cm, glabrous. Inflorescence 10-15-flowered; rhachis at most 5mm; pedicels 15—20mm, stipitate-glandular. Calyx 2—3mm, lobes rounded, glandular. Corolla campanulate to tubular-campanulate, with nectar pouches, glabrous within, rose-pink, usually with darker margins and at least a few crimson flecks, 40—50mm. Ovary stipitate-glandular, with a few rufous dendroid hairs; style glandular, usually almost to tip. Capsule up to c.30 X 9mm, curved.

Habitat: Rhododendron thickets, open pine forests, stony slopes

Distribution: China(W Yunnan)

Altitude: 2200-3350m

Notes

Closely allied to R. leptopeplum and R. tanastylum but distinguished from both by the glandular style and the leaf shape. Two gatherings, McLaren L 49 & L 60, may be hybrids of this species. The leaf indumentum suggests R. agastum but the more acute leaves and almost glabrous styles do not.

Nomenclature

Type: China, W Yunnan, head of the Taping-pu Valley, 7000-8000ft, v 1913, Forrest 9920 (nolo. E).

Flags

Occurs in Countries: CN Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: crimson, rose

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):301

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Rhododendron agathodaemonis J.J.Sm.

Shrub or small compact tree to 6m. Twigs rounded, tips laxly to densely reddish-brown, scaly. Leaves 4–5 together in pseudowhorls, spaced 7–20cm apart. Blade 40–75 x 25–48mm, elliptic to obovate-elliptic; apex broadly acuminate to obtuse, sometimes apiculate by a small gland or a little retuse; margin entire, somewhat revolute proximally; base broadly tapering to the petiole or rounded-obtuse, sparsely to sub-densely minutely scaly on both sides especially beneath. Scales circular, entire or shallowly undulate at the marginal zone; centre large, impressed. Mid-vein slightly impressed above, distinctly raised though somewhat flattened beneath; lateral veins 6–10 per side, straight, anastomosing with each other and the primary veins near the edge, very slightly impressed above, a little raised or inconspicuous beneath, reticulation obscure, rarely distinct. Petiole 9–22 x 1.5–2mm, grooved above, somewhat flattened and sparsely scaly. Bracts c.15 x 10mm, ovate to obovate, scaly outside. Bracteoles c.12 x 1mm, filiform below, linear-spathulate distally, sparsely scaly. Inflorescence an open umbel of 6–12 flowers. Pedicels 6–18mm, thick, densely scaly. Calyx very small, circular, irregularly denticulate. Flowers trumpet-shaped but broadest just above the middle, white or with the tube tinged with pink, with the scent of carnations. Corolla 80–100 x 15–20mm; tube 70–85 x 3 x 4–6.5mm, cylindrical at least below, curved, sparsely to sub-densely scaly outside, laxly hairy and often sparingly scaly, in the lower ½ inside; lobes 10–15 x 8–12mm, rounded to obovate, spreading at a right angle, sparsely scaly or mostly glabrous outside, glabrous inside. Stamens slightly or not exserted from the throat; filaments very slender, sub-densely to sparsely covered with spreading hairs in the lower ½, glabrous above; anthers 3–4 x 0.8mm, orange, oblong, the cells apiculate at the base. Disc glabrous. Ovary 7–10 x c.2mm, elongate-conical, densely scaly; style slender, slightly exserted, densely to laxly scaly almost to the top, without hairs; stigma shortly conical, crenulate. Fruit c.100 x 5–6mm, red-brown, cylindrical, tapering at both ends, obtusely 5-angled.

Habitat: Moss forest, in damp ground or swampy open places

Distribution: Indonesia, New Guinea (W), Mt Agathodaemontop in Hellwig Mts; Mts Hubrecht and Wichmann on the southern and near Lake Habbema on the northern side of the Orange Mts; Mt Amdutakin in the Hindenberg Range. Papua New Guinea, Telefomin, West Sepik District and W of Oksapmin.

Altitude: 2500-3450m

Notes

Named after the mountain from which it was first collected which in turn was named after the Greek god Agathodaimon, the good genius, to whom a cup of pure wine was drunk at the end of dinner.

An odd form was collected by Katik & Taho (NGF 37952) from Tukwabit village, Lae, Morobe District. This is much further east than all the other collections and from considerably lower altitude (1800m). It had remarkably short broad flowers c.60mm long and with a broad tube up to 10mm wide. The bracts were shortly hairy outside and this specimen would appear to be intermediate between this species and R. herzogii or possibly a hybrid. The differences between R. agathodaemonis and R. herzogii are not clearly established. Sleumer (1973) modified his view of the difference from his (1966) Flora Malesiana account in the light of observations on flower length made by Peter Stevens and then made the chief difference fruit size. On the basis of limited herbarium specimens especially of R. agathodaemonis there does seem to be a difference in the corolla tube shape which is used in this account, and bract shape may produce further good morphological differences. Further observations are needed to clarify the situation.

Nomenclature

Type: von Römer 1245. Mt Agathodaemontop, Hellwig Mts, Papua New Guinea, 2577m (BO).

Flags

Occurs in Countries: ID, PG Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Vireya Habit: Tree

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:63

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Rhododendron alabamense Rehder

Shrub or small tree to 3(-5)m tall, usually non-rhlzomatous; young twigs red- or yellow-brown, sparsely to densely covered with unicellular and multicellular eglandular hairs, occasionally only multicellular eglandular hairs present, rarely with both unicellular and multicellular gland-tipped hairs. Vegetative bud scales glabrous to sparsely unicellular pubescent abaxially; margin unicel-lular-ciliate, rarely ciliate and glandular. Leaf blade membranaceous, ovate or obovate to elliptic, 6.1-7.7(-9.4) x 1.9-2.3(-2.4)cm; base acute to oblique; apex acute to obtuse, often mucronate; adaxial surface sparsely to densely covered with unicellular and multicellular eglandular hairs, the young unfolding leaves rarely with multicellular gland-tipped hairs, occasionally glabrous to sparsely covered with only unicellular hairs, rarely only with scattered multicellular eglandular hairs, the midvein sparsely to densely covered with unicellular hairs; abaxial surface sparsely to densely covered with unicellular hairs, rarely glabrous, the midvein and secondary veins densely covered with unicellular and multicellular eglandular hairs, rarely with multicellular gland-tipped hairs; margin entire, ciliate with multicellular eglandular hairs; petiole 0.2-0.5(-0.8)cm long. Flower bud scales chestnut brown; abaxial surface glabrous to very sparsely covered with unicellular hairs; margin unicellular ciliate. Flowers appearing before or as the leaves expand; inflorescence a shortened raceme of 6 to 12 flowers. Pedicels (0.4-)0.6-0.9(-l ,2)cm long; usually sparsely to densely covered with unicellular, multicellular eglandular and gland-tipped hairs, but occasionally lacking unicellular or multicellular gland-tipped hairs. Sepals less than 0.1-0.2 (-l.O)mm long, often varying in length on the same flower; margins setose with multicellular eglandular hairs, rarely glandular-fimbriate; abaxial surface sparsely to densely covered with unicellular and multicellular eglandular hairs, occasionally only with unicellular hairs, or with unicellular and multicellular gland-tipped hairs, or with unicellular, multicellular eglandular and gland-tipped hairs. Corolla white with a yellow blotch on the upper corolla lobe, fragrance sweet and delicate, the tube longer than the limb and gradually expanding into it; upper corolla lobe 0.9-1.4(-1.5)x(0.7-)0.8-1.2(-1.3)cm;laterallobes(1.0-)l.l-1.7(-1.9)x(0.5-)0.6-1.0(-1.2)cm corolla tube (1.6-)1.7-2.4(-2.8) x 0.1-0.3(-0.4)cm wide at base; outer surface of corolla sparsely to densely covered with unicellular and multicellular gland-tipped hairs, the gland-tipped hairs often continuing In tines up the corolla lobes; Inner surface of corolla densely covered with unicellular hairs. Stamens (3.7-)4.5-6.1(-6.6)cm long, with dense terete or flattened unicellular hairs on proximal 2.3-3,4(-3.8)cm of filament, exserted (1.7-)2.5-3.9(-4.5)cm beyond throat of corolla. Style (3.5-)4.4-6.4(-7.4)cm long, with dense unicelluar hairs on proximal (0.0-)0.4-1.3(-1.7)cm, exserted (1.7-)2.7-4.3(-5.2)cm beyond throat of corolla, stigma (0.15-)0.12-0.2 (-0.3)cm wide. Ovary 0.2-0.4cm long, 0.1-0.2cm wide at the base, densely covered with multicellular eglandular hairs over unicellular hairs, rarely with multicellular gland-tipped hairs or with both eglandular and gland-tipped hairs. Capsules (1.4-)1.5-2.1(-2.2) x 0.3-0.4cm, narrowly ovate to cylindiic, moderately to densely covered with unicellular hairs and sparsely to moderately covered with multicellular eglandular hairs. Seeds pale to dark chestnut brown, ovate or elliptic to fusiform, (1.8-)2.1-3.2(-3.8) x 0.4-0.8(-1.0)mm, body (0.9-)l.l-1.8(-1.9) x 0.2-0.5mm; testa expanded and dorsiventrally flattened surrounding the body, the cells elongate, with tapering end-walls

Habitat: Upland woods, bluffs and hillsides along water-courses, stream bottoms

Distribution: USA: Alabama and adjacent Tennessee, Georgia and Florida.

Altitude: 0-500m

Illustrations:

Notes

Hybrids between R. alabamense and R. canescens are known to occur in Harris Co., Early Co. and Clarke Co., Georgia; Tishomingo Co., Mississippi; and Leon Co., Florida. These plants generally possess glabrous bud scales, and pink corollas with a yellow blotch on the upper corolla lobe. See Appendix for citation of representative specimens of these hybrids.

The variation in flower colour from all white to tinged with pink has been suggested to be a result of hybridization and subsequent introgression with R. canescens (Skinner, 1955,1961). In addition, the slightly pubescent bud scales of some individuals have also been considered as evidence of widespread hybridization (Skinner, 1961). While hybrids between R. alabamense mdR. canescens do occur (see below), pink-tinged corollas also occur in otherwise all white populations of R. viscosum, R. atlanticum and R. arboresc ens. Therefore the pink blush on an otherwise white corolla does not necessarily imply the historical occurrence of hybridization with a pink-flowered species. Likewise, the variation in pubescence on the floral bud scales does not always require the occurrence of hybridization with R. canescens. Pubescent bud scales are found scattered throughout the range ofR. alabamense and do not seem to be more common in the southern part of this species'range as suggested by Skinner (1961).

This species is more common in north-central Alabama, especially in Winston, Cullman and Tuscaloosa counties, than in other parts of its range where it has arather discontinuous distribution. The yellow blotch on the upper corolla lobe distinguishes R. alabamense from the other white-flowered species in eastern North America. It is isolated from the sympatric R. viscosum and R. arbor esc ens by flowering time. Without flower colour R. alabamense is often difficult to distinguish from R. canescens. In general R. alabamense has much less unicellular pubescent corollas and the floral bud scales are glabrous or only slightly unicellular pubescent. In addition, these two species are often ecologically isolated as R. alabamense occurs in dry woods and R. canescens usually occurs in bottom-lands and along stream banks.

Chromosome number: 2n = 26 (Janaki-Ammal et al., 1950; Li, 1957)

Flowering primarily in April and May, but occasionally as early as March or as late as June.

Nomenclature

Synonymy: Azalea alabamense (Rehder) Small, Man. S.E. US Fl. 996 (1933). Type: Alabama, Cullman Co.: without definite locality, T. G. Harbison 6292 (holo. US).

Flags

Occurs in Countries: US Altitude Ranges: 0 - 1,000m Subgenus: Pentanthera Habit: Tree Fl. Colour: yellow

Kron, K.A. (1993) A Revision of Rhododendron Section Pentanthera. Edinburgh Journal of Botany 50(3):284

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Rhododendron albertsenianum Forrest

Shrub, l-2m; young shoots floccose-tomentose, eglandular. Leaves elliptic, 8.5-9.5 X c.2.2cm, c.4 x as long as broad, apex rounded, apiculate, base rounded, upper surface glabrous, lower surface with a continuous bistrate indumentum, the upper layer light brown and ramiform-tomentose, the lower layer felted and ± compacted; petioles 0.5-lcm, sparsely floccose-tomentose. Inflorescence 5-6-flowered; rhachis 2-3mm; pedicels c.lOmm, sparsely tomentose. Calyx cupular, 3-4mm, lobes fleshy, sparsely tomentose, rounded. Corolla tubular-campanulate, bright crimson-rose, c.30mm. Ovary densely tomentose, tapering into the style. Capsule not known.

Habitat: Open forests

Distribution: China (NW Yunnan)

Altitude: Around 3000m

Notes

Only known from the type specimen which is apparently part of a mixed gathering which includes elements that have affinities with R. sperabile. R. albertsenianum and the next species, R. euchroum, share a bistrate indumentum, a rare feature in subsection Neriiflora.

Nomenclature

Type: China, W NW Yunnan, Mekong/Salween divide, 27°40'N, 10000ft, vii 1917, Forrest 14195 (holo. E)

Flags

Occurs in Countries: CN Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: crimson

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):413

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Rhododendron albiflorum W. J. Hooker

Deciduous shrub to c.2 m high, young branches with brown strigose hairs. Leaves scattered along the shoots or clustered at their ends; blade membranous, narrowly elliptic or lanceolate to oblanceolate, to c.80 x 24 mm, base narrowly cuneate, apex acute, margin minutely serrate, when young ciliate on the mid-rib and margin, becoming more or less glabrous; petiole c.4 mm long, with strigose hairs. Inflorescence buds lateral, spaced along the shoots of the previous year, above leaf scars, 1-2-flowcred, flowers pendulous, borne below the expanded leaves; bud scales mostly fallen at anthesis; pedicels up to c. 10 mm long, with a minute glandular indumentum, and strigose hairs around the base. Calyx lobes oblong-ligulate, deeply divided, c.8 x 3-4 mm, with glandular hairs on the margin and strigose and glandular hairs on the outer surface. Corolla bowl-shaped, almost actino-morphic, c.20 mm across, with a short tube and spreading lobes, white (rarely marked with yellow), usually minutely puberulous on the inner and outer surfaces. Stamens 10(12 in rare6-merous flowers) equal, filaments c.lOmm long, pilose below. Ovary globose, 2 mm long, setose and glandular; style straight, impressed, pilose below. Capsule globose, enclosed in the persistent calyx, c.8 mm long, glandular and with strigose hairs. Seed with ligulate appendages at each end.

Habitat: Undershrub in upper montane forest and forming thickets in open places at and above the tree line and along stream banks

Altitude: 1200-2300m

Notes

An erect growing shrub often with trailing branches from the base of the plant. The white nodding cup-shaped flowers scattered along the leafy branches are distinctive, and resemble a prunus rather than a rhododendron. The flowers are borne on short lateral leafy branches along the main stems and also below the terminal cluster of leaves.

Nomenclature

Type: USA, Rocky Mts, Drummond s.n. (holo. K).

Synonymy: Cladothamnus campanulatusGreene,Erythraea3:65(1895). Described from Canada (British Columbia) and the USA (Washington State). Azaleastrum albiflorum (Hooker) Rydberg, Mem. New York Bot. Gard. 1:297 (1900). A. warreniiA. Nelson, Bot. Gaz. 56:67 (1913). Type: USA, Colorado, Jackson Co., Mt Zarkel, 14 vii 1911, Warren. R. warrenii(A. Nelson) Macbridc, Contr. Gray Herb n.s. 56:55(1918). Ic: Bot. Mag. 65, t 3670(1839).

Flags

Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Candidastrum Habit: Non-Tree

Philipson, W.R. & Philipson, M.N. (1986) A Revision of Rhododendron III. Subgenera Azaleastrum, Mumeazalea, Candidastrum and Therorhodion. Notes from the Royal Botanic Garden Edinburgh 44(1):17

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Rhododendron alborugosum Argent & J.Dransf.

Shrub to 3m. Twigs smooth, finely longitudinally striated when dry and with scattered dark-brown scales; internodes 5–12cm. Leaves 3–5 together in tight pseudow­horls. Blade 40–80 x 23–37mm, elliptic, narrowly ovate or obovate; apex broadly acute, obtuse or rounded; margin entire, slightly revolute; base broadly tapering to rounded; laxly silvery scaly but quickly glabrescent and dark green above, persistently laxly scaly and paler below. Scales rounded, variable in size, with a broad marginal flange and small centre. Mid-vein distinct, above broad at the base and longitudinally grooved but quickly tapering to a narrow, impressed channel, green; broad and strongly raised throughout its length below, deep reddish-purple; lateral veins 7–9 per side, issuing at an angle of 45–90°, strongly impressed above, almost to the leaf edge, giving a rugose surface, very prominent and red in colour below. Petiole 8–12 x 3–4mm, red, weakly grooved above, scaly. Flower buds to c.20 x 10mm, glossy dark purplish-red, elliptic. Bracts ovate, often with a dark purple median line, the tips of the bracts broadly pointed and reflexed to c.4mm, these tips scaly both inside and out. Inflorescence a 6–10-flowered open or one-sided umbel, the flowers semi-erect to horizontal, white, or pale pink, fragrant. Pedicels red, 12–26 x c.2mm, minutely rough with scales and short simple hairs. Calyx a low lobed scaly and hairy ring, 1–1.5mm high. Corolla 40–46 x 35–45mm; tube 35–40 x 9 x 5mm, straight, covered in scales outside, densely short-hairy inside near the base; lobes 18 x 14–18mm, slightly forward pointing or spreading to the perpendicular, overlapping to c.halfway, slightly scaly outside. Stamens irregular in length, included c.2mm below the mouth; filaments white or pale pink, tapering slightly distally, hairy throughout their length; anthers c.2.8 x 1.25mm, brown with a finely granular surface and oblique pores. Disc lobed, with short erect hairs. Ovary 5.5 x 3.5mm, ovoid to almost conical, tapering slightly towards both base and apex, densely scaly and covered in short forwardly directed hairs; style 37 x c.1mm, sparsely scaly in the lower 1⁄3 and with forwardly directed, semi-patent hairs to within 3–4mm of the stigma; stigma irregularly lobed, c.1mm, cream, eventually protruding to 6mm from the mouth of the flower. Fruit 17–25 x 4–7mm, narrowly ellipsoid, strongly longitudinally grooved. Seeds 4–4.5mm, without tails c.1.1mm, the longest tail to 1.9mm.

Habitat: It grows in upper montane, mossy forest dominated by Phyllocladus, Drimys and Vaccinium and is common in open islands of scrub amongst bryophytes and lichens on the summit sandstone ridge.

Distribution: Indonesia, S Kalimantan (Borneo), Pergunungan, Meratus, Mt Halauhalau (G. Besar).

Altitude: 1400-1800m

Notes

Latin – albo – white; rugosum – the name of another superficially similar Bornean Rhododendron species but differing in the white (or very pale) flower colour.

It is known only from the mountain on which it was originally collected.

Rhododendron alborugosum is a very distinct species. It was originally confused with R. rugosum no doubt because of a superficial resemblance in the rugose leaves, but that species has dendroid scales, and pendent, much darker pink flowers. It has also been determined in the past as R. suaveolens Sleumer, which has superficially similar flowers, but that species has smooth, much larger leaves, a corolla which is glabrous outside and a much larger umbel of 14–20 flowers.

Nomenclature

Type: Dransfield 2910, 24 Oct. 1972. Indonesia (Borneo), South Kalimantan, Mt Halauhalau (G. Besar), Pergunungan, Meratus, Barabai (BO, L).

Flags

Occurs in Countries: ID Altitude Ranges: 1,000 - 2,000m Subgenus: Vireya Habit: Non-Tree

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:162

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Rhododendron albrechtii Maxim.

Shrub to 2.5m tall; bark thin with shallow vertical furrows; young twigs pale to reddish brown, sparsely to moderately covered with multicellular gland-headed hairs, becoming glabrous with age; new foliage shoots arising from axillary buds associated with foliage leaves of the previous year's shoot (i.e. below terminal bud), and some terminal buds. Vegetative bud scales glabrous to moderately unicellular-pubescent abaxially, sometimes with a few multicellular gland-headed hairs near apex, sparsely to moderately unicellular-pubescent adaxially, especially near apex, and sometimes with a few multicellular gland-headed hairs near apex; margin fringed with unicellular hairs or with mixed unicellular and gland-headed hairs; lowermost scales with long aristate apices or rudimentary blades. Leaves deciduous, dark green adaxially, pale green or occasionally glaucous abaxially, turning yellow to red in autumn, alternate (with internodes becoming more closely spaced towards tip of shoot), thus leaves sometimes appearing pseudowhorled at shoot apices. Blade membranaceous, obovate to occasionally elliptic, 2.1-13.5 x0.9-6.3cm; base attenuate with blade decurrent along petiole; apex shortly acuminate, acute to obtuse, with a short mucro; midvein strongly raised and prominent abaxially, the secondary veins slightly raised abaxially; adaxial surface, including midvein, moderately covered with multicellular gland-headed and eglandular hairs, the midvein unicellular-pubescent; abaxial surface glabrous to moderately covered with unicellular hairs, especially near base, and usually with a few multicellular gland-headed hairs, the lateral (and sometimes all) surfaces of midvein very sparsely to densely covered with straight to crisped, unicellular hairs, especially towards base, and with multicellular gland-headed hairs and usually also + flattened glandular to eglandular hairs, the secondary and tertiary veins similar but less frequently unicellular-pubescent and usually lacking!flattened glandular hairs; margin serrulate and often with conspicuous irregular undulations, with a fringe of multicellular gland-headed and eglandular hairs; petiole ± lacking to 6mm long, sparsely unicellular-pubescent, especially adaxially, and with scattered multicellular gland-headed hairs, the base of petiole abruptly expanded into a very broadened point of attachment, forming a ± triangular'slight protuberance below terete portion. Flower buds larger than, but otherwise similar to, vegetative buds. Flowers appearing before or with the leaves; inflorescence an umbellate raceme of 2 to 5 flowers. Pedicels 5-27mm long, moderately to densely covered with multicellular gland-headed hairs, sometimes also sparsely unicellular-pubescent. Calyx lobes broadly Ungulate to ovate-triangular, 1-3.5 x 1.5-2mm; apex rounded; margin fringed with multicellular gland-headed and sometimes also eglandular hairs; adaxial surface glabrous; abaxial surface sparsely to densely covered with multicellular gland-headed hairs, sometimes also very sparsely unicellular-pubescent. Corolla pink to red-purple, with greenish spots on the upper 3 lobes, fragrant, zygomorphic, broadly rotate to funnelform, the tube much shorter than the limb and gradually expanding into it; upper corolla lobe 1-1.7 x 1-1.6cm; laterallobes 1.2-2.2x0.7-1.7cm; corolla tube 0.4-lcm long; outer surface of corolla glabrous; inner surface of corolla sparsely unicellular-pubescent towards base. Stamens 10, declinate, dimorphic, the upper 5, 0.8-1.7cm long, the lower 5, 2.2-3.3cm long, included to equalling corolla; filaments glabrous distally, becoming densely covered with flattened unicellular hairs proxi-mally, the shorter filaments more pubescent than the longer ones. Ovary 3-4mm long, moderately to densely covered with multicellular gland-headed hairs, sometimes with a few unicellular hairs at apex; style declinate, 2.4-3.4cm long, glabrous to unicellular-pubescent near base. Capsules ovoid, 0.8-1.3 x 0.5-0.7cm, moderately covered with multicellular gland-headed hairs, sometimes with a few unicellular hairs at apex. Seeds shiny and light brown, ellipsoid, 0.7-1.6x0.3-0.5mm; testa tightly appressed to body, with cells at each end elongated and fused to form ± stellate-globular tails 0.1-0.3mm long, the cells covering body elongate. Cotyledons lacking multicellular hairs or very occasionally with a few gland-headed hairs and with venation represented by midvein and a small number of poorly developed secondary veins.

Habitat: In coniferous or deciduous forests and thickets

Distribution: Japan (Hokkaido, Honshu)

Altitude: 800-2300m

Illustrations:

Notes

Rhododendron albrechtii is a phylogenetically isolated species of equivocal relationship. It is possibly most closely related to R. schlippenbachii, R. quinquefolium and R. pentaphyllum, being weakly linked with these species in at least some cladograms on the basis of its dimorphic stamens (present in R. schlippenbachii and slightly developed in R. pentaphyllum) and possibly also the loss of fringed seeds (see Cladistic Analysis). The species is here considered tentatively to be an isolated (and possibly cladistically basal) member of sect. Sciadorhodion. This placement agrees with that arrived at by M. Philipson (1980) on the basis of cotyledon characters. It is noteworthy that occasional multicellular gland-headed hairs similar to those of R. pentaphyllum, R. quinquefolium and R. schlippenbachii occur on R. albrechtii cotyledons in a varying but small proportion of different seedling populations (M. Philipson, 1970, 1980). The presence of such hairs may be an additional synapo-morphy linking this species with sect. Sciadorhodion. However, a cladistic relationship to R. vaseyi (of sect. Rhodora) can be hypothesized due to the presence of acuminate leaf apices in both species. The seeds of R. albrechtii have a small appendage (or tail) at each end, as do those of both R. vaseyi and R. canadense (a probable symplesiomorphy) and, like these species, the vegetative shoots (bearing alternate and not obviously 5-whorled leaves) develop from axillary buds associated with foliage leaves of the previous season (other likely symplesiomorphies). The phenetic closeness of R. albrechtii and R. vaseyi has been noted by Sargent (1888), Gray (1879), Rehder (1921a), and Wood (1961). It is likely that R. albrechtii diverged early in the evolutionary history of Rhododendron subgen. Pentanthera, and since nearly all features of this species are plesiomorphic, determining the species'cladistic relationships are difficult.

Nomenclature

Synonymy: Azalea albrechtii (Maxim.) Kuntze, Revis. Gen. PI. 2: 387 (1892). Type: Japan, Hakodate, in subalpine valley near Nodafu, 1861, C. Maximowicz (lecto. LE, n.v.).

Flags

Occurs in Countries: JP Altitude Ranges: 0 - 1,000m: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Pentanthera Habit: Non-Tree Fl. Colour: green, red

Judd, W.S. & Kron, K.A. (1995) A Revision of Rhododendron VI. Subgenus Pentanthera (Sections Sciadorhodion, Rhodora and Viscidula). Edinburgh Journal of Botany 52(1):22

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Rhododendron album Blume

Shrub to 1m. Twigs 3–4mm in diameter, rounded, densely covered with brown scales; internodes 1.5–8cm. Leaves 4–5 together in dense pseudowhorls. Blade 40–100 x 12–30mm, narrowly elliptic, acuminate; apex acute; margin entire, flat or slightly revolute, markedly so in dry specimens; base acutely tapering; moderately silvery scaly above initially, becoming glabrescent in the mature state; dull with dense, golden-brown scales beneath. Scales flat, with many touching or slightly overlapping each other, forming a continuous layer, the marginal zone wide in relation to the small darker centre, deeply and irregularly crenate to moderately lobed, disappearing in old leaves leaving depressed scale centres or small pits. Mid-vein distinctly impressed for the entire length above, and grooved near the base, strong and prominently raised beneath for almost the entire length; lateral veins 6–10 per side, irregular, spreading, straight below, anastomosing towards the margin, slightly raised above when dry, obscure beneath. Petiole 10–25 x 2–2.5mm, grooved above, very densely brown-scaly. Flower buds 10–13 x 5–7mm, green, with dense brown scales, sub-spherical but with a distinct c.3mm apiculus, the bracts all appressed but sometimes with a few basal, linear ones, spreading, but inwardly curling and with cataphylls around the base; basal bracts triangu­lar, very densely brown-scaly outside and with dense scales inside at the apex, other bracts ovate, densely brown-scaly outside and with a fringe of scales along the margins, glabrous inside. Bracteoles to 10mm, linear, scaly. Inflorescence 8–13-flowered in an open umbel, the flowers semi-erect to half-hanging. Pedicels 15–20 x c.1.25mm, slender, pink, densely scaly, the scales on short stalks and minutely, patently hairy. Calyx disc-shaped or triangularly lobed, the lobes 1–2mm, covered with, and fringed with, scales. Corolla 13–18 x 18–27mm, campanulate, cream or very pale yellow, without scent; tube 8–11 x 4–6 x 11–15mm, brown-scaly outside, glabrous inside except for a few long hairs near the base; lobes 8–10 x 9–13mm, sub-circular, erect or semi-erect and half overlapping, scaly outside except near the margins. Stamens exserted to c.4mm, at first, with the anthers curved inwards towards the centre of the flower, later regularly wide-spreading around the mouth, c.11mm; filaments linear, patently hairy in the basal 1⁄3, glabrous above; anthers c.1.8mm, broadly oblong. Disc hairy or glabrous. Ovary c.3 x 1.5mm, conical, densely scaly, with a mixture of purple-coloured and brown scales but without simple hairs, tapering distally; style 6–7mm, thick, mostly deflected to the lower side of the flower, curving towards the centre as the flower ages, scaly in the proximal ½ with both purple and brown scales, glabrous distally; stigma thick, deeply 5-lobed. Fruit 15–20 x 4–5mm, densely scaly, the valves curling back, the placentae weakly spreading and breaking away from the base. Seeds 5–6mm, without tails c.1mm, the longest tail 2.5mm.

Habitat: Epiphytic in montane forest. Locally common.

Distribution: Indonesia, W Java, Mts Salak, Gedeh, Telaga above Puntjak and Telaga Warna and vicinity, reported from C Java (Kedu: Dieng, coll. Junghuhn), but not recollected there recently.

Altitude: 1200-1700m

Notes

Latin – albus – white, alluding to the flower colour but not apt.

Nomenclature

Type: Zippelius s.n. Indonesia, Java, Mt Salak, Megame(n)dong (A, L).

Synonymy: Vireya alba (Blume) Blume, Bijdr. Fl. Ned. Ind. 1826. 855.

Flags

Occurs in Countries: ID Altitude Ranges: 1,000 - 2,000m Subgenus: Vireya Habit: Epiphyte, Non-Tree Fl. Colour: brown, cream, yellow

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:130

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Rhododendron alternans Sleumer

Shrub to 3m. Twigs 2–3mm in diameter, rounded, laxly stellate-scaly, early glabrescent and smooth; internodes 4–8cm. Leaves in loose pseudowhorls in the upper ½ of the internodes. Blade 25–40 x 12–20mm, elliptic or ovate-elliptic, more rarely sub-obovate; apex shortly and broadly sub-acuminate, or almost rounded, with a faint apical gland; margin pale, cartilaginous, entire or weakly crenulate with impressed scales; base broadly tapering or rounded, sometimes sub-truncate or sub-cordate, sub-densely scaly above but quickly glabrescent, sub-densely and persistently scaly below. Scales sub-stellate or obtusely lobed, marginal zone wide; centre minute, slightly impressed. Mid-vein broad proximally, impressed above, prominent in the lower ½ beneath, becoming hardly visible towards the apex of the blade; lateral veins c.5 per side, spreading, slightly conspicuous above only. Petiole 1.5–3 x 1–1.5mm. Outer bracts to 18 x 7mm, ovate, sub-acuminate or obtuse, inner ones ovate-oblong to sub-spathulate, all hairy outside and fringed with scales. Bracteoles to 15mm, linear, laxly hairy. Inflorescence a 3–4-flowered open umbel. Flowers hanging. Pedicels 15–20 x 1mm, slender, densely covered with reddish-brown sub-­stellate scales and very short white hairs. Calyx c.2.5mm in diameter, oblique, disc-shaped, margin obscurely lobed, scaly and very shortly hairy. Corolla 25–32 x 15–20mm, tubular, red, glabrous outside and in; tube 20–25 x c.4 x 6–7mm, cylindrical, straight, the base 5-pouched; lobes 7–9 x 7–9mm, spreading, obovate-spathulate or nearly circular. Stamens unequal, the longest nearly as long as the corolla; filaments linear, glabrous; anthers 2.7 x 1mm, oblongoid; bases sometimes shortly appendaged. Disc prominent, glabrous. Ovary c.4 x 2.5mm, thick, sub-ovoid to con­ical, densely covered with short, sub-patent white hairs and with scales between the hairs, abruptly contracted distally; style slender, glabrous, as long as the stamens; stigma sub-globose. Fruit 20–28 x c.5mm, sub-cylindrical, tapering at both ends, sub-densely hairy and laxly scaly.

Habitat: Terrestrial in shrubbery, or epiphytic in low forest. Common.

Distribution: Indonesia, C Sulawesi, summit of Mt Kambuno

Altitude: Around 3000m

Notes

Latin – alternans – alternating, presumably referring to the leaves which were originally described as partly opposite.

Not recollected and never cultivated.

Nomenclature

Type: Eyma 1363, 28 July 1937. Celebes (C), Masamba, top of Mt Kambuno, 2860m (L, A, BO, K).

Flags

Occurs in Countries: ID Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Vireya Habit: Epiphyte, Non-Tree Fl. Colour: red

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:212

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Rhododendron alticola Sleumer

Shrub or small tree to 3m. Twigs 2–4mm in diameter, appressed scaly at first, quickly glabrescent and smooth; internodes 1.5–2.5cm. Leaves 3–6 together in tight pseudo­whorls. Blade 30–90 x 12–25mm, obovate or elliptic; apex broadly tapering, obtuse to rounded, sometimes apiculate with a terminal gland; margin narrowly cartil­aginous, slightly revolute; base broadly tapering, rarely rounded; densely scaly at first on both sides, glabrescent above, laxly persistently scaly beneath. Scales small, marginal zone very thin, quickly disappearing, lobed; centre minute, dark and impressed. Mid-vein deeply impressed above, prominently raised below, often becoming broader near the base; lateral veins 6–8 per side, irregularly curved-upwards, anastomosing, faintly impressed in old leaves above, a little prominent beneath, reticulation lax, visible beneath only. Petiole 5–9 x 1–1.5mm, grooved above, flat, laxly scaly. Bracts to 12 x 5mm, ovate-acuminate, laxly scaly outside or glabrous. Bracteoles c.10mm, filiform below, slightly dilated distally. Inflorescence 3–6-flowered open umbels, the flowers hanging. Pedicels 8–20mm, slender, laxly to sub-densely scaly. Calyx c.4mm in diameter, disc-shaped, irregularly and shortly 5-lobed, glabrous. Corolla 20–60mm, tubular-funnel-shaped, bright red; tube 18–50 x c.4 x 7–12mm, laxly scaly outside, glabrous inside or laxly hairy, tube slightly to distinctly curved; lobes 12–15 x 10–13mm, spreading, broadly obovate-spathulate, sometimes with a few scales outside. Stamens clustered on the upper side of the flower, at the mouth or exserted to 6mm; filaments linear and laxly papillose-hairy proximally for c.2⁄3, glabrous and filiform distally; anthers c.2.5 x 1mm, oblong. Disc very prominent, glabrous. Ovary c.7 x 2mm, obovoid-cylindrical, densely scaly, but without hairs, gradually tapering distally; style slender, scaly at the base, glabrous distally, becoming slightly exserted; stigma thick, rounded. Fruit 40–50 x 5–7mm, sub-cylindrical, slightly curved, sub-densely scaly. Seeds 3mm, without tails c.0.8mm, the longest tail 1.3mm.

Distribution: Papua New Guinea, Fatima River, Spreader Divide, Bulldog Road, Mt Kaindi, Mt Missim, Mt Albert Edward, Mt Victoria, Mt Yule

Altitude: 2600-3600m

Notes

Latin – alte – high up; cola – dweller. Alluding to the high altitude at which it was found.

Van Royen & Kores (1982) regarded R. alticola as a widespread and polymorphic species, transferring it to series Javanica (of Sleumer 1966) as the leaves of many collections exceed 40mm in length. It is certainly very similar to R. culminicola and differs from that variable species in that the ovary is said always to be without hairs. Material in Edinburgh has been cultivated under this name since 1967; this was collected by Michael Black (no. 81) from the Fatima River area and agrees with the informal description in van Royen & Kores (1982) of the form from that area, except that it has hairs on the inside of the corolla tube. Hairs inside the corolla have also been found on specimens from Mt Yule and the Bulldog Road – these may represent a different taxon. A Woods specimen (3064A) from the Mt Albert Edward area has sparse hairs on the ovary also and may represent a hybrid. The hybrid R. alticola x R. spondylophyllum was collected by Paul Kores from Mt Victoria and it would be surprising if hybrids with R. culminicola did not occur. High altitude species tend to be the most difficult to cultivate. The ‘Black’ collection grows well, with beautiful deep red flowers which are for some time held semi-erect due to the persistence of the bracts at the base in a collarette.

Nomenclature

Type: Brass 4332, May–July 1933. New Guinea (SE), Mt Albert Edward, Central District, c.3600m (L, BO).

Flags

Occurs in Countries: PG Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Vireya Habit: Tree Fl. Colour: red

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:298

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Rhododendron alutaceum Balfour f. & W. W. Smith

Shrub, 0.6-4.5m. Leaves oblong to oblanceolate, 5-17 x 2-4cm, 2-6.2 x as long as broad, apex apiculate, base rounded to cuneate, lower surface with a bistrate indumentum, the upper layer ramiform-tomentose, ± continuous, pale brown and lanate or more felted and mid- to reddish-brown, or partially detersile and usually rufous, lower layer whitish and compacted; petioles 0.8—2cm, usually persistently brown-tomentose. Inflorescence 10-20-flowered; rhachis 10-18mm; pedicels 10-20mm, tomentose. Calyx 0.5-lmm, tomentose, lobes rounded. Corolla campanulate to funnel-campanulate, white to pink, with crimson flecks, sometimes with a purple basal blotch, 30—40mm. Ovary sparsely glandular and tomentose to almost glabrous, though with a few simple papillate hairs; style glabrous. Capsule 12-20 x c.5mm.

Habitat: Pine forests, cane brakes, open stony places

Distribution: China (SE Xizang, NW Yunnan, SW & C Sichuan)

Altitude: 3050-4250m

Flags

Occurs in Countries: CN Altitude Ranges: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: crimson, pink, purple, white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):348

Rhododendron alutaceum var. alutaceum

Leaf indumentum usually pale ochraceous brown, lanate with long fine ramiform hairs, continuous; ovary with a few papillae, otherwise ± glabrous

Notes

Closely resembling R. taliense but with at least a few papillae or ramiform hairs on the ovary. The type specimen is apparently a mixed gathering; part is referable to var. alutaceum and part to var. russotinctum.

Nomenclature

Type: China, NW Yunnan, Kari Pass, Yangtze/Mekong divide, 27°40'N, viii 1917, Forrest 13098 (holo. E; iso. K)

Synonymy: R. globigerum Balfour f. & Forrest, Notes R.B.G. Edinb. 13: 259 (1922). Type: China, SW Sichuan, Muli Mts, 28°12'N, 11-12000ft, vi 1918, Forrest 16376 (holo. E; iso. K). R. roxieanum Forrest var. globigerum (Balfour f. & Forrest) Chamberlain, Notes R.B.G. Edinb. 36: 119 (1978)

Rhododendron alutaceum var. iodes (Balfour f. & Forrest) Chamberlain

Leaf indumentum mid- to rufous-brown, not lanate, sometimes with upper layer discontinuous; ovary with a sparse indumentum of rufous ramiform hairs and glands. Leaf indumentum with a continuous felted upper layer composed of short fine usually mid-brown ramiform hairs.

Notes

Var. iodes closely resembles R. phaeochrysum var. levistratum but differs in the usually narrower leaves and the sparsely tomentose and/or glandular ovary.

Nomenclature

Synonymy: R. iodes Balfour f. & Forrest, Notes R.B.G. Edinb. 13: 49 (1920). Type: China, SE Xizang, Tsarong, on the Dokar La, Mekong/Salween divide, 12000ft, vi-vii 1918, Forrest 16745 (holo. E; iso. K)

Rhododendron alutaceum var. russotinctum (Balfour f. & Forrest) Chamberlain

Leaf indumentum mid- to rufous-brown, not lanate, sometimes with upper layer discontinuous; ovary with a sparse indumentum of rufous ramiform hairs and glands. Leaf indumentum with upper layer discontinuous, composed of ramiform rufous hairs.

Illustrations:

  • Rhododendron & Camellia Yearbook 25: f.58 (1970)
Notes

Var. russotinctum intergrades with both var. alutaceum and var. iodes

Nomenclature

Synonymy: R. russotinctum Balfour f. & Forrest in Notes R.B.G. Edinb. 11: 129 (1919). Type: China, W NW Yunnan, mountains N of Atuntzu, 28°25'N, 13000ft, vi 91, Forrest 13971a (holo. E). R. triplonaevium Balfour f. & Forrest, ibid. 13: 62 (1920). Type: China, NW Yunnan, Tseku, Soulie 1029 (iso. BM, E, K). R. tritifolium Balfour f. & Forrest, ibid. 13: 63 (1920). Type: W NW Yunnan, Mekong/Salween divide, 28°12'N, vii 1917, Forrest 14140 (holo. E; iso. K).

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Rhododendron amabile Sleumer

Shrub. Twigs rounded and densely scaly becoming glabrescent; internodes 2.5–9cm. Leaves 4 together in pseudowhorls, sub-sessile. Blade 25–60 x 12–28mm, broadly elliptic to elliptic; apex broadly tapering, sub-obtuse; margin slightly revolute; base sub-truncate, rounded to sub-cordate; at first scaly becoming glabrescent above, persistently and laxly scaly beneath. Scales irregularly dentate at margin, flat, each on top of a minute epidermal tubercle. Mid-vein flat or weakly impressed above, thick and very prominent beneath in the proximal 2/3, less so distally; lateral veins 7–8 per side, straight below, curved-anastomosing near the margin, hardly visible above, somewhat raised beneath, reticulation inconspicuous. Petiole 2–3 x c.1.5mm, scaly. Bracts to 14 x 9mm, ovate-acuminate, acute, outer ones scaly and sub-densely covered with hairs outside, inner ones hairy only. Bracteoles to 10 x 1mm, linear to sub-spathulate-linear, laxly hairy. Inflorescence 7–9-flowered. Pedicels 7–12 x c.0.5mm, densely scaly and shortly sub-patently greyish hairy. Calyx c.2.5mm in diameter, minute, membranous, wavy, irregularly fringed. Corolla trumpet-shaped, proximally white, pink-coloured distally; tube 30–33 x 2.5 x 3.5mm, cylindrical, straight, distinctly pouched at the base, laxly short-hairy and scaly outside, the scales completely disappearing by maturity, shortly hairy in the proximal ½ inside, glabrous distally; lobes 10–12 x 7–8mm, slightly spreading, obovate-spathulate, hairy outside at the base, otherwise glabrous, though distinctly ciliate. Stamens slightly exserted; filaments linear, hairy in the proximal 1⁄3, glabrous distally; anthers 1.8–2 x 0.7mm, oblong, base obtuse. Disc prominently 10-lobed, glabrous. Ovary 6–7 x 1.6mm, sub-cylindrical, densely hairy and scaly, abruptly narrowed distally; style hairy and scaly to nearly the top; stigma thick, conical-globose, just below the mouth.

Habitat: Said to be common in secondary forest on stony and peaty soil.

Distribution: Indonesia, Sulawesi (C), Masamba District near Limbung

Altitude: Around 1700m

Notes

Latin – amans – loving; a lovable rhododendron.

Known only from the type collection. Not cultivated.

Nomenclature

Type: Steup 206, 19 Aug. 1937. Celebes, Central, Masamba, Limbung-Porio, 1700m (L, BO).

Flags

Occurs in Countries: ID Altitude Ranges: 1,000 - 2,000m Subgenus: Vireya Habit: Non-Tree Fl. Colour: pink, white

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:169

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Rhododendron amagianum Makino

Tree, to 5m; young shoots densely covered with white soft hairs, later glabrescent. Leaves broadly ovate-rhombic, 4-9 x 3-9cm, apex acuminate, upper surface with long scattered brown hairs, lower surface with adpressed brown pubescent hairs, especially on midrib; petioles 5-10mm, densely adpressed-brown-pubescent. Inflorescence 1-3-flowered; pedicels 6-13mm, densely pubescent. Corolla open-campanu-late, 25-40mm, reddish-orange, upper lobe with darker flecks, lobes 25mm, oblong. Stamens 10, glabrous. Ovary densely brown-pubescent; style with white pubescent hairs at base. Capsule ovoid, 15-20mm, densely pubescent.

Distribution: Japan (Hondo, Idzu Peninsula)

Altitude: Around lOOm

Illustrations:

Notes

Closely allied to R. sanctum and possibly conspecific; differing in its often longer pedicels and in its red flowers. R. amagianum apparently flowers in mid July, about one month later than R. sanctum, and has an extremely restricted range.

Nomenclature

Synonymy: R. weyrichii Maxim, var. amagianum (Makino) Hatusima, Sci. Rep. Yokosuka City Mus. 15: 23 (1969)

Flags

Occurs in Countries: JP Altitude Ranges: 0 - 1,000m Subgenus: Tsutsusi Habit: Tree Fl. Colour: red

Chamberlain, D.F. & Rae, S.J. (1990) A Revision of Rhododendron IV Subgenus Tsutsusi. Edinburgh Journal of Botany 47(2):152

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Rhododendron amandum Cowan

Shrub, 1 -3-1 -6 m. Young growth loriform-setose. Leaves elliptic, broadly acute at the apex, 70 x 33 mm, upper surface dark green or brownish, somewhat rugose, elepidote except near the base, the base of the midrib loriform-setose, margins entire, sparsely loriform-setose, lower surface brownish with rather dense scales which are contiguous or up to their own diameter apart; petioles sparsely loriform-setose. Inflorescence 2-3-flowered, pedicels densely lepidote. Calyx conspicuous, deeply 5-lobed, the lobes ovate-oblong, c. 9 mm, lepidote on the outer surface, loriform-ciliate on the margins. Corolla funnel-campanulate, pale yellow, 38 mm, tube 20 mm, glabrous and very sparsely lepidote outside, sparsely pubescent inside. Stamens 10, filaments rather sparsely pubescent towards the base. Ovary densely lepidote, style impressed, very sparsely lepidote at the extreme base. Capsule unknown.

Distribution: China (SE Xizang)

Notes

Known only from the type collection.

Nomenclature

Type: S Tibet, ChayulChu, Natrampa, 11500 ft, 27 iv 1936, Ludlow & Sherriff1365 (holo. BM, iso. E)

Flags

Occurs in Countries: CN Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: yellow

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):42

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Rhododendron ambiguum Hemsley

Shrub, 1-5-5 m. Leaves narrowly ovate or obovate or narrowly elliptic, ± acute at the apex, cuneate-rounded at the base, 30-60(-80) x 15-32 mm, dark green and persistently lepidote above, densely lepidote beneath with contiguous or overlapping, dark brown, somewhat unequal, large, broadly rimmed scales; petiole, and midrib for a short distance from the base, pubescent. Inflorescences 3(-5)-flowered, pedicels lepidote and sometimes puberulent near the base, 10-15 mm. Calyx undulate or very weakly lobed, iepidote, sometimes filiform-acicular-ciliate. Corolla yellow, often with greenish or darker yellow spots on the upper lobes, 20-26 mm, tube 8-11 mm, variably lepidote outside, rarely elepidote. Stamens 10, filaments pubescent towards the base. Ovary lepidote, style usually glabrous, rarely puberulent at the base. Capsule lepidote, cylindric, (9~)11-13 mm.

Habitat: Thickets on hillsides

Distribution: China (C Sichuan)

Altitude: 2600-4500m

Illustrations:

Notes

Superficially similar to R. triflorum but distinguished by its greyish brown, shredding bark, large, denser leaf scales and the lack of indumentum on the corolla.

Nomenclature

Type: none cited, typifiable from the illustration which is based on material cultivated from seed collected by Wilson

Synonymy: R. chiengshienianum Fang, Ic. PL Omeiensium 1:1, t. 36 (1942). Type: China, Szechuan, Omei hsien, Mt Omei, 3000 m, 27 v 1940, Sun 2229 (iso. E)

Flags

Occurs in Countries: CN Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: green, yellow

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):78

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Rhododendron amesiae Rehder & Wilson

Very similar to R. concinnum, differing as follows: petioles with a dense indumentum of loriform hairs, young growth loriform setose; corolla c. 34 mm, tube c. 18 mm.

Habitat: Thickets

Distribution: China (NW Sichuan)

Altitude: 2300-3000m

Illustrations:

Notes

Known only from the type collection and material in cultivation

Nomenclature

Type: China, Szechuan, Mupin, 2300-3000 m, vi 1908, Wilson 3444 (iso. E)

Flags

Occurs in Countries: CN Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Rhododendron Habit: Non-Tree

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):76

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Rhododendron amundsenianum Handel-Mazzetti

Shrub to 50 cm. Leaves 9-18 x 5-9 mm, broadly elliptic or rotund, apex rounded with a short reflexed mucro, base truncate or broadly cuneate, undersurface a uniform rusty brown, the scales irregularly contiguous. Inflorescence c. 3-flowered, pedicels densely lepidote, 2-3 mm. Calyx 4-5 mm, lobes ovate with a central band of scales, margins densely ciliate. Corolla and stamens unknown. Style up to 15 mm, pubescent towards the base. Capsule lepidote, 5 mm.

Distribution: China (SW Sichuan)

Notes

Known only from very limited material (2 collections) and in need of further study when more material is available.

Nomenclature

Type: China, Szechuan, m. Lose-schan, nr. Ningvuen, c. 3900-4250 m, 16 iv 1914, Handel-Mazzetti 1414 (holo. W, iso. A)

Flags

Occurs in Countries: CN Subgenus: Rhododendron Habit: Non-Tree

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):100

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Rhododendron anagalliflorum Wernham

Dwarf prostrate or creeping shrub to 15cm. Twigs very slender, 0.5–0.7mm in diameter, densely covered with shortly stalked dendroid or sub-sessile stellate scales at first, warty in the older glabrescent parts; internodes 0.5–2.5cm. Leaves 3–5 together in tight pseudowhorls at the upper 3–4 nodes. Blade 3–7 x 1–2.5mm, elliptic or sub-obovate; apex sub-acute or obtuse; margin entire, flat; base broadly tapering, initially scaly on both sides, glabrous above at maturity, laxly and more persistently scaly beneath. Scales brown, flat or slightly concave; marginal zone rounded or obtusely lobed; centre small, slightly impressed. Mid-vein visible only near the base above and slightly impressed there, slightly raised and visible for a greater length beneath; lateral veins obscure. Petiole 0.5–1 x 0.3mm, not grooved, brown-scaly. Flower buds to 6 x 3mm, narrowly ovoid with an acute apex, pale brown or pink, laxly scaly outside, the bract tips slightly spreading. Bracts narrowly ovate-acuminate, laxly scaly outside and along the margins. Bracteoles 4–5mm, linear. Pedicels 6–7 x 0.75mm, very slender, densely covered with dendroid stellate scales and sparse white hairs. Flowers solitary. Calyx c.2mm in diameter, obliquely cup-shaped, shortly obtusely 5-lobed. Corolla 10–18 x 7–18mm, funnel-shaped, white flushed with reddish purple near the base; tube 5–7 x 3–5 x 5–7mm, laxly scaly outside, glabrous inside; lobes 5–8 x 4–5mm, elliptic, semi-erect or half-spreading, not overlapping when fully open. Stamens distinctly dimorphic, regularly arranged all round the mouth, the longest exserted to 1.5mm; filaments 8 and 6.5mm, pink, linear, glabrous; anthers c.0.7 x 0.4mm, oblong. Disc densely hairy along the upper margin. Ovary c.1.8 x 1mm, broadly sub-ovoid-cylindrical, densely covered with short, spreading hairs, less densely scaly between the hairs; style c.1.5 x 0.2mm, sparsely hairy at the base or to halfway; stigma green, thick-globose. Fruit 10–15 x c.2mm, fusiform, pink, shortly hairy and scaly. Seeds 3–4mm including the tails.

Habitat: In montane forest, open grassland or alpine shrubberies, epiphytic on moss on trees, or trailing over fallen logs

Distribution: Indonesia, New Guinea (W), Mt Carstensz. Papua New Guinea, Bismarck Mts and Wahgi–Jimmy Divide. New Britain: Mt Lululua, in the Pomio subdistrict.

Altitude: 1190-3500m

Notes

Latin – Anagallis (Primulaceae); florum – flower. With flowers like an Anagallis (pimpernel).

This species was for some time confused with R. rubineiflorum (for differences see under that species).

Nomenclature

Type: Kloss s.n. New Guinea (W), Ascent to Mt Carstensz Camp VIb (BM).

Synonymy: R. linnaeoides Schltr., Bot. Jahr. 1917. 55: 144, f.2.

Flags

Occurs in Countries: ID, PG Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Vireya Habit: Epiphyte, Non-Tree Fl. Colour: purple, red, white

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:147

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Rhododendron angulatum J.J.Sm.

Shrub to c.75cm. Twigs robust, rounded, laxly scaly. Leaves c.5 in pseudowhorls. Blade 110–180 x 35–58mm, ovate-elliptic; apex gradually long-acuminate, acute; margin flat or weakly recurved; base obtuse, rounded or slightly cordate; glabrescent above with age, sub-densely scaly beneath. Scales stellately lobed in the marginal zone; centre impressed, leaving minute pits when scales are gone. Mid-vein narrowly grooved above, thick and obtusely prominent beneath in the proximal part; lateral veins 12–15 per side, ascending, anastomosing, very slightly raised or impressed above, obscure beneath; reticu­lation obscure. Petiole 10–12 x 3mm, strong, grooved above, flattened, transversely rugulose, minutely scaly. Inflorescence of c.6 flowers. Pedicels 40–50 x c.2.5mm in diameter, laxly minutely scaly, more densely so below the calyx, without hairs. Calyx c.4.5mm in diameter, oblique, obtusely and inconspicuously 5-angular, ciliate. Corolla 55–66mm, funnel-shaped, lobed in the upper 2⁄3, red, fleshy; tube c.20 x 8 x 9mm, sparsely minutely scaly outside, laxly hairy inside, distinctly 5-angular or pouched at the base outside, deeply 5-grooved lengthwise in the proximal part inside, the ribs extending upwards to the middle of the corolla lobes; lobes 35–40 x c.20mm, sub-ovate-elliptic, obtuse, spreading. Stamens nearly as long as the corolla; filaments linear and shortly patently hairy below, narrower and glabrous distally; anthers 5.5–6 x c.1mm, linear-oblong, obtuse at the base. Disc promi­nent, practically glabrous. Ovary c.10 x 3mm, conical-cylindrical, densely covered with thick, nearly round, scales, no hairs, tapering distally; style c.48mm, scaly and sparsely minutely hairy, or nearly papillose, at the base, glabrous distally; stigma thick-rounded.

Habitat: Common terrestrial in shady peat swamps

Distribution: Indonesia, New Guinea (W), Oranje Mts, Mt Goliath.

Altitude: Around 1500m

Notes

Latin – angulatus – angled, alluding to the distinctly angled corolla.

Known only from the type collection

Nomenclature

Type: De Kock 177. New Guinea (SW), Mt Goliath, Juliana Range, 1500m (BO).

Flags

Occurs in Countries: ID Altitude Ranges: 1,000 - 2,000m Subgenus: Vireya Habit: Non-Tree Fl. Colour: red

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:296

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Rhododendron annae Franchet

Shrub, 0.5-6m. Leaves coriaceous, elliptic to oblanceolate, 6.5-15 x 2-3.5cm, 3.5-4.5 x as long as broad, apex acuminate, base cuneate to rounded, margin usually slightly undulate, both surfaces glabrous though with red punctate hair bases overlying the veins beneath; petioles l-3cm, glabrous. Inflorescence 7-12(-17)-flowered; rhachis 5-35mm; pedicels 15-30mm, densely stipitate-glandular. Calyx l-2mm, lobes rounded, gland-fringed. Corolla open-campanulate, lacking nectar pouches, white with a rose flush, with or without purple flecks, 25—40mm. Ovary densely glandular; style glandular to tip. Capsule 13-25 X 6-8mm.

Distribution: China (W Yunnan, ?Guizhou), NE Upper Burma

Notes

The type of R. annae does have smaller flowers than is usual for the species and this has been used as the main diagnostic feature to separate R. annae from R. laxiflorum. The holotype of R. hardingii has equally small flowers however, while the isotype material has larger flowers and matches the type of R. laxiflorum.

Bodinier's type of R. annae is supposed to have been collected in Guizhou near Guiyang. If this is confirmed, then this species has a surprisingly disjunct distribution; all the remaining material comes from Mid-West Yunnan.

Nomenclature

Type: China, ?Guizhou, Montagne de Lou Tsang Kuan, 1500m, 7 v 1897, Bodinier 1588 (holo. E; iso. K).

Synonymy: R. laxiflorum Balfour f. & Forrest, Notes R.B.G. Edinb. 13: 50 (1920). Type: China, W Yunnan, Shweli/Salween divide, 8000ft, v 1919, Forrest 17953 (holo. E; iso. K). R. hardingii Tagg, Notes R.B.G. Edinb. 16: 196 (1931). Type: China, W Yunnan, 3 days march S of Tengyueh, 24°20'N, 98°33'E, 6000ft, Harding (Forrest) 26313 (holo. E).

Flags

Occurs in Countries: CN, MM Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: purple, rose, white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):293

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Rhododendron anthopogon D. Don

Small shrub to 1 m, often closely and intricately branched. Leaf-bud scales persistent or not. Leaves ovate or elliptic, rarely almost orbicular, (10-)14-35 x 8-16 mm, rounded to the base and to the subacute'mucronate or rarely slightly emarginate apex, above dark green, lepidote or elepidote, beneath dark brown (rarely rather pale) with dense, overlapping scales in 2-3 tiers, those of the lowest tier as dark as, or darker than the rest. Inflorescence dense, many-flowered, pedicels short, lepidote, puberulent or entirely glabrous. Calyx lobes oblong, 3-5-4-5 mm, usually somewhat lepidote outside, margin loriform-ciliate, inner surface variably pubescent. Corolla usually white or pink, rarely cream or yellowish, tube 6-12 mm, lobes 4-7-5 mm, glabrous and elepidote outside, densely pilose within the tube. Stamens (5-)6-8(-10). Ovary lepidote. Capsule 4-5 mm, lepidote, scarcely exceeding the calyx.

Notes

Two subspecies may be recognised. Though they differ essentially in only one character, they do show geographical replacement

Flags

Occurs in Countries: BT, CN, IN, NP Altitude Ranges: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: cream, pink, white, yellow

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):158

Rhododendron anthopogon subsp. anthopogon

Habitat: Open slopes and hillsides

Distribution: Nepal, India (Uttar Pradesh, W Bengal, Sikkim, Arunachal Pradesh), Bhutan, China (S Xizang)

Altitude: 3350-4900m

Illustrations:

  • Schneider, 111. Handb. Laubh. 2:319 (1909)
Nomenclature

Type: Nepal, in Alpe immensa nivosa, Gossain Than Nepalensium dicta, Wallich (holo. K)

Synonymy: R. haemonium Balfour f. & Cooper, Notes R.B.G. Edinb. 9:283 (1916). Type: Bhutan, Pumo La, Timpu, 13000 ft, 15 v 1915, Cooper 3903 (holo. E). R. anthopogon var. haemonium (Balfour f. & Cooper) Cowan & Davidian, Rhodo. Yearbook 2:68 (1947)

Rhododendron anthopogon subsp. hypenanthum (Balfour f.) Cullen

Habitat: Open slopes and ledges, rarely in sparse forest

Distribution: India (Kashmir, Himachal & Uttar Pradesh), Nepal, Bhutan

Altitude: 3350-4500m

Illustrations:

  • Royle, III. Bot. Himal. t. 64 (1839)
Notes

Essentially a western vicariant of subsp. anthopogon, but with a distinct outlier in Bhutan

Nomenclature

Synonymy: R. hypenanthum Balfour f., Notes R.B.G. Edinb. 9:291 (1916) Type: described on the basis of a number of syntypes from the W Himalaya (all at E)

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Rhododendron anthopogonoides Maximowicz

Shrub to 1-6 m. Leaf-bud scales deciduous. Leaves ovate-elliptic, (20-)25-40 X (10—) 11 —21 mm, rounded at the base, rounded to somewhat tapered to the mucronate apex, sparsely lepidote or elepidote above, beneath pale brown with scales which are all borne ± at one level, overlapping, plastered to the surface, all with well developed domed centres and narrow, scarcely lacerate rims. Inflorescence dense, many-flowered. Pedicels pubescent, elepidote. Calyx lobes 3-4-5 mm, oblong-obovate, glabrous and elepidote outside, margin erose and with a few scales, glabrous within. Corolla white or greenish white, rarely flushed pink, tube 5-10 mm, lobes relatively small, 1-5-3 mm, scarcely overlapping, densely pilose at the throat and inside the tube. Stamens 5. Ovary lepidote, sometimes pubescent. Capsule lepidote, 4-4-5 mm

Habitat: Scrub and forest margins

Distribution: China (Quinghai, Gansu)

Altitude: 3050-3350m

Illustrations:

Notes

Very distinct in its scale type and its very dense inflorescences of flowers with curiously solid-looking corollas with short lobes, and characteristic calyces.

Nomenclature

Type: China occidentalis, Terra Tangutica (prov. Kansu), 1872, Przewalski (iso. E)

Flags

Occurs in Countries: CN Altitude Ranges: 3,000 - 4,000m Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: green, pink, white

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):163

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Rhododendron anthosphaerum Diels

Shrub or small tree, 3-12m. Leaves elliptic-obovate to oblong, 6-16 x 2-4.5cm, (2.5-)3-4 x as long as broad, apex acuminate to acute, base ± cuneate, margin not undulate, upper surface glabrous when mature, lower surface ± glabrous, with a few red punctate hair-bases overlying the veins;petioles l-2cm, glabrescent. Inflorescence dense, 10-15-flowered; rhachis 5-10mm; pedicels 10-15mm, sparsely rufous-tomentose. Calyx l-2mm, glabrous to stipitate-glandular. Corolla 6-7-lobed, tubular-campanulate, with nectar pouches, glabrous within, rose-magenta to crimson, occasionally magenta-blue or pale peach, with a variable amount of crimson flecks, with or without a basal blotch, 30-45mm. Ovary usually glabrous, occasionally with a few rufous hairs; style glabrous. Capsule 20-25 x c.5mm.

Habitat: Open rocky slopes, deciduous woodland, etc.

Distribution: China (Yunnan, SE Xizang), NE Upper Burma

Altitude: 2700-4000m

Illustrations:

Notes

R. anthosphaerum is a variable species, both in leaf shape, and in corolla size and colour. Several entities may be recognised within the species but complete intergradation apparently occurs. The names used below are given only as a guide without implying any format taxonomic status. 1. Leaves elliptic, apex ± acute..................R. anthosphaerum sensu stricto 4- Leaves oblong to obovate, apex rounded and apicuiate....................-... .2 2. Leaves up to 8cm long............................................R. gymnogynum + Leaves 8-16cm long.................................................................3 3. Corollac.30mm, blue-magenta...................................R. chawchiense + Corolla 35 -45mm, crimson to rose-magenta .,....................R. eritimum I am uncertain as to how far the four entities are differentiated geographically, a problem that can only be resolved by detailed population sampling. It is clear however that plants matching the types of both R. eritimum and R. anthosphaerum occur together on the Sungkwei Pass and in the Lichiang Snow Range. However, plants matching the type of R. eritimum appear to be more frequent in the northern part of the species'range.

Nomenclature

Type: China, Yunnan, ascent to the Sungkwei Pass, 11000-12000ft, iv 1906, Forrest 2042 (holo. E;iso. K).

Synonymy: R. eritimum Balfour f. & W. W. Smith, Trans. Bot. Soc. Edinb. 27: 190 (1917). Type: China, E NW Yunnan, mountains of the Chungtien Plateau, 9000ft, iii 1914, Forrest 12416 (holo. E; iso. BM). R. hylothreptum Balfour f. & W. W. Smith, ibid. 27: 195 (1917). Type: China, E NW Yunnan, summit of the Sungkwei Pass, 11000- 12000ft, v 1910, Forrest 5848 (holo. E; iso. K). R. gymnogynum Balfour f. & Forrest, Notes R.B.G. Edinb. 13: 47 (1920). Type: China, W Yunnan, Shweli/Salween divide, 11000ft, v 1918, Forrest 17495 (holo. E; iso. K). R. heptamerum Balfour f. in Notes R.B.G. Edinb. 13: 48 (1920). Type: NE Upper Burma, above Hpimaw, 8500-9000ft, iv 1919, Forrest 17827 (holo. E; iso. K). R. chawchiense Balfour f. & Farrer, Notes R.B.G. Edinb. 13:247 (1922). Type: NE Upper Burma, Chawchi Pass, 10500ft, 15 v 1920, Farrer 1552a (holo. E; iso. K). R. persicinum Handel-Mazzetti, Akad. Wiss. Wien Math.-Naturwiss. KL, Anz. 60: 97 (1924). Type: China, NW Yunnan, in montium inter Dali et Hodjing, silvis temperatis jugi Dsuningkou, 3050-3350m, 27 v 1915, Handel-Mazzetti 6549 (iso. A, E).

Flags

Occurs in Countries: CN, MM Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Tree Fl. Colour: crimson, magenta, peach, rose

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):303

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Rhododendron aperantum Balfour f. & Kingdon-Ward

Dwarf matted shrub, 0.3-0.6(-1.5)m; young shoots with a floccose tomentum; perulae persistent. Leaves obovate to oblanceolate, 3-6.5 x 1.4-2.4cm, 1.7-2.6 x as long as broad, apex rounded, apiculate, base ± cuneate, upper surface glabrous, lower surface papillate, glaucous, usually glabrous at maturity though sometimes with vestiges of reddish-brown or whitish indumentum persisting on the main veins and midrib; petioles broad, 0.3-0.6cm, usually with a floccose indumentum when young. Inflorescence 4-6-flowered; rhachis c.2mm; pedicels 15-30mm, floccose-tomentose, also with long dendroid hairs. Calyx 3-6mm, cupular, lobes glandular-ciliate, otherwise glabrous. Corolla thin, tubular-campanulate, white or yellow flushed pink to orange or rose, (30-)35—45mm. Ovary coarsely rufous-tomentose with a few glandular setae. Capsule 8-15 x c.6mm.

Habitat: Cliffs, meadows

Distribution: NE Upper Burma & adjacent China (NW Yunnan)

Altitude: 3600-4500m

Notes

Plants with a more persistent though patchy indumentum, probably hybrids of R. aperantum, have been referred to R. aperantum var. subpilosum Cowan (Notes R.B.G. Edinb. 20: 84, 1940). They are as follows: Forrest 25596 (type-holo. E), 25563, 25757, 25878.

Nomenclature

Type: NE Upper Burma, Chawchi Pass, 12000ft, vii 1921, Farrer 1671 (holo. E; iso. K).

Flags

Occurs in Countries: CN, MM Altitude Ranges: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: orange, pink, rose, white, yellow

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):400

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Rhododendron apiense Argent

Shrub to 1m. Twigs c.4mm in diameter, green, rounded, laxly to sub-densely, pale-brown scaly and minutely, sparsely shortly patently hairy; internodes 2–12cm. Leaves loosely spirally arranged along the stem. Blade 50–100 x 43–60mm, broadly ovate or ovate-elliptic, occasionally broadly elliptic; apex obtuse, rarely rounded and mucronate but without an obvious apical gland; margin entire, flat, with a thin (c.0.5mm), reddish-purple edge; base distinctly cordate, occasionally broadly tapering and then with translucent auricles at the base of the lamina; glabrescent above, laxly and more persistently scaly beneath. Scales stellate, pale-brown, marginal zone appressed to the leaf surface; centres small and impressed. Mid-vein strongly raised above for about ¾ of the length of the leaf, slightly raised beneath or shallowly impressed in the proximal ½; lateral veins 7–10 per side, spreading almost perpendicularly, strongly raised above, the leaf surface deeply sulcate between the veins, dis­appearing before the margin, reticulation weak or obscure. Petiole 10–23 x 4–5mm, reddish-purple, rounded above, without a groove, sparsely to sub-densely scaly. Flower buds ovoid, 20–35 x 15–22mm, bracts firmly appressed except for a very short point. Outer bracts translucent, truncate to emarginate, almost glabrous, with just a few small scales outside but without any on the margins. Inflorescence a 5–8-flowered open umbel, the flowers held horizontally. Pedicels 34–38 x c.3mm, shortly, white, patent-hairy and with a few papillae towards the distal end but without scales. Calyx green, glabrous or with a few low, irregular papillae. Corolla 55–65 x 50–60mm, bright golden yellow, often flushed with orange on the tube and around the edges of the lobes, without scent; tube c.30 x 12 x 22mm, funnel-shaped, glabrous outside but densely shortly white, patent-hairy in the proximal ½ inside, conspicuously 5-lobed at the base; lobes 35 x 27mm, spreading almost at a right angle and overlapping to over halfway, glabrous. Stamens irregularly spreading around the mouth of the flower, occasionally in two groups, slightly dimorphic; filaments white, densely white hairy proximally, the hairs thinning distally and becoming glabrous for the uppermost 2⁄3; anthers c.4 x 1mm, arching inwards, tapering towards the base which is distinctly apiculate. Disc purplish-brown, lobed, shortly white hairy on the upper side. Ovary 10 x 5mm, green, sparsely patently white hairy and with a few rounded silvery scales, abruptly tapering distally; style 20 x 1.5mm, glabrous, green, slightly broadened to the pink, circular but 5-lobed stigma. Fruit 20–30 x 8–10mm, green or flushed red, often flecked with white, fusiform. Seeds c.3mm, without tails 0.8mm, the longest tail 1.5mm.

Habitat: Common in the sub-alpine shrubbery of the summit ridge, growing on deep peat which overlies limestone.

Distribution: Malaysia (Borneo), Sarawak, 4th Division, Mulu National Park, Mt Api.

Altitude: Around 1600m

Notes

Named after Mt Api, the mountain where it was found, which in the Malaysian language means ‘mountain of fire’. This is the only known locality of this species, which in addition has fiery-coloured flowers.

Rhododendron apiense is a peculiar species somewhat reminiscent of R. intranervatum Sleumer (from southern Sarawak) in having broad, sulcate leaves but it has sub-densely scaly (and minutely hairy), not laxly scaly young twigs, the ovary is only sparsely patently hairy, compared with the densely appressed hairy ovary of R. intranervatum, and it is much less sulcate. The mid-vein is only slightly raised beneath in this species, being level with the surface from about the midpoint of the leaf, often from the base, whereas in R. intranervatum it is strongly raised underneath to the apex. It differs from R. javanicum ssp. brookeanum, to which it is probably most closely related, in that the leaves are less than twice as long as wide with most leaves having a cordate base. It has distinctly basally apiculate anthers and a broader ovary with a shorter broader fruit. Apart from the distinctive leaf shape, the flowers differ from R. javanicum ssp. brookeanum in having larger, much more overlapping lobes and it grows at higher altitude than most forms of this species. Introduced into cultivation in Edinburgh in 1978, it is a lanky shrub which did not flower well until it was quite large and even then it has not produced the truly magnificent flowers which it did in the wild. It is still an attract­ive species and it is possible that it may perform better in climates with stronger light.

Nomenclature

Type: Argent RBGE 19781745, 22 May 2001. Sarawak, 4th Division, G. Api (SAR, E).

Flags

Occurs in Countries: MY Altitude Ranges: 1,000 - 2,000m Subgenus: Vireya Habit: Non-Tree Fl. Colour: orange, yellow

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:261

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Rhododendron apoanum Stein

Erect shrub to c.1m, commonly branching from the base and branching profusely above as well. Twigs rounded, densely covered with dark-brown scales but these becoming paler and giving the stems a grey appearance with age. Leaves 3–6 together in loose pseudo­whorls, 2–7cm apart. Blade 30–110 x 10–40mm, elliptic to obovate-elliptic, variable in shape and size; apex shortly acuminate, sub-acute or obtuse; margin flat or slightly revolute, often irregularly somewhat crenate or dentate in the distal part; base broadly to narrowly tapering, dull silvery-green above often with a somewhat bluish tinge from a distance, initially densely scaly on both sides, those above predominantly silvery but with visible brown centres to the largest scales, glabrescent with age; below, densely and persistently brown-scaly, but often with narrow areas of the leaf surface visible between the scales. Scales with broad striate flanges and large swollen centres, the largest scales well spaced, with large dark centres. Mid-vein slightly impressed above, very prominent beneath in the lower part of the lamina; lateral veins 6–7 per side, irregularly spreading, the upper ones straight, all anastomosing, very slightly depressed above in fully mature leaves, somewhat raised or only faintly visible beneath, reticulation hardly visible. Petiole 9–15 x 2–3mm, weakly grooved distally, densely brown-scaly. Flower buds to 17 x 12mm, ovate, broadly pointed, with all bracts firmly appressed, purple or green. Bracts ovate to sub-circular, glabrous except for the fringe of simple white hairs and a patch of overlapping brown scales on the outside near the apex, which often extend down the middle line. Flowers 6–15 in an open umbel. Bracteoles filiform, shortly patently hairy and with a few scales especially towards the apex. Pedicels 7–11 x c.1mm, densely scaly. Calyx c.2mm in diameter, disc-shaped, covered in brown scales. Corolla 16–20 x 16–20mm, pinkish-orange; tube 13–18 x 4–7 x 5–9mm, straight, often somewhat 5-angled, glabrous or very laxly scaly outside, at least at the sinuses of the lobes; lobes 4–7 x 5–11mm, spreading horizontally or sometimes a little reflexed, broadly rounded or emarginate. Stamens at first clustered in the centre of the flower later spreading irregularly round and reaching or slightly exceeding the mouth of the tube; filaments linear, flat, glabrous; anthers broadly oblong, c.1.7mm. Disc green, glabrous or with a few scales on the upper side. Ovary 4–5 x c.2mm, sub-ovoid-conical, densely scaly; style as long as or shorter than the ovary, thick, scaly at the base, glabrous in the upper ½; stigma thick, rounded. Fruit 20–25 x 3–4mm, spindle-shaped. Seeds 5–6mm, without tails 0.8–0.9mm, the longest tail 3mm.

Habitat: Mostly epiphytic in moss forest on peaks and ridges

Distribution: Philippines, Mindanao, Davao Province, Mt Apo, Mt McKinley. Bukidnon Province, Mt Lipa, Katanglad Mts. Agusan Province, Mt Urdaneta. Common on Mt Apo

Altitude: 1380-2930m

Notes

Named after Mt Apo where it was first collected, the highest mountain in the Philippines.

Copeland (1929) discusses the existence of two forms which had been suggested by Elmer (1911), one having slightly larger, entire, spreading leaves, the other with smaller leaves, ‘feebly dentate towards the apex, and tend[ing] to ascend strictly’. He concludes ‘that not even a varietal distinction can be made’ as the flowers are identical. In cultivation in Edinburgh there are two forms with differently coloured flower buds – purple and green – but with no other visible difference. This species might be regarded as an extreme variant of the R. malayanum complex but it is distinct in the smaller flowers which have a regular, circular or slightly 5-sided tube, not the laterally compressed tube characteristic of R. malayanum, as well as a shorter style. It is distinct from the only other Malayo­vireya so far known from the Philippines – R. nortoniae – by the much shorter flowers which are only ½ as long as in that species. Rhododendron apoanum was described and figured in the Gartenflora (Stein 1885) but the colour plate would appear to have been painted from a herbarium collection with directions from the collector as to the colours; there is no indication that it was cultivated. It took over 100 years to realise the horticultural promise of this species when it was finally introduced to cultivation via Edinburgh in 1993 from material collected on Mt Apo. It is one of the easiest species of this section to grow and flowers freely several times a year, the small size of the flowers being made up for by the freedom with which they are produced and the very attractive bluish-green aspect of the foliage.

Nomenclature

Type: Schadenberg, Feb. 1882. Philippines, Mindanao, Mt Apo (B†, neotype Elmer 11386 the same locality L, A, BM, E, K, NY).

Flags

Occurs in Countries: PH Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Vireya Habit: Epiphyte, Non-Tree Fl. Colour: pink

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:112

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Rhododendron apricum P.X.Tan

Shrub; young shoots densely spreading-glandular-pubescent and setulose. Leaves dimorphic, coriaceous; spring leaves elliptic-oblong, 3.5-3.8 x 1.5cm, c.2 x as long as broad, apex shortly acuminate, margins entire; upper surface with lamina soon glabrescent, lower surface with a yellowish brown pubescence and a few short strigose hairs; summer leaves elliptic-oblong to linear, 15-18 x c.7mm, otherwise as for spring leaves; petioles 2-2.5mm, densely spreading-setulose and glandular pubescent. Inflorescence c.I4-flowered, pedicels 5-7mm, densely strigose. Calyx strigose, lobes small, triangular. Corolla narrowly funnel-shaped, rose-red, c.l8mm; tube 10mm, 2.5mm at base, 4mm broad below lobes. Stamens 5, filaments glabrous. Ovary setose; style glabrous. Fruit not known.

Distribution: China (Fujian)

Illustrations:

Notes

Allied by the author to R, falcinellum, a species treated by us as a synonym of R. rufulum, but differing from the latter in the yellowish brown leaf indumentum, etc.

Nomenclature

Type: China, Fujian, Shanghang Xian, Wong-Yong, 400-500m, 13 v 1974, L.G. Li (L.K. Lee) 740740 (holo. Inst. Mat. Med. Fujian)

Flags

Occurs in Countries: CN Subgenus: Tsutsusi Habit: Non-Tree Fl. Colour: rose

Chamberlain, D.F. & Rae, S.J. (1990) A Revision of Rhododendron IV Subgenus Tsutsusi. Edinburgh Journal of Botany 47(2):102

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Rhododendron araiophyllum Balfour f. & W. W. Smith

Shrub or small tree, 1.5—6.5m. Leaves sub-coriaceous, elliptic to oblanceolate, 5.5-13 x 1.8-3.2cm, 3-5 x as long as broad, apex acute to cuspidate, base cuneate, margin plane to slightly undulate, upper and lower surfaces glabrous when mature, punctate hair-bases apparently lacking; petioles 0.7-1.5cm, fioccose-tomentose. Inflorescence lax, 5—10-flowered; rhachis c.5mm; pedicels 15-20mm, slender, smooth to minutely hairy. Calyx l-2mm, lobes rounded, glabrous to sparsely ciliate. Corolla open-campanulate, nectar pouches lacking, glabrous within, white flushed rose, with a basal blotch, sometimes also with purple flecks, 28-35mm. Ovary with a sparse covering of short white simple hairs; style glabrous. Capsule 10—16 x 3—4mm.

Habitat: Mixed forests

Distribution: China (Mid W Yunnan), ne Upper Burma

Altitude: 2300-3350m

Notes

Distinguished from R. annae by its glabrous style and the lack of punctate hair-bases.

Nomenclature

Type: China, W Yunnan, Shweli/Salween divide, 9000-lOOOOft, vi 1913, Forrest 11918 (holo. E; iso. BM, K).

Flags

Occurs in Countries: CN, MM Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Hymenanthes Habit: Tree Fl. Colour: purple, rose, white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):294

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Rhododendron arborescens (Pursh) Torr.

Shrub or small tree to 6m tall, usually non-rhizomatous; young twigs yellow-brown or rarely red-brown, glabrous or rarely very sparsely covered with unicellular hairs. Vegetative bud scales glabrous abaxially; margin unicellular-ciliate. Leaf blade membranaceous, ovate or obovate to elliptic, (4.5-)4.8-7.8(-10.5) x (1.6-) 1.9-2.6(-3.0)cm; base acute to oblique; apex acute to obtuse, often mucronate; adaxial surface glabrous, the midvein sparsely to densely covered with unicellular hairs; abaxial surface glabrous, sometimes also glaucous, the midvein sparsely covered with multicellular eglandular hairs, occasionally glabrous; margin entire, ciliate with multicellular eglandular hairs; petiole (0.2-)0.4-0.9(-1.6)cm long; glabrous or sparsely covered with multicellular eglandular hairs. Flower bud scales chestnut brown; abaxial surface glabrous or rarely with very sparse unicellular hairs; margin unicellular ciliate. Flowers appearing with the leaves or after they have expanded; Inflorescence a shortened raceme of 3 to 7 flowers. Pedicels (0.6-)1.0-1.6 (-2.1)cm long, sparsely to densely covered with unicellular and multicellular gland-tipped hairs, occasionally only with multicellular eglandular or gland-tipped hairs, rarely glabrous. Sepals less than 0.1-0.5(-0.8)cm long, often varying in length on the same flower; margins glandular-fim-briate and setose or only glandular-fimbriate, rarely only setose; abaxial surface glabrous to sparsely covered with multicellular gland-tipped hairs, eglandular hairs or with both, rarely additionally covered with unicellular hairs. Corolla white, fragrance sweet, with a cinnamon quality, the tube longer than the limb and gradually expanding into it; upper corolla lobe (1.0-)1.3-1.9(-2.1) x (0.7-)0.9-1.4(-1.8)cm; lateral lobes (1.2-) 1.4-2.0(-2.4) x (0.5-)0.6-0.9 (-1.2)cm; corolla tube (2.0-)2.3-2.9(-3.3)cm long, 0.2-0.5(-0.6)cm wide at base; outer surface of corolla sparsely covered with unicellular hairs and multicellular gland-tipped hairs that continue in lines up the corolla lobes; inner surface of corolla sparsely to densely covered with unicellular hairs. Stamens (4.4-)5.3-6.9(-8.2)cm long, with dense terete or flattened unicellular hairs on proximal (2.7-)3.0-3.8(-4.5)cm of filament, exserted (2.3-)2.9-4.3(-5.0)cm beyond throat of corolla. Style (5.3-)5.6-6.9(-7.5)cm long, exserted (3.2-)3.6-4J(-5.4)cm beyond throat of corolla, with dense unicellular hairs on proximal (0.0-)0.2-1.4(-2.6)cm; stigma 0.1-0.3cm wide. Ovary (0.2-)03-0.4cm long, 0.1-0.3cm wide at the base, densely covered with multicellular glaAd-tipped hairs and unicellular hairs. Capsules (1.1ó)1.2ó1.7 x 0.5-0.8cm, ovate, sparsely covered with unicellular hairs and moderately covered with multicellular gland-tipped hairs. S eeds pale to dark chestnut brown, ovate or elHptic to fusiform, (0.8-)l.l-1.6(-2.0) x (0.4-)0.6-1.0 (-l.l)mm,tody(0.7-)0.8-1.8 of the seed, the cells short with transverse end-walls orisodlametric.

Habitat: Along mountain streams, shrub balds and moist woods.

Distribution: USA: West Virginia to Tennessee, North Carolina, Georgia and adjacent Alabama.

Altitude: 300-1500m

Illustrations:

Notes

Rhododendron arborescens also hybridizes with R. cumberlandense and hybrids have been collected especially on Gregory Bald, Blount Co., Tennessee and in Jackson Co., Alabama. These hybrids vary considerably in morphology, from glabrous, white-flowered plants with unicellular-clliate bud-scale margins to pubescent, pink or reddish-flowered plants with glandular bud-scale margins. Putative hybrids also occur between R. arborescens and R. cumberlandense In Morgan County, Tennessee and in Union and Walker Counties, Georgia. Possible hybrids between R. arborescens, R. viscosum and J?, cumberlandense occur on Gregory Bald, Blount Co., Tennessee.

Rhododendron arborescens is most closely related to R. viscosum, and can be distinguished from It by the glabrous, yellow-brown branchlets, the red style and filaments which contrast with the white corolla and the distinctive seeds that lack a loose, expanded testa. Rhododendron arborescens is sympatric with R. viscosum and blooms during the same time of year. Both species are often found growing In close proximity to each other and hybridize occasionally, although these hybrids are sometimes difficult to detect. Reproductive Isolation may be related to pollinators as the fragrance of the two species is quite different and the flowers of R. viscosum have concolorous styles and filaments.

Chromosome number: 2n = 26 (JanaM-Ammal et al., 1950; Li, 1957)

Flowering from May to August, occasionally as early as April or as late as September.

Rhododendron arborescens is quite uniform morphologically throughout its range. The most noticeable variation occurs In leaf size and glaucousness which appear to be a function of habitat. Rehder (1921) described one form as a variety (R. arborescens var. richardsonii) which Is a smaU-leaved, compact form found In exposed situations on the tops of balds or mountains In the Appalachians.

Nomenclature

Synonymy: Azalea viscosa Marshall, Arbust. Amer. 15 (1785) non L. Type: n.v. Azalea arborescens Pursh, Fl. Am. Septentr. 152 (1814). Type: n.v. Azalea fragrans Raf., Ann. Nat. 12 (1820). Type: n.v. Rhododendron arborescens (Pursh) Torr. var. richardsonii Rehder, Monogr. Azaleas 168ó 169 (1921). Azalea arborescens Pursh var. richardsonii (Rehder) Ashe, J. Elisha Mitchell Sci. Soc. 38: 91 (1922). Type: North Carolina, Macon Co.: on Wayoh [sic] Bald, alt. 5200 ft, T G. Harbison 170 (holo. A).

Flags

Occurs in Countries: US Altitude Ranges: 0 - 1,000m: 1,000 - 2,000m Subgenus: Pentanthera Habit: Tree

Kron, K.A. (1993) A Revision of Rhododendron Section Pentanthera. Edinburgh Journal of Botany 50(3):287

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Rhododendron arboreum Smith

Usually a tree (l-)5-50m, with a well-defined trunk. Leaves narrowly to broadly elliptic or ovate, 6.5 — 19 x 1.8—5cm, 2.2-6.5 x as long as broad, upper surface reticulate to bullate, glabrous, lower surface with a dense compacted to spongy, white to fawn dendroid tomentum, occasionally also with a floccose rufous upper layer; petioles l-2cm, with a loose indumentum intermixed with glands, sometimes glabrescent at maturity. Inflorescence 10-20-flowered, dense; rhachis 15-20mm; pedicels 5-10mm, pilose and glandular. Calyx l-2mm, lobes rounded, sparsely glandular to ± glabrous. Corolla fleshy, ± tubular-campanulate, pink to deep crimson, rarely pure white, with dark flecks and nectar pouches, 30-50mm. Ovary white-tomentose, sometimes also glandular. Capsule 15-30 x c.6mm.

Notes

R. arboreum is an extremely variable species, especially with respect to leaf shape and leaf indumentum, with a wide geographical range and clear-cut geographical differentiation. This species reaches its greatest complexity in NE India and adjacent E Nepal and Bhutan where there is intergradation between subsp. arboreum and subsp. cinnamomeum, though the former predominates below 2500m and the latter above 2900m. Subsp. delavayi apparently intergrades with subsp. arboreum in NW Burma where a range of intermediates occurs. It is also sometimes difficult to distinguish some forms of subsp. delavayi from subsp. cinnamomeum, especially where the ranges of the two approach one another, as in SE Bhutan. The two isolated subspecies, subsp. zeylanicum and subsp. nilagiricum, are closer to one another than they are to subsp. delavayi, from which they are clearly divided.

Natural hybrids occur between var. roseum and three other species: R. barbatum, R. campanulatum and R. wallichii.

Flags

Occurs in Countries: BT, CN, IN, LK, MM, NP, TH Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Hymenanthes Habit: Tree Fl. Colour: carmine, crimson, pink, red, white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):328

Rhododendron arboreum subsp. arboreum

Leaves (8—)10—19 x (2.4-)3-5cm, 3-4(-5) x as long as broad, apex acute, upper surface reticulate, lower surface with a compacted, usually white to silvery indumentum. Corolla bright red to carmine, rarely pink or white.

Habitat: Usually in open or mixed forests

Distribution: N India(from Kashmir to Sikkim), Nepal, Bhutan

Altitude: 1850-3200m

Notes

Subsp. arboreum apparently merges with both subsp. cinnamomeum var. roseum and subsp. delavayi.

Nomenclature

Type: a plate accompanying the type description, drawn from plants seen near Srinagar (Kashmir) by Capt. Hardwicke in 1796.

Synonymy: R. puniceum Roxburgh, Fl. British India 2: 409 (1832). Type: N India, mountains N of Nohilkhund, Hardwicke, n.v. R. windsorii Nuttall, Hooker's J. Bot. Kew Gard. Misc. 5: 357 (1853). Type: Nepal, on the ridges and slopes of Ropprye, 7-9000ft, Nuttall (holo. K)

Rhododendron arboreum subsp. cinnamomeum (Lindley) Tagg

Rhododendron arboreum subsp. cinnamomeum [Wallich ex] Lindley

Leaves 6.5-11 x 2.5-6cm, 2.5-3.7 x as long as broad, apex acute, upper surface reticulate, lower surface with a bistrate indumentum, the upper layer loose and floccose, rufous, the lower whitish to fawn and compacted. Corolla pink to carmine, occasionally white.

Habitat: Open forests and rocky slopes

Distribution: E Nepal, NE India (Bengal & Sikkim)

Altitude: 2750-3650m

Nomenclature

Type: Nepal, 1821, Wallich 760, n.v.

Synonymy: R. cinnamomeum [Wallich ex] G. Don, Gen. Syst. 3: 844 (1834). Type: as above. R. campbelliae Hooker f., Rhododendrons Sikkim Himalaya t.6 (1849). Type: N India, Sikkim, 9-10000ft, Hooker, n.v. R. arboreum Smith subsp. campbelliae (Hooker f.) Tagg in Stevenson (ed.), The Species of Rhododendron 15 (1930).

Rhododendron arboreum subsp. cinnamomeum Lindley

Leaves 6.5-ll x 2.2-4.5cm, 2.7-3.5 x as long as broad, apex acute, upper surface reticulate, lower surface with a unistrate compacted, usually fawn or whitish indumentum. Corolla pink to carmine, rarely white.

Habitat: Open forests, rocky slopes

Distribution: E Nepal, NE India (Bengal, Sikkim, Arunachal Pradesh), Bhutan, China (CXizang)

Altitude: 2750-3650m

Notes

Var. roseum intergrades with both subsp. arboreum and subsp. delavayi.

Nomenclature

Type: the above plate drawn from a plant in 1828, cultivated by Mr Knight from seed sent from Nepal by Jenkinson.

Synonymy: R. arboreum Smith var. album Wallich, PL Asiat. Rar. 2:23, t.123 (1830). Type: Nepal, in monte Sheopore, 10000ft, Wallich, n.v, R. album Buchanan-Hamilton in Sweet, British Fl. Gard. ser. 2,2: t.148 (1832). Type: Nepal, Narainhatty, iii 1803, Buchanan-Hamilton, n.v.

Rhododendron arboreum subsp. delavayi (Franchet) Chamberlain

Rhododendron arboreum subsp. delavayi

Leaves 7—13.5(—15.5) x 2-2.4cm, 2.8-4.4 x as long as broad, apex acute, upper surface reticulate, lower surface with a unistrate spongy, whitish to fawn indumentum. Corolla usually deep crimson to carmine.

Habitat: Open forests, etc.

Distribution: NE India (Meghalaya, Manipur, Assam, Arunachal Pradesh), Burma, Thailand, China (Yunnan, Guizhou)

Altitude: 1500-3000m

Nomenclature

Synonymy: R. delavayi, Bull. Soc. Bot. France 33: 231 (1886). Type: China, Yunnan, in monte calcareo Houangli-pin, 2500m, Delavay 242 (iso. E, K). R. pilovittatum Balfour f. & W. W. Smith, Notes R.B.G. Edinb. 10: 134 (1917). Type: China, W Yunnan, on the Yung-peh Mountains, 9000ft, vi 1914, Forrest 12745 (holo. E; iso. K). Ic: Bot. Mag. 133: t.8137 (1907)

Rhododendron arboreum subsp. delavayi (Balfour f. & Forrest) Chamberlain

Leaves (7.5-)9-15(-18) x 1.8-3(-4.2)cm, 4.5-6.5 X as long as broad apex acute to shortly cuspidate, with a loose spongy, fawn indumentum below. Corolla usually crimson to carmine.

Distribution: NE India (Arunachal Pradesh), China (W Yunnan).

Notes

A specimen from C Xizang (Kingdon-Ward 19245), with narrow leaves but a compacted leaf indumentum, is probably referable to this variety.

Nomenclature

Synonymy: R. peramoenum Balfour f. & Forrest, Notes R.B.G. Edinb. 13: 56 (1920). Type: China, W Yunnan, Shweli/Salween divide, vi 1918, Forrest 17708 (holo. E; iso. K).

Rhododendron arboreum subsp. nilagiricum (Zenker) Tagg

Leaves 8.5-12 x 3.8-6cm, 1.8-2.4 x as long as broad, apex ± rounded, apiculate, upper surface rugose, lower surface with a spongy yellowish-brown indumentum. Corolla carmine.

Habitat: Upland forests

Distribution: S India (Tamil Nadu)

Altitude: Around 2250m

Illustrations:

  • Wight, Spicil. Neilagerr. 2: t.131 (1851)
Nomenclature

Synonymy: R. nilagiricum Zenker, Amer. Sci. Nat. ser. 2, 6: 150 (1836). Type: S India, Saladia, Nilgiri Hills, Utacamund, Schmidt (iso. E).

Rhododendron arboreum subsp. zeylanicum (Booth) Tagg

Leaves 8-11 x 3.5-4.5cm, 2.2-2.8 X as long as broad, apex blunt to acute, upper surface with strongly impressed veins, bullate, margin strongly recurved, lower surface with a spongy brownish indumentum. Corolla carmine.

Habitat: Upland regions

Distribution: SRI lanka

Altitude: Around 2300m

Illustrations:

  • Millais, Rhododendrons ed.l: 24, t. (1917)
Nomenclature

Synonymy: R. zeylanicum Booth, Gard. Chron. 150 (1850). Described from a plant cultivated in Sir Charles Lemon's garden in Cornwall

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Rhododendron archboldianum Sleumer

Tall shrub. Twigs rounded, thick, at first sub-densely scaly, later glabrescent; internodes 6–16cm. Leaves 5–7 together in pseudowhorls, in which 3–4 leaves are normal, the rest much smaller. Blade 40–110 x 20–60mm, ovate to elliptic-ovate, often asymmetrical; apex shortly acuminate, sub-acute; margin entire, sub-revolute proximally; base sub-truncate-rounded or broadly tapering, sometimes sub-cordate, sub-densely scaly on both sides, the scales slowly disappearing above, persistent for a long time beneath. Scales flat, small, the margin irregularly deeply dentate; centre not impressed. Mid-vein slightly depressed above, thickly prominent beneath proximally, less so distally; lateral veins 8–11 per side, slightly curved, irregular, anastomosing with each other before the margin, faintly impressed or raised above, raised beneath, reticulation dense, more visible beneath only. Petiole 4–12 x 1.5–2mm, grooved above, sub-densely scaly. Bracts to 10 x 7mm, ovate to broadly obovate, laxly scaly and with hairs outside. Bracteoles to 15mm, narrowly linear, glabrous or laxly scaly. Inflorescence an 8–15-flowered open umbel. Pedicels 8–11mm, densely scaly, obliquely thickened below the calyx. Calyx small, rim-like, wavy, indistinctly 5-lobed. Corolla trumpet-shaped, pink; tube 45–50 x c.2.5 x 3.5–4.5mm, cylindrical, slightly curved, gradually expanding from the base but then a little constricted below the mouth, laxly to sub-densely scaly outside, densely hairy inside almost to the mouth; lobes 10–12 x 8–12mm, broadly spathulate to nearly circu­lar, laxly scaly outside at the base and in the middle, glabrous inside. Stamens exserted; filaments linear below, filiform above, shortly hairy nearly to the top; anthers 3.5–4 x 1mm, oblong, base obtuse. Disc glabrous below, densely hairy on the upper margin. Ovary 7–8 x c.2mm, cylindrical, gradually tapering distally, densely appressed-hairy and obscurely scaly; style as long as the corolla tube, covered with sub-patent hairs and scales nearly to the top; stigma thick, shortly obconical.

Habitat: Usually epiphytic in ridge forests, occasionally terrestrial in clearings

Distribution: Papua New Guinea, Mts Tafa and Suckling.

Altitude: Around 2400m

Notes

Named after Richard Archbold and his daughter Anne, American philanthropists and explorers who financed the expedition on which this plant was collected.

Nomenclature

Type: Brass 4855, May–Sept. 1933. New Guinea (E), Central District, Mt Tafa (L, A, BO, NY).

Flags

Occurs in Countries: PG Altitude Ranges: 2,000 - 3,000m Subgenus: Vireya Habit: Epiphyte, Non-Tree Fl. Colour: pink

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:177

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Rhododendron arenicola Sleumer

Erect shrub to 2m. Twigs rounded, densely pale-brown-scaly; internodes 3–8cm. Leaves scattered in the upper ½ of the upper 1–2 internodes. Blade 20–40 x 15–26mm, elliptic, broadly elliptic or rarely sub-ovate-elliptic; apex obtuse to very shortly acuminate or apiculate, with a blunt terminal gland; margin minutely crenulate, not or only very slightly revolute; base sub-truncate to rounded; very densely reddish brown-scaly beneath at least initially the scales forming a continuous layer. Scales lobed or rounded with a broad marginal flange, centres variable, slightly impressed, becoming glabrescent and then densely pitted. Mid-vein flat above, slightly prominent beneath; lateral veins 5–7 per side, the lower 2–3 from, or from slightly above, the base, the remainder straight at first, curving distally and obscurely anastomosing, faintly impressed above, slightly raised beneath, somewhat rugose above when mature. Petiole 3–4 x 2–3mm, not grooved above, flattened, scaly. Flower buds broadly ovoid, c.15 x 10mm. Bracts to 15 x 10mm; outer bracts ovate, inner ones sub-spathulate, blunt, with white silky hairs and also scaly along the midline outside. Bracteoles to 3mm, slender. Inflorescence 7–13-flowered, in an open umbel, hanging, without scent. Pedicels 15–25 x c.1mm, densely brown-scaly but without hairs. Calyx disc-shaped, c.3.5mm in diameter, densely scaly outside, the margin wavy and spreading, indistinctly, bluntly 5-lobed. Corolla 23–27 x 20–27mm, tubular- campanulate, pink; tube 12–18 x 6–7 x 9–11mm, a little pouched at the base, laxly to sub-densely scaly outside and with a few simple hairs outside at the base and a few inside near the base only; lobes 12 x 11mm, broadly obovate to nearly rounded, retuse or irregularly crenulate, spreading almost to the perpendicular, overlapping to c.halfway. Stamens regularly arranged in a circle, just included or slightly exceeding the corolla tube in length, weakly dimorphic; fila­ments 1–3mm, white, filiform, glabrous or with some sparse hairs near the base; anthers 18 x 1.2mm, brown, oblong. Disc glabrous or with dense long hairs on the upper side. Ovary 4–5 x 3–4mm, green, thick, conical, abruptly contracted to the style, covered with patent or somewhat distally pointed white hairs which obscure dense silvery scales; style 4–6mm, thick, glabrous; stigma large, sub- conical, distinctly 5-lobed, centrally placed.

Habitat: On open sandy ridges

Distribution: Indonesia, SW Central Sulawesi, Latimodjong Range.

Altitude: 2600-3000m

Notes

Latin – arenicola – sand dwelling, alluding to the fact that it was first collected on a dry sandy ridge.

Introduced into cultivation by Galloway and Smith from Mt Rantemario where it was common at 2700m. It flowered for the first time in cultivation in Edinburgh in December 2003 with most attractive pale pink flowers. Plants in cultivation tend to be less scaly than those from the wild, with dense but not overlapping scales on the undersides of the leaves.

Nomenclature

Type: Eyma 955, 24 June 1937. Indonesia, Sulawesi, Enrekang, Batubóllong-Madjadja, NNW of Madjadja, 2900m (BO, L).

Flags

Occurs in Countries: ID Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Vireya Habit: Non-Tree Fl. Colour: pink, white

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:132

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Rhododendron arfakianum Becc.

Shrub to 2.5m. Twigs 2–3mm in diameter, sparsely scaly and papillose-hairy in the youngest parts, becoming glabrescent; internodes 2–10cm. Leaves 3–5 together in tight pseudowhorls. Blade 40–100 x 15–45mm, obovate-elliptic; apex obtusely tapering or nearly rounded; margin entire, slightly revolute in dry specimens; base tapering or broadly tapering, glabrescent above when mature, sub-persistently and sub-densely to laxly scaly beneath. Scales small, with the marginal zone irregularly lobed and a minute dark centre, slightly impressed, each scale surrounded by a dark halo, also very finely punctate by minute emergences of the epidermis beneath. Mid-vein slightly depressed and with minute, papillose, spreading hairs above, as wide as the petiole and obtusely prominent in the lower part beneath; lateral veins 6–10 per side, spreading, obscurely inarched at the margin, slightly prominent on both sides, reticulation inconspicuous. Petiole 6–12 x 1–1.5mm, with minute, papillose, spreading hairs above. Outer bracts to 15 x 8mm, ovate, obtuse, inner ones oblong-obovate, laxly scaly and minutely hairy outside, becoming glabrescent, fringed with scales. Bracteoles to 23 x 0.5–4mm, filiform below, spathulate distally, papillose. Inflorescence a 4–10-flowered umbel. Pedicels 8–12mm, slender, laxly to sub-densely scaly and finely patently hairy. Calyx c.3mm in diameter, disc-shaped, membranous, sub-obtusely and very shortly unequally lobed, wavy, spreading to reflexed, glabrous outside, distinctly ciliate. Corolla 25–35mm, tubular below, expanded upwards, oblique, deep pink; tube 15–20 x 3–4 x c.5mm, sub-cylindrical, straight or slightly curved, glabrous outside, laxly hairy inside; lobes 7–10 x 5–8mm, sub-erect, or somewhat spreading, obovate-spathulate. Stamens spreading all round the mouth, unequal, the longest as long as the corolla; filaments linear and laxly hairy below, filiform and glabrous distally; anthers 2mm, obovate. Disc shortly hairy. Ovary c.4 x 2mm, sub-cylindrical, densely short-hairy and minutely scaly (the scales covered by hairs), abruptly contracted distally; style slender, sometimes with some hairs at the very base, equalling the stamens in length; stigma club-shaped, obconical, oblique. Fruit (sub-mature) 20 x 4mm, fusiform, densely hairy, surmounted by the glabrous, 20mm style.

Habitat: At the edge of forest,locally common, epiphytic or more rarely terrestrial.

Distribution: Indonesia, New Guinea (W), Arfak and Nettoti Mts.

Altitude: 1200-2135m

Notes

Named after the mountains from where this species was described.

Said to be close to R. angiense J.J.Sm. but differing in the shortly hairy pedicels and non-scaly corolla. Introduced into cultivation from seed sent by Professor Sleumer to the Australian Rhododendron Society in 1962. Doubtfully still in cultivation.

Nomenclature

Type: Beccari 5792. New Guinea, W Arfak Mts, Hatam (FI).

Synonymy: R. undulaticalyx J.J.Sm. in Gibbs, Phyto. Fl. Arfak Mts. 1917. 168.

Flags

Occurs in Countries: ID Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Vireya Habit: Epiphyte, Non-Tree Fl. Colour: pink

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:309

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Rhododendron argyrophyllum Franchet

Shrub or small tree, 2-12m. Leaves elliptic to oblanceolate, 6-16 x 1.8-6cm, 2.7—3.6 x as long as broad, apex acute to acuminate, upper surface glabrous, lower surface with a thing silvery to fawn compacted indumentum embedded in a surface film; petioles 1 -2cm, floccose at first, soon glabrescent. Inflorescence lax, 4-10-flowered; rhachis 10-15mm; pedicels 20-25mm, floccose, sometimes also glandular. Calyx c.2mm, floccose, lobes broadly triangular, sometimes glandular-ciliate. Corolla funnel-campanulate to open-campanulate, white to pale pink, with purple flecks, 30-55mm. Ovary with a thin white floccose to rufous-glandular indumentum; style glabrous. Capsule 10-25 x 3-4mm, narrowly cylindrical, curved.

Habitat: Bamboo thickets, forests, open slopes

Altitude: 1600-3650m

Notes

A very variable species with some geographical variation. Closely allied to R. pingianum (q.v.).

Flags

Occurs in Countries: CN Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Hymenanthes Habit: Tree Fl. Colour: pink, purple, white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):325

Rhododendron argyrophyllum subsp. argyrophyllum

Leaves 6-9(-1 l)cm; corolla 30-35mm. Leaf indumentum white to silvery; ovary eglandular or glandular. Ovary and pedicels eglandular.

Distribution: China (Yunnan, Sichuan, Shaanxi)

Illustrations:

  • PI. Omeiens. t.19 (1942)
Notes

The corolla varies from open-campanulate (var. cupulare) to funnel-campanulate (R. argyrophyllum sensu stricto). This character, however, is lost in the herbarium and there is in any case considerable overlap.

Nomenclature

Type: China, W Sichuan, circa Moupine, 3000m, Abbe David (iso. E).

Synonymy: R. chionophyllum Diels, Bot. Jahrb. 29: 512 (1900). Syntypes: China, Sichuan, Nan chuan, Bock von Rosthorn 2157, 2161, n.v. R. argyrophyllum Franchet var. cupulare Rehder & Wilson in Sargent, (ed.), PL Wilsonianae 1: 526 (1913). Type: China, W Sichuan, Mupin, 2000-3000m, vi 1905, Wilson 3442 (iso. E,K).

Rhododendron argyrophyllum subsp. hypoglaucum (Hemsley) Chamberlain

Leaves 6-9(-1 l)cm; corolla 30-35mm. Leaf indumentum white to silvery; ovary eglandular or glandular. Ovary and pedicels glandular.

Distribution: China (E Sichuan, W Hubei)

Illustrations:

  • Stevenson (ed.), The Species of Rhododendron 30 (1930)
Nomenclature

Synonymy: R. hypoglaucum Hemsley, J. Linn. Soc. Bot. 26: 25 (1889). Type: China, Hubei, Patung district, Henry 723 (holo. K). R. gracilipes Franchet, J. Bot. (Morot) 9: 391 (1895). Type: China, E Sichuan, environs de Tchen-keou-tin, Farges 52 (iso. E, K).

Rhododendron argyrophyllum subsp. nankingense (Cowan) Chamberlain

Nomenclature

Synonymy: R. argyrophyllum Franchet var. nankingense Cowan, Notes R.B.G. Edinb. 21: 148 (1953). Type: China, Guizhou, Lao Shan, 1250m, i 1931, Steward et al. 499 (holo. E); also in cultivation at Edinburgh as 'F46 flowered 7 v 1946(E). R. argyrophyllum Franchet var. leiandrum Hutchinson, Bot. Mag. 144: t.8767 (1918). Type: a plant cultivated at Kew from seed collected in 1908 in W Sichuan as Wilson 1353, n.v.

Rhododendron argyrophyllum subsp. omeiense (Rehder & Wilson) Chamberlain

Leaves 6-9(-1 l)cm; corolla 30-35mm. Leaf indumentum fawn; ovary eglandular.

Distribution: China (W Sichuan, Mt Omei)

Notes

Close to subsp. argyrophyllum and possibly only a local variant.

Nomenclature

Synonymy: R. argyrophyllum Franchet var. omeiense Rehder & Wilson in Sargent (ed.), PI. Wilsonianae 1: 527 (1913). Type: China, W Sichuan, v 1904, Wilson 3962 (holo. A; iso. K).

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Rhododendron armitii F.M.Bailey

Shrub to 2.5m. Twigs rounded, tips sparsely to sub-densely stellately scaly; internodes 2–12cm. Leaves 4–5 in well-marked pseudowhorls. Blade 70–100 x 30–60mm, elliptic, broadly elliptic, to sub-obovate-elliptic; apex very shortly obtuse; margin entire, flat or slightly revolute; base rounded or broadly tapering, the extreme base sometimes truncate to slightly sub-cordate; sub-densely scaly on both sides initially, early glabrescent above, more persistently scaly beneath. Scales thin, flat, brown, often on minute low epidermal elevations which are still visible as pale spots when the scales have gone, marginal zone thin, irregularly deeply incised; centre very small. Mid-vein impressed above, very prominent beneath especially proximally; lateral veins 8–10 per side, straight basally, sometimes forking, obscurely curved-anastomosing before the margin, smooth above when fresh, (raised when dry), prominent beneath, laxly reticulate, more visible beneath, veinlets obscure. Petiole 8–15 x 2.5mm, grooved above, semi-rounded, brown-scaly. Flower buds to 30 x 12mm, narrowly ovate, acutely pointed, green, the bract tips spreading and recurving, densely hairy and with a few scales outside and fringing the bract margins. Bracts ovate to obovate-spathulate. Bracteoles c.20 x 2.5mm, linear-spathulate, laxly hairy. Inflorescence an open one-sided umbel of 5–7 flowers, held horizontally or half-hanging. Pedicels 15–25 x c.2mm, sub-densely scaly, sometimes with a few hairs below the calyx, red. Calyx distinct, scaly and laxly hairy outside, glabrous inside, irregularly, deeply 5-lobed, lobes triangular, c.3 x 2mm, occasionally subulate up to 7mm, red, fringed often becoming reflexed. Corolla 55–60 x 35–40mm, trumpet-shaped, white or pink with white lobes; tube 45–60 x 5–6 x 10–12mm, straight or slightly curved, angled in section and grooved proximally, very laxly scaly or practically glabrous outside, densely long-hairy inside in the proximal 1⁄3, becoming less densely so and glabrous in the distal 1⁄3; lobes c.15–20 x 14–18mm, broadly obovate to nearly circular, spreading, overlapping to c.halfway, glabrous. Stamens loosely clustered on the lower side of the mouth, exserted to c.6mm, hanging down on the lower side in older flowers; filaments slender, white, densely hairy at the base, becoming less so, and completely glabrous in the distal 1⁄3; anthers 3–4 x c.1mm, oblong, base obtuse. Disc glabrous or hairy. Ovary 10–12 x 2.5–3mm, elongate-conical, 5-ribbed, densely covered with appressed white hairs, which cover some scales, gradually tapering distally; style densely hairy and very laxly scaly in the proximal ½, glabrous and more slender distally; stigma broadly obconical, distinctly 5-lobed, becoming exserted to 12mm.

Distribution: Papua New Guinea, Mt Dayman, summit; Central/Northern District, Mt Suckling; Milne Bay District, Mt Vineuo, Goodenough Is.

Altitude: 2250-2710m

Notes

Named after the collector William Edington de Margrat Armit, Belgian officer of the Queensland mounted police, who led the Argus expedition to Papua on which this species was collected.

Nomenclature

Type: Armit, 1894. New Guinea, Milne Bay District, Mt Dayman, 2710m (BRI, MEL).

Flags

Occurs in Countries: PG Altitude Ranges: 2,000 - 3,000m Subgenus: Vireya Habit: Non-Tree Fl. Colour: pink, white

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:178

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Rhododendron arunachalense Chamberlain & Rae

Shrub, 4.5m; young shoots adpressed-brown-strigose. Leaves probably dimorphic, chartaceous; spring leaves elliptic-ovate lanceolate, 3.5-6.5 x 1.6-2.8cm, c.2.3 x as long as broad, apex acuminate, base cuneate, margin with stiff incurved hairs, ± entire, upper surface sparsely adpressed-strigose, lower surface adpressed rufous-strigose, densely so on midrib and lateral veins; petioles 6-12mm, densely adpressed strigose. Inflorescence 3-flowered; pedicels 5-7mm, densely brown-strigose with large stiff and thinner crisped hairs. Calyx ± obsolete, strigose. Corolla open funnel-shaped, light pink, darker inside, 23-27mm; tube 6-7mm, glabrous, 3mm broad at base, 6mm broad above. Stamens 5, 30mm long, scabrid at base. Ovary densely strigose; style glabrous 35mm. Capsule unknown.

Habitat: River beds

Distribution: N E India (Arunachal Pradesh)

Altitude: Around 1500m

Notes

This new species is geographically isolated, and is the most westerly of the subgenus.

Probably allied to R. saxicolum but with a more acute leaf, corolla darker, tube glabrous within.

Nomenclature

Type: N E India, Arunachal Pradesh, Subansiri district, Yachuli, 1500m, 28 iv 1977, H.B. Naithani Ser.II:894 (holo. E, iso. DD)

Flags

Occurs in Countries: IN Altitude Ranges: 1,000 - 2,000m Subgenus: Tsutsusi Habit: Non-Tree Fl. Colour: pink

Chamberlain, D.F. & Rae, S.J. (1990) A Revision of Rhododendron IV Subgenus Tsutsusi. Edinburgh Journal of Botany 47(2):131

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Rhododendron asperrimum Sleumer

Epiphytic, spreading shrub. Twigs c.2mm in diameter, slender, initially covered with reddish, dendroid scales; internodes 3–7cm. Leaves 3–4 together in pseudowhorls at the upper 2–3 nodes, sub-sessile. Blade 25–45 x 15–30mm, ovate; apex very broadly tapering to rounded; margin revolute distally; base a little cordate; sub-densely scaly above, quickly glabrescent but rough with the persistent epidermal scale bases, densely scaly and more persistently scaly beneath, eventually glabrescent here also but remaining rough with epidermal tubercles. Scales reddish-brown, stellate-dendroid, the tubercles often very pale in colour after the scales have fallen. Mid-vein impressed above, prominent beneath; lateral veins inconspicuous on both sides, without reticulation. Petiole 2 x 1.5mm, scaly. Bracts to 15 x 7mm, thin, ovate to spathulate, sparsely scaly at first becoming glabrous. Bracteoles c.10mm, linear to filiform, glabrous. Inflorescence 3–6-flowered. Pedicels 11–15mm, slender, very densely stellate-scaly, not hairy. Calyx 2–3mm in diameter, obliquely rimmed, shortly or hardly 5-lobed, densely scaly outside. Corolla 26–30mm, tubular, zygomorphic, pink to purplish; tube c.20 x 4–5 x 6–7mm, curved, initially, densely, later more sparsely scaly, often finally glabrescent outside, laxly papillose-hairy inside; lobes c.10 x 6mm, unequal, spreading, obovate-spathulate. Stamens almost equalling the corolla in length; filaments linear, laxly papillose-hairy in the proximal ½, glabrous distally; anthers 2 x 1.3mm, obovate-elliptic, the base obtuse. Disc glabrous below, hairy on the upper margin. Ovary c.4 x 1.5mm, sub-cylindrical, densely covered with reddish-brown, stellate scales and more sparsely with paler hairs, abruptly contracted distally; style scaly at the base, and sometimes sparsely patently hairy in the proximal ¼, otherwise glabrous; stigma sub-globose.

Habitat: Primary forest

Distribution: Indonesia, New Guinea (W), Wandamen Peninsula, Wondiwoi Mts.

Altitude: 800-1800m

Notes

Latin – asper – rough or uneven; erimum – the superlative ending, very rough. Alluding to the large persistent epidermal tubercles on the leaves.

Nomenclature

Type: Koster 13744, March 1962. New Guinea, Wandamen Peninsula, Wondiwoi Mts, 1800m (A, CANB, K, L).

Flags

Occurs in Countries: ID Altitude Ranges: 0 - 1,000m: 1,000 - 2,000m Subgenus: Vireya Habit: Non-Tree Fl. Colour: pink

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:74

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Rhododendron asperulum Hutch. & Kingdon-Ward

Small shrub. Twigs reddish, densely covered with rounded scales on stalks later rough with the persistent scale stalks and when dry, the surface minutely rugose. Leaves in loose to moderately compact pseudowhorls of 4–8 together. Blade 16–22 x 7–10mm, broadly spathulate to elliptic; apex rounded to slightly emarginate with a shortly protruding, mucronate gland; margin recurved especially proximally; base tapering or narrowly tapering, somewhat decurrent; upper surface sparsely scaly, the scales not impressed and the surface becoming glabrescent; below moderately to sparsely and persistently scaly. Scales round and impressed with broad swollen centres and narrow flanges. Mid-vein impressed above and raised below throughout its length; lateral veins 1–2 per side, narrowly impressed above, and weakly raised below, in smaller leaves totally obscure. Petiole 1.5–2 x c.1mm, scaly. Outer bracts subulate, scaly outside, fringed with hairs and with a few hairs inside near the apex, inner bracts ovate scaly outside, fringed with short hairs, glabrous inside. Bracteoles sub-linear, becoming broader distally, fringed with hairs, the truncate apices especially fringed with long white hairs. Inflorescence 3-flowered. Pedicels 10–20 x c.1mm, densely to sparsely scaly. Calyx 2.5–3 x 1.5–2mm, lobes broadly elliptic, scaly outside and with scales on the margin whose stalks give the lobes an irregular edge. Corolla c.7 x 5mm, pale pink; tube c.5 x 4 x 5mm, densely scaly outside, glabrous inside; lobes c.3 x 2.5mm, with a few scales outside in the basal ½. Stamens exserted, with long hairs in the middle part of the filaments; anthers 1.5mm, orange in colour. Ovary c.3 x 1.75mm, densely scaly but without simple hairs; style c.3mm, glabrous. Fruit c.25mm. Seeds small with tails.

Habitat: Epiphytic on alders and other trees in open pastures. On boulders in the valley of the Di Chu (Kingdon-Ward 7163).

Distribution: Myanmar, (Upper), Base Camp, Seinghku Wang, 28°5'N 97°30'E.

Altitude: 1900-2100m

Notes

Latin – asper – rough – the diminutive form – slightly or minutely rough, referring to the stems.

A very imperfectly known species very similar to R. vaccinioides, differing chiefly in the pseudowhorled arrangement of the leaves. The isotype in Edinburgh is mixed with R. insculptum, and the paratype 7163 (also in Edinburgh) shows some variation in that it has faint pinnate venation which is not evident in the type, but this specimen is without flowers. This species apparently grows with R. insculptum but besides having differently coloured flowers is said to flower about one month later. It also differs in the smaller leaves without the very distinct lateral veins of R. insculptum and lacks simple hairs on the ovary.

Nomenclature

Type: Ward 6801, 30 May 1926. Upper Burma, Seinghku Wang (K, E).

Flags

Occurs in Countries: MM Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Vireya Habit: Epiphyte, Non-Tree

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:30

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Rhododendron asperum J.J.Sm.

Shrub to 2m. Twigs 2–4mm in diameter, thick, densely stellate-scaly, rounded, densely warty and rough to the touch; internodes 3–10cm. Leaves 5–10 together in pseudowhorls. Blade 25–60 x 15–50mm, ovate, elliptic or sub-circular, sometimes obovate-elliptic, sub-sessile; apex obtuse to rounded; margin distinctly recurved in dry specimens; base broadly rounded or mostly shortly cord­ate; densely stellate-scaly on both sides at first, quickly glabrescent above, the scales more persistent beneath, rough with the numerous minute tubercles on both sides especially beneath. Scales small, deeply divided, sub-­sessile each on top of a small persistent elevated pale tubercle. Mid-vein a little impressed above, strongly obtusely prominent in its basal ½ beneath, gradually less so distally; lateral veins 5–9 per side, inconspicuous, spreading irregularly, faintly anastomosing before the margin, very slightly impressed in fully mature leaves above, somewhat prominent beneath, rigid, greyish green to dark green above, brown below. Petioles 1–2.5 x 1–2mm, somewhat flattened. Bracts to 20 x 10mm, membranous, outer ones smaller, ovate to sub-circular, shortly subulate-acuminate, scaly and shortly hairy outside at the apex; inner ones larger, obovate to spathulate, glabrous. Bracteoles to 20 x 1mm, linear, laxly hairy or nearly glabrous. Inflorescence a 5–9-flowered umbel. Pedicels 15–30 x c.1mm, red, densely stellate-scaly. Calyx c.4mm in diameter, oblique, in the form of a shallow cup, densely scaly outside, very shortly and obtusely 5-lobed. Corolla 35–45 x 35–45mm, regular, white or to deep pink, sometimes with the tube of a more intense colour than the lobes, scented; tube 20–28 x 4 x 10mm, funnel-shaped, laxly scaly outside and sparsely hairy inside; lobes 15–19 x 15–19mm, spreading perpendicularly, sub-circular with some scales at the base outside, glabrous otherwise. Stamens somewhat exserted from the throat; filaments linear, sparsely hairy in the proximal ½–2⁄3, glabrous distally; anthers 3–4 x 1mm, oblong. Disc low, hairy at the upper margin only. Ovary conical-cylindrical, densely covered with white spreading hairs and stellate scales which are often hidden between and below the hairs, gradually tapering distally; style 20–23mm, slender and covered with spreading hairs and some scales in the lower ½–2⁄3, glabrous distally; stigma globose. Fruit 15–18 x 6–8mm, sub-cylindrical, densely brown-stellate-scaly and hairy.

Habitat: Terrestrial in heath-forest on ridges at the edge of degraded Nothofagus forest, or on the burnt open summit areas, on poor clayey soil, granite and quartzite

Distribution: Indonesia, New Guinea (W), Arfak Mts.

Altitude: 2150-2750m

Notes

Latin – asper – rough, alluding to the leaves which are rough due to the persistent epidermal tubercles.

Sleumer (1966) described wild hybrids of this species with R. laetum. These hybrids were characterised by glossy, shortly acuminate leaves, less distinct epidermal tubercles, the bracts densely hairy outside and c.2.5cm long. The pedicels were also scaly and hairy, the anthers c.4mm long, the ovary densely hairy and the corolla varying from pale greenish-yellow to pink and then often with yellow or greenish colour in the lower part of the tube.

Nomenclature

Type: Gjellerup 1203, 30 April 1912. New Guinea, Arfak Mts, Angi Lakes (lectotype, BO, L).

Flags

Occurs in Countries: ID Altitude Ranges: 2,000 - 3,000m Subgenus: Vireya Habit: Non-Tree Fl. Colour: pink, white

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:74

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Rhododendron asterochnoum Diels

Small tree. Leaves oblanceolate, 18-20 x 5-6 cm, c.3.5 x as long as broad, apex rounded, base cuneate, lower surface with a sparse discontinuous whitish stellate indumentum; petioles 1.5-2.5 cm, floccose. Inflorescence 15-20-flowered; rhachis 20-25 mm; pedicels 35-50 mm, glabrous or with a few hairs. Calyx c. 2 mm. Corolla 5-lobed, funnel-campanulate, white tinged with rose, apparently with a basal blotch, c. 45 mm. Stamens c. 20, puberulent at base. Ovary and style glabrous; stigma discoid.

Distribution: China (C Sichuan)

Notes

Most probably allied to R. calophytum with which it shares the discoid stigma and large number of stamens but from which it differs in its stellate leaf indumentum, a unique feature in subsection Fortunea.

Nomenclature

Type: China, Sichuan, Wen tchuan hsien, in valle Scha pa, 3500-4000 m, 27 iv 1914, Limpricht (iso. K)

Flags

Occurs in Countries: CN Subgenus: Hymenanthes Habit: Tree Fl. Colour: rose, white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):229

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Rhododendron atlanticum (Ashe) Rehder

Shrub or small tree usually less than l(-3)m tall, very strongly rhizomatous; young twigs red-brown, rarely yellow-brown, sparsely to densely covered with multicellular eglandular hairs or with multicellular gland-tipped hairs, occasionally also with unicellular hairs, rarely with unicellular and multicellular eglandular and gland-tipped hairs. Vegetative bud scales sparsely to densely covered with unicellular hairs or glabrous abaxially; margin unicellular-ciliate, occasionally ciliate and glandular, rarely completely glandular. Leaf blade membranaceous, ovate or obovate to elliptic, (3.2-)3.4-4.7(-5.2) x (0.8-) 1.1-1.9(-2.0)cm; base acute to oblique; apex acute to obtuse, often mucronate; adaxial surface glabrous, occasionally sparsely covered with unicellular and multicellular gland-tipped hairs, or with only multicellular gland-tipped hairs, rarely densely covered with only unicellular hairs, the midvein densely covered with unicellular hairs; abaxial surface glabrous, often paler than the adaxial surface, rarely also glaucous, occasionally with scattered multicellular gland-tipped hairs, rarely with scattered multicellular gland-tipped hairs and unicellular hairs or scattered multicellular eglandular hairs, or densely covered with unicellular hairs, the midvein with multicellular eglandular or gland-tipped hairs, occasionally also with unicellular hairs, rarely with multicellular eglandular and gland-tipped hairs; margin entire, ciliate with multicellular eglandular hairs; petiole 0. l-0.4(-0.5)cm long, sparsely to densely covered with unicellular hairs and multicellular eglandular hairs, or with unicellular hairs and multicellular gland-tipped hairs, or with only multicellular eglandular and gland-tipped hairs, rarely with all three types of hairs. Flower bud scales chestnut brown; abaxial surface sparsely to densely covered with unicellular hairs, frequently glabrous; margin unicellular-ciliate, rarely unicellular above and glandular below. Flowers appearing before or with the leaves; inflorescence a shortened raceme of 4 to 13 flowers. Pedicels (0.4-)0.7-1.4(-2.0)cm long, sparsely to densely covered with unicellular hairs and multicellular gland-tipped hairs, or only with multicellular gland-tipped hairs, rarely with multicellular eglandular and gland-tipped hairs or with unicellular and multicellular eglandular hairs. Sepals less than 0.1-0.3(-1.0)cm long, often varying in length on die same flower; margins glandular-fimbriate, occasionally setose or with both gland-tipped and eglandular multicellular hairs; abaxial surface sparsely to densely covered with unicellular and multicellular gland-tipped hairs or with only multicellular gland-tipped hairs, occasionally with unicellular and multicellular eglandular hairs, rarely with all three types of hairs or glabrous. Corolla white, or white and tinged with pink or lilac, occasionally yellowish, fragrance sweet, musky and heavy, the tube longer than the limb and gradually expanding into It; upper corolla lobe (0.8-)1.0-L8(-2.2) x (0.6-)0.7-1.2(-1.6)cm; lateral lobes (L0-)1.2-2.0(-2.4) x (0.4-)0.5-0.9(-1.3)cm; corolla tube (1.6-)1.9-2.6(-3.1)cm long, (0.1-)0.2-0.4(-0.5)cm wide at base; outer surface of corolla densely covered with unicellular and multicellular gland-tipped hairs, the gland-tipped hairs continuing in distinct Enes up the corolla lobes, occasionally lacking unicellular hairs; inner surface of corolla sparsely to densely covered with unicellular hairs or glabrous. Stamens (3.2-)4.1-5.4(-6.3)cm long, with dense terete or flattened unicellular hairs on proximal (1.8-)2.4-3.3(-3.8)cm of filament, exserted (3.0-)4.2-5.1(-6.3)cm long, exserted (1.7-)2.4-3.8(-4.3)cm beyond throat of corolla, with dense unicellular hairs on proximal (0.3-)0.6-1.7(-2.6)cm; stigma 0.1-0.2(-0.3)cm wide. Ovary 0.2-0.4(-0.6)cm long, 0. l-0.2(-0.3)cm wide at the base, sparsely to densely covered with multicellular gland-tipped hairs and unicellular hairs, occasionally with multicellular eglandular hairs and unicellular hairs, or eglandular, gland-tipped hairs, unicellular hairs, rarely with only multicellular gland-tipped hairs. Capsules (1.0-)1.2-1.8(-2.4) x 0.4-0.6(-0.8)cm, ovate to narrowly ovate, sparsely covered with unicellular hairs and moderately to densely covered with multicellular gland-tipped hairs, often glaucous. Seeds pale to dark chestnut brown, ovate or elliptic to fusiform, (L2-)1.9-3.4(-3.5)x(0.6-1.0) expanded and dorsiventrally flattened surrounding the body, the cells elongate over the body of the seed, becoming shorter in the expanded portion of the testa, with transverse end-walls (Fig. 9).

Habitat: Sandy pinelands, swamps, shrub bogs, or along streams. Femald (1942) cites this species as 'thoroughly distinctive'of the Coastal Plain.

Distribution: Delaware to south-eastern Georgia along the Atlantic Coastal Plain

Altitude: 0-150m

Illustrations:

Notes

Chromosome number: 2n = 26 (Janakl-Ammal et al., 1950; Li, 1957)

Flowering primarily in April and May; however, this species may flower as early as March and Intermittently flower as late as November In the southern part of its range.

The relationship of Rhododendron atlanticum to the other white-flowered unblotched species, R. viscosum and R. arborescens, is not resolvable at present (see Phylogenetic Analysis). It Is distinct from both of these species by its flowering before or as the leaves expand. While!?, atlanticum Is isolated geographically from R. arborescens, it Is entirely sympatric with R. viscosum and is very similar to it morphologically. Rhododendron atlanticum Is quite variable In pubescence, flower colour and leaf size. Generally, however, It is more glabrous than R. viscosum, and has smaller leaves, which usually differ In length-to-width ratio from those of R. viscosum. In Virginia the leaves of R. atlanticum tend to be larger than the leaves of individuals throughout the rest of the species9 geographic range. Flower colour in R. atlanticum varies from white to pink (Weatherby & Griscom, 1934; personal observation) to white with a yellowish tinge (Femald, 1941). These forms have been formally recognized by Femald (1941) and by Ashe (1921) and Coker (1920), but in this treatment are not recognized because variation in corolla colour shows no correlation with other morphological characters or geographical distribution. Usually R. atlanticum is a low-growing, strongly rhizomatous species that has less well-developed branching than R. viscosum (which often can also be rhizomatous). However, sterile specimens of rhizomatous R. atlanticum and of glabrous, rhizomatous forms of R. viscosum can be nearly indistinguishable because of the natural variation within populations of R. atlanticum and R. viscosum.

Nomenclature

Synonymy: Azalea atlantica Ashe, Bull.Charles.Mus.l3:26(1917).TyPe:SouthCaroUna, Georgetown Co ï moist pine woods, Kinlock, 1 v 1916, W. W. Ashe s.n. (lecto., designated here, GH). Azalea atlantica Ashe var. luteo-alba Coker, J. Elisha Mitchell Sci. Soc. 36: 98, pi. 1 (1920). Rhododendron atlanticum (Ashe) Rehder var. luteo-album (Coker) Rehder, Monogr. Azaleas 150 (1921). R. atlanticum (Ashe) Rehder f. luteo-album (Coker) Fern. Rhodora 43: 622. (1941).Type: South Carolina, Darlington Co.: flatwoods, Hartsville, 4 iv 1918, /. L. Coker, Jr s.n. (lecto., designated here, NCU). Azalea neglecta Ashe, Bull. Torrey Bot. Club 47: 581 (1920). Rhododendron neglectum (Ashe) Ashe, Rhodora 23: 179 (1921). R. atlanticum (Ashe) Rehder f. neglectum (Ashe) Rehder, Monogr. Azaleas, 149-150 (1921). Type: South Carolina, Darlington Co.: moist pine woods, Kinlock, Georgetown, 1 v 1916, W. W. Ashe s.n. (holo. GH). Rhododendron atlanticum (Ashe) Rehder f. confusumVzm., Rhodora43: 622 (1941). Type: Virginia, Princess Anne Co.: dry oak thicket, Virginia Beach, 4 v 1935, Fernald & Griscom 4479 (holo. GH). Rhododendron atlanticum (Ashe) Rehder f. tom6>/o&wmFern.,Rhodora43:622 (1941). Type: Virginia, Nansemond Co.: a considerable colony, 6-9dm high, in dry white sand of pineland, south west of Marsh Hill School, south of South Quay, 10 v 1940, Fernald & Long 11881 (holo. GH; iso. GH, NY, PH).

Flags

Altitude Ranges: 0 - 1,000m Subgenus: Pentanthera Habit: Tree Fl. Colour: lilac, pink, white, yellow

Kron, K.A. (1993) A Revision of Rhododendron Section Pentanthera. Edinburgh Journal of Botany 50(3):290

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Rhododendron atropurpureum Sleumer

Erect shrub to 3m. Twigs c.2.4mm in diameter, densely covered with sub-stellate, shortly stalked brownish scales and very short papillose hairs at the upper internodes, older parts glabrescent and minutely warty; internodes 3.5–9cm often with prominent sub-spherical lateral buds in the upper leaf axils. Leaves spirally arranged in the upper 2⁄3 of the internodes. Blade 17–38 x 12–25mm, broadly elliptic or ovate-elliptic, sometimes sub-obovate-elliptic; apex broadly tapering, sub-acuminate or obtuse to rounded, the thick apical gland prominent; margin indistinctly cartilaginous and distinctly crenulate, flat; base rounded or slightly cordate, fully mature leaves with the remains of the scales persisting, a little rough, finally glabrescent above, sub-densely scaly beneath. Scales small, membranous, marginal zone irregularly crenate or denticulate, quickly disappearing to leave persistent large, blackish-red, impressed, circular centres. Mid-vein reddish-brown and more densely and persistently scaly than the rest of the upper surface, slightly impressed above, robust and obtusely prominent beneath; lateral veins 3–5 per side, spreading, faintly impressed above, slightly raised beneath, often inconspicuous above or rarely so on both sides. Petiole 4–5 x 1–1.5mm, flattened, densely scaly. Bracts 10–15 x 8–12mm, outer bracts ovate, bluntly pointed, the inner ones obovate, glabrous, but scaly on the margins. Inflorescence an open umbel of 2–3 flowers, half-hanging to hanging. Pedicels 10–15 x c.1mm, densely covered with dark, reddish, stellate, shortly stalked scales, but without hairs. Calyx 3–4mm in diameter, a low disc, shortly obtusely 5-lobed, densely scaly outside. Corolla 35–45 x 25–30mm, bright red when fresh, becoming dark purple in the drying process, without scent; tube 25–35 x 6–8 x 10–15mm, straight or distinctly curved, with 5 small pouches at the base, densely covered with thick sub-stellate scales outside, glabrous inside; lobes 10–15 x 10–13mm, spreading, broadly obovate or sub-circular, slightly retuse, scaly outside except towards the margins. Stamens exserted to 10–15mm, clustered on the upper side of the flower; filaments linear, 1.5mm wide at the base, glabrous; anthers 3.5–4 x c.1.5mm, broadly ellipsoid, each cell bearing a short basal apiculus. Disc prominent, glabrous. Ovary 5–6 x c.3mm, ovoid-conical, gradually tapering distally, densely sub-stellately scaly but without simple hairs; style nearly equalling the stamens in length, sub-densely to sparsely scaly in the proximal 1⁄3, glabrous distally; stigma rounded. Fruit 20–25 x 6mm, fusiform-cylindrical, shortly tapering at the base, more gradually so towards the apex, a little oblique, remaining densely scaly. Seeds 20–25mm, without tails c.10mm, the longest tail to 8mm, often with a broad tail at one end and a much more slender finely pointed one at the other.

Habitat: Common on the edge of sub-alpine forest or alpine shrubbery

Distribution: Papua New Guinea, Eastern Highlands, Mt Wilhelm; Western Highlands, Mt Kinkain.

Altitude: 3590-3840m

Notes

Latin – atro – blackish or very dark; purpureus – purple. The plant with dark blackish-purple flowers, but not apt (see below).

A hybrid with R. commonae has been recorded from Mt Wilhelm and hybrids with R. womersleyi are also found, having smaller leaves and hairs at the base of the style.

Nomenclature

Type: Womersley NGF 8870, 1 Aug. 1956. Papua New Guinea, Mt Wilhelm, Lake Piunde vicinity, 3620m (L, BM, BRI, CANB, K, LAE, SING).

Flags

Occurs in Countries: PG Altitude Ranges: 3,000 - 4,000m Subgenus: Vireya Habit: Non-Tree Fl. Colour: purple, red

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:227

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Rhododendron atrovirens Franchet

Large shrub or small tree; young shoots covered with adpressed flattened brown hairs. Leaves monomorphic, persistent, elliptic, 2-8 x l-3cm, 2-2.7 x as long as broad, apex acuminate, margin entire, base broadly cuneate to + rounded; both surfaces covered with adpressed shining brown hairs, glabrescent above except on midrib, lower surface paler, persistently adpressed brown-hairy, densely so on midrib and veins; petioles 5-8mm, strigose. Inflorescence 2-4-flowered; pedicels 6mm, densely covered with adpressed flattened shining brown hairs. Calyx 2~4mm, indumentum as for pedicels, lobes short, deltoid. Corolla funnel-campanulate, glabrous, red with darker flecks at base of upper lobes, 15-30mm; tube 7-10mm, glabrous, 4mm wide at base. Stamens 10, unequal, to c.30mm, shortly pilose below middle. Ovary densely covered with adpressed flattened shining brown hairs; style glabrous. Fruit not known.

Habitat: Thickets

Distribution: China (S Sichuan, NE Yunnan)

Altitude: 750-1800m

Nomenclature

Type: China, Yunnan, prope Tchen-fong-chan, haud procul a Takouan, Delavay (iso. E, K?)

Flags

Occurs in Countries: CN Altitude Ranges: 0 - 1,000m: 1,000 - 2,000m Subgenus: Tsutsusi Habit: Tree Fl. Colour: red

Chamberlain, D.F. & Rae, S.J. (1990) A Revision of Rhododendron IV Subgenus Tsutsusi. Edinburgh Journal of Botany 47(2):128

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Rhododendron augustinii Hemsley

Shrub up to 10 m, though often less. Young growth pilose or more rarely glabrous. Leaves narrowly elliptic to elliptic, more rarely very narrowly elliptic, acute to acuminate at the apex, cuneate at the base, usually evergreen, more rarely subdeciduous to deciduous, (4G-)50-100(~110) x 18~30(-40) mm, upper surface ± elepidote, glabrous or with fine filiform-acicular hairs along the midrib and/or the main veins, lower surface lepidote with distant golden or brown scales, the midrib with an indumentum of long, ± straight hairs, at least towards the base, this indumentum extending on to the petiole or not, petiole sometimes just puberulent. Inflorescences (2-)3(-5)-flowered, pedicels 8-22 mm, sparsely lepidote, sometimes puberulent. Calyx disc-like or obscurely lobed with lobes up to 3 mm, lepidote, often puberulent and variably ciliate. Corolla openly funnel-shaped, 28-40 mm, tube 11-16 mm, purple, lavender or almost blue, rarely white, with greenish or brownish spots inside, tube lepidote or sparsely pilose outside, pubescent within. Stamens 10, filaments pubescent towards the base. Ovary lepidote, variably pilose towards the apex.

Notes

A complex species, widely distributed and divisible into four subspecies

Flags

Occurs in Countries: CN Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: blue, brown, green, lavender, purple, white

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):72

Rhododendron augustinii subsp. augustinii

Leaves ± evergreen; corolla blue to purple with greenish or brownish spots. Petiole with filiform-acicular hairs only, or glabrous; corolla blue to lavender. Indumentum of leaf midrib beneath extending along the underside of the petiole; leaf upper surface with filiform-acicular hairs along most of the veins; corolla tube lepidote

Habitat: Rocky exposed sites and forest margins

Distribution: China (E Sichuan, Hubei, scattered)

Altitude: 1300-3000m

Illustrations:

  • Gard. Chron. 52:4 (1912)
  • Millais, Rhododendrons, opp. p. 24 (1917)
  • Urquhart, The Rhododendron 1: t. 6 (1958)
Notes

A distinct subspecies which vicariates with the more westerly subsp. chasmanthum; intermediates between the two occur in central and western Sichuan. R. vilmorinianum, on the basis of the type specimens, is clearly synonymous with subsp. augustinii; the description of vilmorinianum given by Balfour, and material identified as such by him and subsequent authors (Hutchinson, Davidian) is, however, a different plant which is known only in cultivation and is almost certainly a garden hybrid between R. augustinii and R. yunnanense. It has petioles and leaves fringed with loriform setae, the upper surface pubescent along the main veins and midrib, and a lepidote corolla tube; the leaf scales are like augustinii, but the characteristic patch of hairs on the midrib is lacking and the corolla is white or pink.

Nomenclature

Type: Hupeh, Patung distr., Henry 1420-1, 3736 (holo. K)

Synonymy: R. vilmorinianum Balfour f., Notes R.B.G. Edinb. 12:181 (1920) quoad typ. non descr. vel spec. cult. Type: material raised by Vilmorin, possibly from seed collected in E Szechuan by Farges (holo. E). R. augustinii var._yw/Fang, Contr. Biol. Lab. Sci. Soc. China 12:78 (1939). Type: China, Szechuan, Pao hsung hsien (Mupin), 2300- 2500 m, Yu 1976 (n.v.)

Rhododendron augustinii subsp. chasmanthum (Diels) Cullen

Leaves ± evergreen; corolla blue to purple with greenish or brownish spots. Petiole with filiform-acicular hairs only, or glabrous; corolla blue to lavender. Indumentum only on leaf midrib beneath, not or scarcely extending on to petiole; leaf upper surface glabrous or with filiform-acicular hairs along the midrib only; corolla tube elepidote, usually pilose outside.

Habitat: Forests, forest margins and scrub

Distribution: China (N & NW Yunnan, SW & NW Sichuan, SE Xizang)

Altitude: 2200-3650m

Illustrations:

  • Bot. Mag. 166: t. 79 (1949)
Notes

As mentioned above, subsp. chasmanthum vicariates with subsp. augustinii. The type of R. hirsuticostatum is somewhat intermediate between the two, but closer to subsp. chasmanthum than to subsp. augustinii

Nomenclature

Synonymy: R. chasmanthum Diels, Notes R.B.G. Edinb. 5:212 (1912). Type: China, Yunnan, Mekong/Salween Divide, NW of Tseku, 10-12000 ft, x 1904, Forrest 513 (holo. E). R. augustinii var. chasmanthum (Diels) Davidian, R.H.S. Rhodo. Yearbook 17:164 (1963). R. augustinii forma grandifolia Franchet, Journ. de Bot. 12:261 (1898). Type: China, Setchuen occidental (i.e. Yunnan), Tehrana pres de Tsekou, Soulie 1012 (holo. P—n.v., iso. E). R. augustinii forma subglabra Franchet, loc. cit. Type: China, Setchuen occidental (i.e. Yunnan), Tehrana pres de Tsekou, Soulie 1009, 1010 (iso. E). R. hirsuticostatum Handel-Mazzetti, Wien Akad. Anzeig. 27:27 (1920). Type: China, Szechuan, Schao-shan ad austro-or. urbis Ningyuen, 2200-2500 m, 15 iv 1914, Handel-Mazzetti 1353 (holo. WU—n.v., iso. E). R. chasmanthoides Balfour f. & Forrest, Notes R.B.G. Edinb. 13: 246 (1922). Type: China, Yunnan, Tseku, Soulie 1012 (holo. E)

Rhododendron augustinii subsp. hardyi (Davidian) Cullen

Leaves ± deciduous; corolla white with brownish spots

Habitat: Thickets and forests

Distribution: China (NW Yunnan)

Altitude: 3350-3650m

Notes

A very handsome shrub, separated from subsp. chasmanthum by characters that are not entirely clear cut (deciduousness of leaves, corolla colour)

Nomenclature

Synonymy: R. hardyi Davidian, Rhododendrons with Magnolias and Camellias 1974:47. Type: China, Yunnan/SE Tibet border, western range of Mekong on Kaakerpo, Doker la and Tsarung, 11500 ft, v-vi 1932, Rock 23010 (holo. E)

Rhododendron augustinii subsp. rubrum (Davidian) Cullen

Leaves ± evergreen; corolla blue to purple with greenish or brownish spots. Petiole with loriform as well as filiform-acicular hairs; corolla purple.

Habitat: Scrub and thickets,

Distribution: China (NW Yunnan)

Altitude: Around 4000m

Notes

A curious plant, known only from two gatherings and material in cultivation, in some respects (presence of loriform hairs, purple corolla) similar to R. trichanthum (p. 74). It is perhaps a naturally occurring hybrid, but field observations on this point are necessary.

Nomenclature

Synonymy: R. augustinii var. rubrum Davidian, R.H.S. Rhodo. Yearbook 17: 165 (1963). Type: China, Yunnan, Shiu-lu shan, 13000 ft, Forrest 25914 (holo. E). R. bergii Davidian, Quart. Journ. Amer. Rhodo. Soc. 30:210 (1976). Type: as for var. rubrum

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Rhododendron aureum Georgi

Dwarf shrub, 0.2- lm; young shoots ± glabrous; perulae persistent for up to four years. Leaves ovate to broadly elliptic, 2.5-15.5 X 1.2-7cm, 2-2.5 x as long as broad, apex rounded, base cuneate to rounded, upper and lower surfaces glabrous when mature; petioles 0.5-lcm, velutinous-tomentose. Inflorescence lax. 5-8-flowered; rhachis c.lOmm; pedicels 25-35mm, sparsely dendroid-pilose. Calyx 2-3mm, lobes rounded-triangular, pilose. Corolla widely campanulate, yellow, usually with at least a few flecks, 25-30mm. Ovary rufous-tomentose; style glabrous. Capsule c. 10 x 4mm.

Habitat: Alpine slopes

Distribution: USSR (C & E Siberia, Kamchatka, Sakhalin, Kuriles), Korea, Japan (Hokkaido, Honshu), N China (Jilin)

Altitude: 1500-2700m

Notes

See also Busch, Fl. Siber. Orient. Extremi (Ericaceae), 18 (1915)

8*. R x nikomontanum (Komatsu) Nakai, Bot. Mag. (Tokyo) 31: 242 (1917)- R. aureum x R. brachycarpum. Syn: R. chrysanthum Pallas var. nikomontanum Komatsu in Matsumura, Ic. Fl. Koisikav. 3:1.195 (1917). Described from Nikko in Japan. R. brachycarpum G. Don var. lutescens Koidzumi, Bot. Mag. (Tokyo) 30: 17 (1916). Type: Japan, Mt Ontakisan. Intermediate between the two parents, with the more robust habit and leaf shape of R. brachycarpum and the yellowish flowers of R. aureum. This taxon was first recognised as a hybrid by Ohwi (Fl. Japan (English version) 698, 1965).

Flags

Occurs in Countries: CN, JP, RU Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: yellow

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):313

Rhododendron aureum var. aureum

Leaves 2.5-6.5(—8)cm long; perulae persistent

Illustrations:

  • Pallas, Fl. Rossica t.30 (1784)
  • Busch, Fl. Siber. Orient. Extremi (Ericaceae) t.63 (1915)- both as R. chrysanthum
Nomenclature

Type: USSR, ad Lacum Baical, Georgi (LE, n.v.)

Synonymy: R. chrysanthum Pallas, Reise 3: 729 (1776). Type: USSR, Montes Sajanensium ut et Dauriae, totiusque Siberiae orientalibus. R. officinale Salisbury, Parad. Lond. t.80 (1807), superfluous name under R. aureum.

Rhododendron aureum var. hypopitys (Pojarkova) Chamberlain

Leaves 9- 15.5cm long; perulae usually deciduous

Notes

Var. hypopitys may be no more than a shade form of var. aureum but superficially the two taxa are sufficiently distinct to merit varietal rank.

Nomenclature

Synonymy: R. hypopitys Pojarkova in Fl. URSS 18: 721, t.l, f.l (1952). Type: USSR, in parte septentrionali jugi Schote-Alinj, 1934, Soczava (LE, n.v.)

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Rhododendron auriculatum Hemsley

Shrub or small tree, 2-6m; young shoots setulose-glandular. Leaves oblong to oblong-oblanceolate, 15-20(-30) x 4.5-8(-10)cm, 2.5-3(-3.5) x as long as broad, apex rounded, apiculate, base auriculate, margin fringed with small glands, lower surface with scattered villous hairs, especially on the midrib and main veins, also glandular, sometimes ± glabrous at maturity; petioles densely setulose-glandular, l-3cm. Inflorescence 6-15-flowered; rhachis 20-40mm; pedicels 20-25mm, stout, stipitate-glandular. Calyx c. 2mm, sparsely stipitate-glandular, lobes minute. Flowers fragrant. Corolla 7-lobed, funnel-shaped, white or cream to rosy pink, with greenish colouring inside at base, 80- 110mm. Stamens 14. Ovary densely stipitate-glandular; style glandular to tip. Capsule 20-35 x 8-10mm, cylindrical

Distribution: China (E Sichuan, W Hubei, E Guizhou)

Illustrations:

Nomenclature

Type: China, Hubei, Patung district, 1885, Henry 513 (holo. K)

Flags

Occurs in Countries: CN Subgenus: Hymenanthes Habit: Tree Fl. Colour: cream, green, pink, white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):241

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Rhododendron aurigeranum Sleumer

Notes

Latin – aurum – gold, alluding to the gold-mining area in which it was found to be abundant.

Nomenclature

Type: Lam 7753, 4 Oct. 1954. Papua New Guinea, Morobe District, Lae–Bulolo road above Patop Creek (L, CANB, SING).

Flags

Occurs in Countries: PG Altitude Ranges: 0 - 1,000m: 1,000 - 2,000m Subgenus: Vireya Habit: Tree Fl. Colour: orange, yellow

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:299

Rhododendron aurigeranum subsp. aurigeranum

Shrub or tree to 4m. Twigs 2–4mm in diameter, green, a little flattened and densely brown scaly; internodes 5–15cm. Leaves 4–7 in dense pseudowhorls at the upper 1–2 nodes and with 2–4 much smaller leaves associated. Blade 70–140 x 30–60mm, elliptic or broadly elliptic; apex acute, sub-acute or shortly acuminate; margin entire, slightly revolute; base tapering into the petiole, glabrescent above when mature, densely scaly beneath when young, less so in mature leaves. Scales small, brown, fra­gile, sessile or very shortly stalked, marginal zone irregularly and deeply stellate-incised; centre often extended into a short stalk, not or hardly impressed. Mid-vein broad at the base, narrowed and slightly impressed above, thick and prominent beneath; lateral veins 6–8 per side, rather straight below, curved and obscurely anastomosing before the edge, nearly smooth above, slightly raised beneath, reticulation inconspicuous on both sides. Petiole 7–12 x 3–5mm, grooved above, scaly. Flower buds to 34 x 6mm, broadly ovate, with the outermost bracts narrowly triangular, spreading and reflexing, as a collarette inside the foliage leaves, tips of the main bracts shortly triangular, spreading and reflexing, green, scaly. Bracts 15–20 x 4–10mm, ovate-acuminate, apex blunt or very shortly contracted into a sharp point, densely scaly on both sides at the apex, glabrous elsewhere, inner bracts obovate-elliptic to sub-spathulate, glabrous outside, all initially with scales along the margins. Bracteoles 10–15 x 1–2mm, linear-sub-spathulate. Inflorescence an 8–14-flowered complete umbel. Pedicels thick, 20–50 x 1–1.5mm, sub-densely stellately scaly, very laxly though distinctly shortly hairy. Calyx disc-shaped, wavy, c.3mm in diameter. Corolla funnel-shaped, orange or orange-yellow initially, fading to yellow, 60–80mm, laxly stellately scaly outside, laxly hairy in the lower ½ of the tube inside; tube 30–40 x 4–5 x 10–15mm, straight, markedly 5-angled; lobes 20–30 x 18–25mm, obovate, spreading. Stamens sub-equal, exserted to 15mm; filaments linear, sub-densely hairy in the proximal 1⁄3, glabrous distally; anthers 3.5–4 x c.1.3mm, broadly oblong, base obtuse. Disc very prominent, white-hairy at the upper margin. Ovary c.10 x 2.5mm, sub-conical-cylindrical, densely and shortly hairy and scaly, tapering distally; style densely hairy and scaly for the proximal ¾, densely and exclusively scaly for the subsequent c.2mm, glabrous for the upper c.10mm; stigma thick-globose and deeply 5-lobed. Fruit elongate-cylindrical, shortly tapering at the base, more gradually so at the apex, hairy and scaly, often curved, 60–100 x 5–6mm, the valves becoming twisted. Seeds 7–12mm including the tails.

Habitat: Occasionally in floating immature peat swamps in forest clearings, generally in dry grassy or shrubby hillsides together with Grevillea papuana Diels. or on schistes or steep rock. Locally common.

Distribution: Papua New Guinea, Morobe District, Mt Misim, Wagau, Mapos and in the Wau–Bulolo area.

Altitude: 915-1740m

Notes

The flower buds are very distinctive in this species, with short reflexed tips which are scaly both inside and out.

Rhododendron aurigeranum subsp. hirsutum Argent

Differing from the type subspecies by having both white hairs and scales on the outside of the corolla tube.

Habitat: It was growing at c.1520m in grassland above lower montane forest and appears to be well established as two collections were made 12 years apart from similar localities.

Altitude: Around 1520m

Notes

Latin – hirsutus – covered with long stiff hairs, alluding to the hairs on the outside of the corolla.

The flowers are described as yellow in one collection but with a yellow tube and salmon pink lobes in the other. Remaining colour in one of the herbarium sheets clearly indicates a yellow tube and pink or orange lobes.

Nomenclature

Type: Woods & Black 1121, 12 May 1968. Papua New Guinea, Morobe District, above Garaina, Saureli Bubu to Arabuka (E, A, L, LAE, SYD).

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Rhododendron auritum Tagg

Very similar to R. xanthostephanum, differing as follows: often taller, bark not as conspicuous, leaves narrowly elliptic to elliptic, undersurface brown with unequal, ± contiguous or overlapping scales, the smaller sunk in pits but reaching the leaf surface; calyx lobes reflexed; corolla pale yellow or cream, sometimes with a faint pink flush.

Habitat: Sheltered cliffs

Distribution: China (SE Xizang—Tsangpo gorge)

Altitude: 2150-2600m

Notes

Very similar to R. xanthostephanum but consistently distinguishable by the reflexed calyx lobes and the less deeply sunk scales.

Nomenclature

Type: China, S Tibet, Tsangpo gorge near Pemakochung, 8000 ft, 18 vi 1924, Kingdon Ward 6278 (holo. E)

Flags

Occurs in Countries: CN Altitude Ranges: 2,000 - 3,000m Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: cream, pink, yellow

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):128

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Rhododendron austiinum (Small) Rehder

Shrub or small tree to 5m tall, usually non-rhizomatous; young twigs red-brown, densely covered with unicellular hairs and multicellular gland-tipped hairs. Vegetative bud scales densely covered with unicellular hairs abaxially; margin glandular. Leaf blade membranaceous, ovate or obovate to elliptic, (4.7-)5.4-8.8(-10.0) x (2.1-)2.2-3.2(-3.9)cm; base acute to oblique; apex acute to obtuse, often mucronate; adaxial surface densely covered with unicellular hairs, or widi unicellular hairs and multicellular gland-tipped hairs, the midvein densely covered with unicellular hairs; abaxial surface densely covered with unicellular hairs, the midvein densely covered with unicellular hairs and multicellular gland-tipped hairs; margin entire, ciliate with multicellular eglandular and gland-tipped hairs; petiole 0.2-0.5cm long, densely covered with unicellular hairs and multicellular gland-tipped hairs. Flower bud scales chestnut brown; abaxial surface densely covered with unicellular hairs; margin glandular. Flowers appearing before or with the leaves; inflorescence a shortened raceme of 10 to 24 flowers. Pedicels (0.5-)0.6-l.l(-1.7)cm long, densely covered with unicellular hairs and multicellular gland-tipped hairs. Sepals less than 0.1-0.2cm long, often varying in length on the same flower; margins glandular-fimbriate; abaxial surface densely covered with unicellular hairs and multicellular gland-tipped hairs. Corolla yellow, apricot or orange to red-orange, fragrance musky-sweet, the tube longer than the limb and gradually expanding into it; upper corolla lobe 0.9-1.4(-l.8) x 0.6-1.2(-1.4)cm; lateral lobes (l.l-)1.2-1.7(-2.0)x0.5-0.9(-l.l)cm; corolla tube 1.8-2.3(-2.4)cm long, 0.2-0.4(-0.5)cm wide at base; outer surface of corolla sparsely to densely covered with unicellular hairs and multicellular gland-tipped hairs; inner surface of corolla sparsely to densely covered with unicellular hairs. Stamens (5.2-)5.4-6.8(-7.7)cm long, with dense terete or flattened unicellular hairs on proximal (2.5-)2.8-3.6(-3.7)cm of filament, exserted (3.3-)3.5-4.8(-5.7)cm beyond throat of corolla. Style (5.4-)5.5-6.8(-7.5)cm long, exserted (3.2-)3.6-4.9(-5.5)cm beyond throat of corolla, with dense unicellular hairs on proximal (0.3-)0.5-1.7(-2.2)cm; stigma 0.1-0.2(-0.3)cm wide. Ovary 0.3-0.5(-0.6)cm long, 0.1-0.2cm wide at the base, densely covered with multicellular gland-tipped hairs and unicellular hairs, or also with multicellular eglandular hairs. Capsules (1.4-) 1.6-2.3 (-2.5) x (0.3-)0.4-0.5cm, narrowly ovate, moderately to densely covered with unicellular hairs and sparsely to moderately densely covered with multicellular gland-tipped hairs. Seeds pale to dark chestnut brown, ovate or elliptic to fusiform, (l.l-)1.7-2.8(-2.9) x 0.7-0.9(-1.0)mm, body 1.0ó1.5(ó1.7) x (0.2-)0.3-0.5(-0.6)mm; testa expanded and dorsiventrally flattened, surrounding the body, the cells short throughout, with transverse end-walls

Habitat: Upland mixed mesic hardwoods, bluffs of rivers or stream banks, river bottoms, swamps

Distribution: USA: Florida pan-handle and adjacent Georgia, Alabama and Mississippi

Altitude: 0-100m

Illustrations:

Notes

Rehder (1947) described a new form of R. roseum (= R. prinophyllum) from Stewartstown, Pennsylvania, but the type specimen is indistinguishable from R. austrinum. Rehder states that the plant grew in the woods near Gable's home in Stewartstown, although it is most likely an escape from cultivation.

Rhododendron austrinum is most closely related to R. luteum and R. occidentale. It is quite variable in flower colour, ranging from yellow to orange with a dark pink to red tube. Morphologically, it resembles R. canescens but can be distinguished from it by the consistently glandular nature of the bud-scale margins, pedicels, petioles and leaf margins. It is interesting to note that while the bud-scale margins of R. canescens can be mixed glandular and unicellular-ciliate in some populations, this character state is restricted to populations in central Georgia where R. austrinum does not occur. In areas where R. canescens is sympatric with R. austrinum the bud-scale margins of the former are consistently eglandular, as are the pedicels, petioles and leaf margins. These two species are usually isolated ecologically: R. canescens usually occurs in stream bottoms or low areas, and R. austrinum in upland woods. Hybrids do occur, however, and these usually appear intermediate in flower colour, but retain the eglandular nature of R. canescens. Specimens from Jackson Co., Mississippi are apparently R. austrinum, but those from neighbouring George Co. are entirely like R. canescens except for the orange-red flower colour noted on the label. Whether these specimens represent natural hybrids or whether they are cultivated hybrids is not possible to determine without further information.

Flowering from March to April; occasionally as late as May.

Chromosome number: 2n = 26 (Janaki-Ammal et al., 1950; Li, 1957)

Nomenclature

Synonymy: Azalea austrina Small, FL S.E. US ed. 2. 1356, 1375 (1913). Type: Wooded hillsides, Chattahoochee, Florida, iv and x, Curtiss 1718* (holo. NY). Rhododendron roseum (Loisel.) Rehder f. lutescens Rehder, Contr. Gray Herb. 165:9 (1947). Type: Pennsylvania: J. P. Gable, Stewartstown, Rehder s.n. (holo. A).

Flags

Occurs in Countries: US Altitude Ranges: 0 - 1,000m Subgenus: Pentanthera Habit: Tree Fl. Colour: apricot, orange, red

Kron, K.A. (1993) A Revision of Rhododendron Section Pentanthera. Edinburgh Journal of Botany 50(3):293

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Rhododendron baconii Argent, A.Lamb & Phillipps

Shrub or tree to 9m. Twigs smooth, green, sparsely scaly when young. Leaves 4–6 in tight pseudowhorls between which are scattered scale leaves that soon fall off. Blade 35–80 x 15–35mm, elliptic to broadly elliptic; apex rounded or retuse; margin entire, strongly recurved even in the fresh state in fully mature leaves; base rounded or broadly tapering; sparsely scaly, quickly becoming glabrescent above and often beneath as well, smooth. Scales variable in size, slightly impressed, sub-circular to lobed, mostly with small centres and relatively broad flanges. Mid-vein impressed above and strongly raised below throughout its length; lateral veins 4–6 per side, widely spreading, very slightly raised beneath, almost smooth and fairly obscure above. Petiole 1–2 x 2.5–3mm, sparsely scaly, weakly grooved above. Flower buds to 20 x 13mm, pale green, ovoid, the scales thick and fleshy, the broadly tapering points reflexed well away from the surface of the bud. Outer bracts fringed with minute brown scales along their edges and evenly covered with very fine, minute, patent white hairs on the outer side and also on the inner, near the apex. Bracteoles 11–14 x c.1mm, linear, hairy outside. Inflorescence 3–6-flowered, (8 in cultivation), the flowers displayed horizontally to half-hanging in an open umbel. Pedicels 23–32 x c.2mm, densely hairy and with a few scales. Calyx 3mm in diameter, a low hairy ring or with broad, well-marked lobes. Corolla 30–35 x 33–40mm, pink, not scented; tube 17–22 x 8–10 x 12–15mm, scaly outside, hairy near the base inside; lobes c.18 x 16–20mm, slightly emarginate, spreading almost to right angles, overlapping to c.2⁄3, finely scaly outside. Stamens arranged regularly all round the flower, distinctly dimorphic to about ½ the length of the anthers; filaments 15mm, pink, with spreading hairs in the proximal 1⁄3; anthers 3mm, pale brown. Ovary 3.5 x 2.5mm, densely hairy with spreading hairs and a sparse covering of silvery scales; style 6–13mm, hairy in the proximal 1⁄3; stigma 2mm in diameter, glossy red, central in position. Fruit to 14 x 7mm, softly hairy. Seeds 2.4mm, without tails 1.2mm, the longest tail 0.8mm.

Habitat: Low ridge forest or more open shrub-covered ridges.

Distribution: Malaysia (Borneo), Sabah, Mt Tambuyukon endemic

Altitude: 2000-2500m

Notes

Named in honour of Andrew Bacon, a keen Sabah naturalist, who participated in the ascent of Mt Tambuyukon on which the first flowering material of this species was collected.

Nomenclature

Type: Argent & Walpole 1459, 12 March 1980. Malaysia, Sabah, Kinabalu N.P., G. Tambuyukon (E, SAN).

Flags

Occurs in Countries: MY Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Vireya Habit: Tree Fl. Colour: pink

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:267

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Rhododendron baenitzianum Lauterb.

Shrub to 2m. Twigs 3–6mm in diameter, rounded, densely sub-stellately scaly at first, becoming glabrescent; internodes 3–10cm. Leaves 5–10 in tight pseudo­whorls, sub-sessile or shortly petioled. Blade 120–250 x 30–85mm, elliptic to ovate-elliptic; apex sub-caudate-acuminate or acute; margin flat; base obtusely or broadly acutely tapering, rarely rounded, often unequal, glabrescent above at maturity; laxly scaly beneath. Scales small, flat, marginal zone irregularly lobed; centre small, weakly or not impressed, finally glabrescent beneath and then with dark spots. Mid-vein narrow and impressed above, broader and bluntly prominent beneath; lateral veins 8–12 per side, ascending, curved-anastomosing before the margin, the major veins distinctly grooved above, prominent beneath, reticulation finely raised on both sides. Peti­ole 3–4 x 2–3mm, semi-rounded, grooved above, scaly. Bracts to 25 x 10mm; outer bracts ovate to obovate, cuspidate or shortly acutely acuminate, laxly scaly outside and on the margins, shortly appressed hairy in the middle or towards the apex; inner bracts sub-spathulate, acuminate, laxly scaly outside, but not hairy. Bracteoles to 20mm, filiform to linear-sub-spathulate, sub-glabrous. Inflorescence 4–15-flowered, in a complete umbel. Pedicels 25–55 x c.1.5mm, laxly scaly especially at base and apex, without hairs. Calyx c.4mm in diameter, sub-oblique, rim-like. Corolla 75–100mm, funnel-shaped, yellow with orange or pink lobes; tube 50–60 x 6–8 x 20–25mm, pouched at the base, laxly scaly outside, shortly hairy inside; lobes 30–40 x 25–30mm, spreading, broadly obovate to sub-circular. Stamens sub-equal, exserted to c.15mm; filaments linear, shortly patently hairy in the proximal ½, glabrous distally; anthers c.4 x 1.2mm, oblong. Disc hairy on the upper margin, glabrous below. Ovary 10–12 x 2–2.5mm, sub-cylindrical, shortly and densely covered with distally pointing hairs and with scales, tapering gradually distally; style equalling the stamens when receptive, densely covered with sub-patent hairs and with scales to near the top; stigma thick, 5-lobed. Fruit 150–200 x 4–5mm, elong­ate-fusiform, often curved, laxly hairy and scaly.

Habitat: Terrestrial along rivulets or in rocky places

Distribution: Papua New Guinea, East Sepik Province, Torricelli Mts; Maboro Range; West Sepik Province, Telefomin; Waria R. region; Bundi to Simbu road; Mendi S District, Kawkawsaw Humu; Southern Highlands Province, Kagua District, Lamame, Vulkara Range; Milne Bay District, Mt Suckling.

Altitude: 215-1600m

Notes

Named after Carl G. Baenitz, German botanist and teacher.

Reported as being visited by a large butterfly by Tom Reeve in 1978. There is a letter in the Sydney Herbarium from T.L. Fenner, of the Department of Primary Industry, with the specimen, confirming the butterfly as Papilio euchenor.

Nomenclature

Type: Schlechter 14357, April 1892. New Guinea (E), Torricelli Mts (B†, BO, BRSL, K).

Flags

Occurs in Countries: PG Altitude Ranges: 0 - 1,000m: 1,000 - 2,000m Subgenus: Vireya Habit: Non-Tree Fl. Colour: orange, pink, yellow

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:320

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Rhododendron bagobonum H.F.Copel.

Shrub to 1m. Twigs 1–1.5mm, slender, rounded, tips laxly scaly and sometimes shortly patently hairy; internodes 1–5cm. Leaves 6–15 together in loose pseudo­whorls. Blade 15–27 x 5–12mm, spathulate-elliptic to obovate; apex broadly acute to obtuse or broadly acute; margin flat or slightly revolute when dry, minutely crenulate; base long-tapering; glabrous and shiny above; laxly to sub-densely and persistently scaly beneath. Scales with the marginal zone irregularly lobed; centre small, impressed. Mid-vein narrowly impressed above, flat or slightly raised in the proximal ½ beneath; lateral veins obscure. Petiole 0.5–2.5 x 1mm, weakly to distinctly grooved above, laxly scaly. Flower buds to 16 x 6mm, ovoid with an acute, subulate point, glossy green flushed with red. Bracts to 14 x 3mm, narrowly ovate-acuminate or elliptic, shortly subulate, membranous, glabrous. Bracteoles c.5mm, linear-spathulate. Flowers solitary, occasionally paired, stiffly held, horizontal to half-hanging. Pedicels 4–6 x c.2mm, densely, shortly, patently hairy and scaly. Calyx c.2.5mm in diameter, disc-shaped, obscurely obtusely 5-lobed, sparsely scaly and hairy. Corolla 12–16 x 8–9mm, tubular, red or orange; tube 7–15 x 4–6 x 4–5mm, straight, laxly scaly outside, laxly hairy in the proximal ½ inside; lobes 3–4 x 3–4mm, sub-erect, ovate to sub-circular. Stamens slightly dimorphic, as long as the corolla tube, arranged regularly in the mouth of the corolla; filaments flat, linear, laxly patently hairy in the proximal ½; anthers 1mm, obovoid. Disc low, glabrous. Ovary 4–5 x c.2.5mm, sub-ovoid-cylindrical, densely hairy and scaly (the scales covered by the hairs), abruptly contracted distally; style c.4mm, columnar, glabrous, central or lying on the lower side of the mouth. Fruit 20–25 x 3.5–4.5mm, fusiform, with a short sub-persistent style, laxly hairy and scaly. Seeds narrow-fusiform, c.3mm including the long tails.

Habitat: Mostly epiphytic in primary montane forest on mountain ridges, also in heath-forest, and colonising roadsides and landslips, locally common.

Distribution: Philippines, Mindanao, Mt Apo, Camiguin Is., Mt Hibok-hibok; Palawan, Mt Mantalingajan. Malaysia (Borneo), Sarawak, Mt Penrissen, Mt Mulu, Kelabit Highlands (4th Div.), Baru Laga Plateau (7th Div.). Sabah, Mt Kinabalu, Mt Alab, Mt Lotung. Indonesia, Sulawesi, Mt Sojol; Maluku, Mt Binaia.

Altitude: 900-2135m

Notes

Named after the ‘Bagobones’ – an ethnic group in the southern Philippines.

Nomenclature

Type: Clemens s.n. Philippines, Mindanao, Davao, Mt Apo (UC).

Synonymy: R. cuneifolium Stapf var. subspathulatum Ridl., J. Str. Br. R. As. Soc. 1900. 33: 23. R. galioides J.J.Sm., Bull. Jard. Bot. Buit. III, 1935. 13: 445.

Flags

Occurs in Countries: ID, MY, PH Altitude Ranges: 0 - 1,000m: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Vireya Habit: Epiphyte, Non-Tree Fl. Colour: orange, red

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:213

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Rhododendron baileyi Balfour f.

Shrub, 0-5-2 m. Leaves very narrowly elliptic to elliptic, rarely obovate or ovate, obtuse to rounded at the apex, cuneate to rounded at the base, (21-)30-50 X (10-)14-19(-26) mm, upper surface densely lepidote when young, the scales quickly deciduous, lower surface usually dark brown with dense, overlapping scales. Inflorescence (4-)5-8-flowered, rachis elongate, pubescent, pedicels 12-22 mm, lepidote. Calyx 5-lobed, the lobes ± deltoid, (1 ■ 5-)2-4 mm, lepidote, often fringed with loriform setae. Corolla magenta to purple, often with darker spots, 12-14.5 mm, tube 5-7(-9) mm, usually densely lepidote outside, especially on the tube. Capsule lepidote, 5-7.5 mm

Habitat: Forests, hillsides, screes or rocks

Distribution: India (Sikkim), Bhutan, China (S Xizang)

Altitude: 3050-4250m

Illustrations:

Notes

A uniform and easily recognised species. One specimen, Ludlow, Sherriff & Hicks 20659, has remarkable dendroid hairs fringing the calyx

Nomenclature

Type: a cultivated plant supposedly derived from Bailey 5, seed collected in S Tibet (holo. E)

Synonymy: R. thyodocum Balfour f. & Cooper, Notes R.B.G. Edinb. 11:148 (1919). Type: Bhutan, Champa Pumthang, 14000 ft, 23 ix 1914, Cooper 2224 (holo. E)

Flags

Occurs in Countries: BT, CN, IN Altitude Ranges: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: purple

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):151

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Rhododendron bainbridgeanum Tagg & Forrest in Stevenson (ed.)

Shrub, 0.6—2m; young shoots covered in glandular setae. Leaves obovate to elliptic, 8-12 x (2.5-)3-4cm, 2.3-3.2 x as long as broad, apex rounded, acuminate, base rounded to cordate, upper surface glabrous, lower surface with a continuous felted dark brown indumentum intermixed with glands which are prominent on midrib towards base; petioles 1—2cm, covered with stipitate glands. Inflorescence lax, 4-8-flowered; rhachis c.3mm; pedicels 20-25mm, stipitate-glandular. Calyx 3-6mm, stipitate-glandular, lobes rounded, unequal. Corolla campanulate, white to creamy yellow, usually flushed with pink, with a broad blotch and purple flecks, 30-35mm. Ovary densely stipitate-glandular; style usually glandular at base. Capsule 15-20 x 4-5mm.

Habitat: Scrub, conifer forests, etc.

Distribution: China(SE Xizang, NW Yunnan), NE Upper Burma

Altitude: 3350-4000m

Notes

Closely allied to R. selense and probably hybridising with it.

Nomenclature

Type: China, SE Xizang, Tsarong, Salween/Kiu-chiang divide, E of Chamatong, vi 1922, Forrest 21761 (holo. E).

Flags

Occurs in Countries: CN, MM Altitude Ranges: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: cream, pink, purple, white, yellow

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):277

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Rhododendron balfourianum Diels

Shrub, l-4.5m. Leaves ovate-lanceolate to elliptic, 4.5-12 x 2-4cm, 2-2.3 x as long as broad, apex acute to acuminate, base rounded, lower surface with a dense compacted to spongy unistrate lanate ramiform tomentum, silvery white when young, sometimes turning pale pinkish-cinnamon at maturity, usually shining and with a thin surface film; petioles 1 -2cm, glabrescent. Inflorescence 6-12-flowered; rhachis less than 5mm; pedicels 10-20mm, sparsely hairy and glandular. Calyx 6-10mm, glandular, lobes elliptic, rounded, glandular-ciliate. Corolla campanulate, pale to deep pink, with purple flecks, 35-40mm. Ovary glandular; style glandular in the lower third. Capsule 10-20 x c.7mm.

Habitat: Rocky slopes, Rhododendron thickets

Distribution: China (W Yunnan, SW Sichuan)

Altitude: 3350-4550m

Illustrations:

Notes

There is no clear dividing line between var. balfourianum, with a compacted leaf indumentum, and var. aganniphoides, with a thick spongy indumentum; the two taxa are therefore not maintained as distinct. R. balfourianum resembles R. aganniphum in its foliage but the latter may be distinguished by its short calyx and glabrous ovary. The silvery leaf indumentum, sometimes turning pinkish, distinguishes the present species from the allied R. adenogynum.

Nomenclature

Type: China, W Yunnan, eastern flank of the Tali Range, 25°40'N, 11 — 12000ft, vii 1906, Forrest 4166 (holo. E; iso. A, K)

Synonymy: R. balfourianum Diels var. aganniphoides Tagg & Forrest, Notes R.B.G. Edinb. 15: 306 (1927). Type: China, SW Sichuan, mountains around Muli, 28°12'N, 100°50'E, 12000ft, vi 1921, Forrest 20456 (holo. E)

Flags

Occurs in Countries: CN Altitude Ranges: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: pink, purple

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):341

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Rhododendron banghamiorum (J.J.Sm.) Sleumer

Shrub to 1.2m, slenderly branched. Twigs c.2mm in diameter, rounded, laxly scaly; internodes 2–5cm. Leaves 5–7 together in tight pseudowhorls. Blade 20–35 x 5–10mm, narrowly obovate; apex rounded, shortly retuse; margin slightly revolute, entire or sub-crenulate; base tapering, decurrent; initially sub-densely scaly on both sides, glabrescent above, persistently scaly beneath. Scales small, marginal zone irregularly stellately divided, quickly disintegrating; centre small, red brown, impressed. Mid-vein impressed above, obtusely prominent in the proximal ½ beneath, becoming flat distally; lateral veins and reticulation obscure. Petiole 1–2 x c.1mm, flattened. Bracts to 6 x 4mm, ovate-sub-acuminate, glabrous and shining outside. Bracteoles c.8mm, filiform below, sub-spathulate distally, glabrous. Inflorescence 2–3-flowered, sometimes reduced to a solitary flower. Pedicels 12–15mm, slender, densely stellate-scaly, without hairs. Calyx c.3mm in diameter, shortly cup-shaped, mostly very oblique, densely scaly, with obtuse lobes to c.1mm. Corolla c.20mm, open campanulate, membranous, red, lobed to halfway; tube c.10 x 3–4 x c.10mm, laxly scaly outside, glabrous inside; lobes c.10 x 6–7mm, obovate-sub-spathulate. Stamens c.12mm, exserted to c.6mm, slightly unequal; filaments linear, sub-densely patently hairy proximally; anthers c.2 x 1.2mm, broadly oblong. Disc glabrous. Ovary c.4 x 2mm, ovoid-conical, abruptly contracted distally, densely scaly; style 6–8mm, slender, glabrous; stigma rounded.

Distribution: Indonesia, N Sumatra, Gajo Lands, Redelong Volcano.

Altitude: Around 1830m

Notes

Named after the collector, W.N. Bangham, an American who collected in Sumatra with his wife for the Arnold Arboretum.

Previously known only from the type collection, it was recently re-found and introduced into cultivation by Paul Smith from Mt Banda Hara in 2001. It is superficially similar to R. pubigermen but has much longer, more slender leaves as well as lacking hairs on the ovary. It has not been cultivated for long enough to know how it will perform as it only flowered for the first time in Edinburgh in 2005.

Nomenclature

Type: Bangham 917, Dec. 1931–Feb. 1932. Sumatra, Atjeh, Redelong Volcano, c.1830m (A, K, SING).

Synonymy: R. pubigermen J.J.Sm. var. banghamiorum J.J.Sm. in Merr., Contr. Arn. Arb. 1934. 8: 123.

Flags

Occurs in Countries: ID Altitude Ranges: 1,000 - 2,000m Subgenus: Vireya Habit: Non-Tree

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:195

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Rhododendron barbatum [Wallich ex] G. Don

Large shrub or small tree, 1.5-6m; young shoots with long stiff bristles (rarely glabrous). Leaves elliptic to obovate, (9-)l 1-19 x 3.5-6.5cm,c.3 x as long as broad, apex acute to acuminate, base rounded to cuneate, upper surface ± glabrous, lower surface with scattered dendroid hairs and stipitate glands, with or without bristles on the midrib; petioles l-2cm, glabrous or with a dense covering of glandular bristles. Inflorescence dense, 10-20-flowered; rhachis c.5mm; pedicels 5-10mm, glabrous. Calyx cupular, 10-15mm, often with reddish tints, glabrous or with a few hairs at base, lobes well-developed, rounded, erose. Corolla fleshy, tubular-campanulate, crimson to blood-red, with darker nectar pouches, rarely pure white, 30-35mm. Ovary densely stipitate-glandular, also with some dendroid hairs; style glabrous. Capsule 15-20 x c.5mm, curved.

Habitat: Open slopes, amongst scrub, Abies forest, etc.

Distribution: N India (Uttar Pradesh, Sikkim, Bengal, W Arunachal Pradesh), China (S Xizang), Nepal, Bhutan.

Altitude: 2700-3700m

Illustrations:

Notes

Closely allied to R. smithii. Natural hybrids between R. barbatum and R. arboreum are recorded.

Nomenclature

Type: Nepal, Gopain Than, Wallich 757 (holo. K)

Synonymy: R. nobile Wallich, pro parte, nomen nudum. R. lancifolium Hooker f., Rhododendrons Sikkim Himalaya t.4 (1849). Type: Sikkim, Hooker (holo. K).

Flags

Occurs in Countries: BT, CN, IN, NP Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Hymenanthes Habit: Tree Fl. Colour: crimson, white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):380

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Rhododendron barkamense Chamberlain

Shrub, 4.5m. Leaves ovate, 5.5-7 x 4-4.7 cm, 1.4-1.9 x as long as broad, apex apiculate, base cordate, lower surface covered with a thin brown velutinous tomentum composed of radiate hairs; petioles c.lcm, finely tomentose. Inflorescence c.7-flowered; rhachis c.l2mm; pedicels 7-10mm, with a thin discontinuous tomentum. Calyx c. 1mm, ± glabrous, lobes rounded. Corolla open-campanulate?, c.35mm, pale yellow with purple flecks. Ovary and style glabrous. Capsule not known.

Distribution: China (N Sichuan)

Altitude: Around 3800m

Notes

Allied to R. lacteum with which it shares yellow flowers and a radiate leaf indumentum, but with smaller leaves with cordate bases and smaller flowers with glabrous ovaries.

Nomenclature

Type: China, N Sichuan, Barkam Xian (Ma-erh-Kang), Gong Zhang Mts, 3800m, 20 vi 1957, Li, X. 71626 (holo. PE)

Flags

Occurs in Countries: CN Altitude Ranges: 3,000 - 4,000m Subgenus: Hymenanthes Habit: Non-Tree

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):363

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Rhododendron basilicum Balfour f. & W. W. Smith

Shrub or small tree, 3-10m. Leaves obovate to oblanceolate, 17-25 x 8.5-13cm, 1.8-2.4 x as long as broad, apex ± rounded, base cuneate, upper surface giabrescent, with deeply impressed veins, lower surface with a bistrate indumentum, the lower layer compacted, the upper thick, greyish at first, usually soon becoming rufous, composed of only slightly fimbriate, broadly cup-shaped hairs; petioles 2—3cm, strongly flattened and winged, giabrescent. Inflorescence 15-25-flowered; rhachis 30-60mm; pedicels 30-40mm, sparsely grey- to rufous-tomentose, eglandular. Calyx c.2mm, tomentose, lobes rounded. Corolla fleshy, 8-lobed, obliquely campanulate, pale yellow with a crimson blotch, 35-50mm. Stamens 16. Ovary densely rufous-tomentose. Capsule 20-30 X 7-10mm, straight or curved.

Habitat: Abies forests, Rhododendron thickets, open slopes

Distribution: NE Burma, China(W Yunnan)

Altitude: 3000-3700m

Notes

Closely allied to R. semnoides (q.v.). The following specimens are intermediate between R. basilicum and R. rex subsp. arizelum and are probably hybrids: Forrest 8990, 17691, 18116, 18375, 18860, 23284. These may be distinguished from R. basilicum by their only slightly flattened, scarcely winged petioles and by the strongly fimbriate cup-shaped hairs on the leaves.

Nomenclature

Type: China, Yunnan, Shweli/Salween divide, vi 1913, Forrest 12078 (holo. E; iso. A, K)

Synonymy: R. megaphyllum Balfour f. & Forrest, Notes R.B.G. Edinb. 12: 138 (1920). Type: China, W Yunnan, Shweli/Salween divide, 11000ft, vi 1918, Forrest 17650 (holo. E). R. regale Balfour f. & Kingdon-Ward, Notes R.B.G. Edinb. 12: 156 (1920). Type: NE Upper Burma, Htawjaw, valley Naumchaung, 12000ft, 19 v 1914, Kingdon-Ward 1565 (holo. E). R. gratum T. L. Ming, Acta Bot. Yunnanica 3: 118 (1981). Type: China, W Yunnan, Yunlong Xiang, Chaojian, Zibeng Shan, 3200m, 21 iv 1980, C. H. Yang 80-0008 (holo. Herb. Inst. Bot. Kunming; iso. E).

Flags

Occurs in Countries: CN, MM Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Hymenanthes Habit: Tree Fl. Colour: crimson, yellow

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):253

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Rhododendron bathyphyllum Balfour f. & Forrest

Dwarf shrub, 0.6-1.5m. Leaves elliptic to oblong, 4-7 x 1.5-2cm, 2.7-3.5 x as long as broad, apex ± cucullate, base rounded, lower surface with a dense bistrate indumentum, the upper layer dark rufous-brown, loosely and finely ramiform-tomentose, the lower layer compacted; petioles 0.5 -1.5cm, densely brown-tomentose. Inflorescence 10-15-flowered; rhachis c.5mm; pedicels 10-15mm, glabrescent. Calyx c.0.5mm, glabrous. Corolla campanulate, white flushed rose, with crimson flecks, 30-35mm. Ovary densely rufous-tomentose; style glabrous. Capsule c. 10 x 5mm.

Habitat: Bouldery slopes, thickets, margins of pine forests, etc.

Distribution: China (SE Xizang, NW Yunnan)

Altitude: 3350-4250m

Notes

R. bathyphyllum has close affinities with R. roxieanum var. cucullatum and R. alutaceum var. russotinctum but differs from both in its densely tomentose, eglandular ovary, etc.

Nomenclature

Type: China, SE Xizang, on Ka-gwr-pw, Mekong/Salween divide, 28°30'N, 13000ft, viii 1917, Forrest 14718 (holo. E)

Flags

Occurs in Countries: CN Altitude Ranges: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: crimson, rose, white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):348

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Rhododendron beanianum Cowan

Straggling shrub, up to 3m; young shoots stellate-setose and stipitate-glandular. Leaves obovate to elliptic, 6-9 x 3.2-4.4cm, 2-2.4 x as long as broad, apex rounded, apiculate, base + rounded, upper surface rugulose, glabrous, lower surface with a dense unistrate fulvous dendroid-tomentose indumentum; petioles 1.5-2cm, setulose to tomentose. Inflorescence 6—10-flowered; rhachis c.5mm; pedicels 10- 15mm, setulose-tomentose. Calyx c.5mm, cupular, sparsely tomentose. Corolla fleshy, tubular-campanulate, carmine to blood-red, c.35mm. Ovary stellate-tomentose. Capsule at least 12 X 6mm, persistently tomentose.

Habitat: Bamboo forests, rocky gullies

Distribution: NE Upper Burma, ne India (Arunachal Pradesh)

Altitude: 3000-3350m

Illustrations:

Notes

Closely allied to R. piercei (q.v.)

Nomenclature

Type: China, Xizang, Seingku Wang, 10000ft, 1 vi 1926, Kingdon-Ward6805 (holo. BM; iso. K)

Flags

Occurs in Countries: IN, MM Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: carmine

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):386

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Rhododendron beccarii Sleumer

Apparently small shrub. Twigs 4–8mm in diameter, rounded, with lax sub-stellate, appressed scales when young, becoming glabrescent, smooth, and pale; internodes 5–17cm. Leaves 5–8 together in pseudowhorls, sub-sessile. Blade 100–160 x 40–60mm, elliptic to ovate-elliptic, apex gradually long-acuminate (2–3cm), acute, or nearly so; margin slightly revolute; base broadly tapering, extreme base sub-truncate, glabrescent at maturity, but remaining blackish punctate above; laxly and more persistently scaly beneath but eventually glabrescent and punctate beneath too. Scales small, marginal zone irregu­larly sub-stellately lobed; centre minutely impressed. Mid-vein 2–4mm wide, obtusely prominent on both sides proximally; lateral veins 10–12 per side, obliquely ascending, faintly interarching before the margin, little raised on both sides, sometimes hardly visible, reticulation obscure. Petiole 0–2 x 2–4mm, flattened. Flower buds 30–35 x 10–15mm, ovoid-acuminate. Bracts to 30 x 10mm; outer bracts ovate, acuminate, inner ones oblong-ovate, all sub-acute, glabrous outside, margin initially scaly. Bracteoles to 25 x 0.5mm, filiform, glabrous. Inflorescence 4–6-flowered. Pedicels 20–30mm, laxly scaly. Calyx c.4mm in diameter, oblique, disc-shaped, obscurely lobed, sub-glabrous. Corolla 50–65mm, funnel-shaped, red or orange; tube 30–35 x 5–6 x 15–20mm, lobed at the base, sub-cylindrical near the base, gradually widened distally, glabrous outside, densely shortly white-hairy in the proximal ½ inside; lobes 20–30 x 15–20mm, obovate spathulate. Stamens unequal, the longest nearly as long as the corolla; filaments linear and densely sub-patently white-hairy proximally, filiform and glabrous distally; anthers c.4 x 1mm, oblong, base obtuse. Disc prominent, glabrous. Ovary c.10 x 2.5mm, sub-cylindrical, glabrous or very laxly scaly, tapering distally; style nearly as long as the corolla tube, glabrous; stigma rounded. Fruit 40–60 x 6–7mm, sub-fusiform, red, slightly curved, glabrous.

Distribution: Indonesia, Sumatra, West Coast: Mt Singgalang, Mt Sago. Epiphytic in montane mossy forests.

Altitude: 1400-2450m

Notes

Named after the famous Italian collector and early explorer Odoardo Beccari.

Apparently rare, not recently recollected and never cultivated. The status of this species is still very uncertain. The differences between this species and R. sessilifolium remain matters of degree. The orange or red flower colour suggests that this might be a hybrid between R. sessilifol­ium and perhaps R. rarilepidotum.

Nomenclature

Type: Beccari P.S. 218, Giugno-Luglio 1878. Sumatra, West Coast, Mt Singalang, c.1700m (FI, BM, K, L, MEL).

Flags

Occurs in Countries: ID Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Vireya Habit: Non-Tree Fl. Colour: orange, red, white

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:253

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Rhododendron beesianum Diels

Shrub or tree, 1.8—9m. Leaves oblanceolate to elliptic, 9-19 x 2.6-8.2cm, 3—5.3 x as long as broad, apex apicuiate, base attenuate to rounded, lower surface with a thin unistrate compacted fawn to brown indumentum composed of radiate hairs; petioles 1.5-2cm, sometimes winged, glabrous or floccose. Inflorescence 10-25-flowered; rhachis c.25mm; pedicels 15-25mm, sparsely hairy. Calyx 0.5- 1mm, glabrous, lobes rounded. Corolla broadly campanulate, white flushed rose to pink, with or without purple flecks and a basal blotch, 35-45(-55)mm. Ovary densely white- to brown-tomentose; style glabrous. Capsule 20-45 x 6-9mm, curved.

Distribution: China (SE Xizang, NW Yunnan, SW Sichuan), NE Upper Burma.

Illustrations:

Notes

In general form R. beesianum resembles R. uvarifolium (subsection Fulva) but its leaf indumentum suggests a closer affinity with R. nakotiltum and R. dignabile.

Nomenclature

Type: China, Yunnan, E Flank of the Lichiang Range, 11 —12000ft, v 1906, Forrest 2323 (holo. E; iso. K)

Synonymy: R. colletum Balfour f. & Forrest, Notes R.B.G. Edinb. 11: 39 (1919). Type: China, W NW Yunnan, Mekong/Salween divide, 11000ft, vii 1917, Forrest 14450 (holo. E; iso. K). R. emaculatum Balfour f. & Forrest, ibid. 13: 42 (1920). Type: China, SE Xizang, Tsarong, Dokar-la, Mekong/Salween divide, vii 1917, Forrest 14352 (holo. E; iso. K).

Flags

Occurs in Countries: CN, MM Subgenus: Hymenanthes Habit: Tree Fl. Colour: pink, purple, rose, white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):365

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Rhododendron beyerinckianum Koord.

Slender, loosely branched, erect shrub or small tree to 5m. Twigs 1.5–4mm in diameter, thick to slender, densely to very densely covered with deep brown stellate scales which easily fall off and are absent from the older parts which are brown and rough with the numerous fine persistent tubercles; internodes 1.5–10cm. Leaves 3–7 together in pseudowhorls, often variable in shape and size in the same whorl. Blade 30–60 x 10–35mm, narrowly ovate, to broadly elliptic, obovate or sub-circular; apex obtuse, broadly acute, sometimes apiculate; margin strongly revolute to almost flat and more densely and often more persistently scaly than the rest of the leaf beneath; base broadly tapering or rounded; very densely reddish-brown scaly on both sides at first, quickly glabrescent especially above where it can become shiny but rough, more persistently scaly below. Scales irregularly stellately divided to the centre, dendroid, very fragile, each from the top of a minute, persistent, epidermal tubercle. Mid-vein slightly impressed above, strong and prominent beneath; lateral veins 4–7 per side, straight below, curved and anastomosing before the margin, very slightly impressed above and raised beneath, often inconspicuous or completely covered by the scales beneath, reticulation dense, visibly prominent on both sides in fully mature leaves, occasionally slightly impressed above. Petiole 4–15 x c.2mm, weakly grooved in the distal ½, or the groove inconspicuous, densely covered with brown stellate scales. Flower buds c.12 x 8mm, densely brown scaly with erect to slightly spreading bract points. Bracts to 10 x 7mm; the outer ones ovate subulate, densely scaly outside and fringed with marginal scales; the inner ones ovate acuminate and apiculate. Bracteoles to 10mm, linear and glabrous or scaly at first proximally, sub-­spathulate and laxly hairy distally. Inflorescence a 1–5-flowered open umbel. Flowers horizontal to half-hanging. Pedicels 10–15 x 7–10mm, densely brown-stellate scaly, becoming glabrescent. Calyx 3–4mm in diameter, disc-shaped or cup-shaped, densely stellate scaly or shallowly and obtusely 5-lobed. Corolla 20–45 x 10–18mm, most commonly dark red, at least at higher altitudes, sometimes pink or cream, rarely greenish or white; tube 15–25 x 4–7 x 6–10mm, curved or straight, at first densely covered with golden-brown stellate scales outside, completely glabrous inside; lobes 7–12 x 6–11mm, spreading perpendicularly, sub-circular, overlapping ½–2⁄3, scaly on the proximal part outside. Stamens unequal, clustered on the upper side of the mouth, slightly exserted to c.5mm; filaments linear, red, glabrous or rarely with a few hairs; anthers 2–2.5 x c.1.2mm, obovate-oblong, brown to dark red. Disc low, without simple hairs but sometimes with a few scales. Ovary 6–8 x 2.5–3mm, elongate-conical or sub-ovoid, densely stellate-scaly, usually abruptly tapering distally; style thick, as long as the stamens and exclusively stellate-scaly to the top at flowering, but becoming glabrescent distally as the fruit develops; stigma broadly obconical, slightly 5-lobed. Fruit 20–40 x 5–6mm, thick-fusiform, often a little wider in the distal ½, longitudinally grooved, densely brown scaly, usually with the persistent remains of the style. Seeds 2–4mm, without tails to 1.2mm, the longest tail c.1.5mm.

Habitat: Predominantly terrestrial but also epiphytic in mossy forest and on tree-ferns in grassland.

Distribution: Indonesia, New Guinea (W), along the Main Range from the Wissel Lakes. Papua New Guinea, main range east to Mt Vict­oria and Mt Dayman; also on Mt Saruwaged and Bismarck Mts.

Altitude: 1400-4000m

Notes

Named after M.W. Beyerinck, 1851–1931, a Dutch microbiologist.

A widely distributed species, both altitudinally and geographically. Sleumer (1966) conceived this species in a broad sense and acknowledged that it might ultimately be united with R. phaeochitum. For differences between this species and R. phaeochitum see under that species. Van Royen & Kores (1982) reported that it had been found on all major mountain ranges from the Nassau Mts to Mt Dayman and that ‘it is an extremely polymorphic species. Plants from different geographic locations vary considerably in stature, flower color, leaf size, leaf shape and texture. In addition the species also appears to vary throughout its altitudinal range’. Specimens of Rhododendron beyerinckianum obtained from lower altitudes tend to be larger, more robust than high altitude collections, their leaves are larger, less leathery and the indumentum is poorly to moderately well developed. Material from higher altitude tends to be more compacted than low altitude material, the leaves are smaller, more leathery, frequently somewhat revolute and the indumentum is generally very well developed’.

Nomenclature

Type: von Römer 1199, Aug. 1876. W New Guinea, Hellwig Mts, Mt Agathodaemon (BO, L).

Synonymy: R. schultzei Schltr., Bot. Jahr. 1918. 55: 154. R. dasylepis Schltr., Bot. Jahr. 1918. 55: 153, f.4. R. saavedranum Diels, Bot. Jahr. 1929. 62: 486. R. beyerinckianum var. longipetiolatum J.J.Sm., Nova Guinea 1936. 18: 94. R. chrysopeplon Sleumer, Bot. Jahr. 1949. 74: 540.

Flags

Occurs in Countries: ID, PG Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Vireya Habit: Epiphyte, Tree Fl. Colour: cream, green, pink, red, white

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:75

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Rhododendron bicorniculatum P.X.Tan

Shrub aim, young shoots densely covered with reddish-brown strigose hairs. Leaves dimorphic, coriaceous; spring leaves obovate to obovate-elliptic 3.5-5 x 1.5cm, 2.2-2.6(-3.3) x as long as broad, apex shortly acuminate, margin revolute, base cuneate, upper surface sparsely strigose at first, becoming glabrescent, lower surface pale, adpressed reddish-brown-strigose, especially on midrib; summer leaves spathulate-ovate, 15-20 x 7-9mm, otherwise as for spring leaves; petioles short. Inflorescence 2-4-ftowered; pedicels c.5mm, densely reddish-brown-strigose. Calyx strigose, minute. Corolla funnel-campanulate, reddish purple, 18mm; tube c.5mm. Stamens 5, pubescent below, anthers with apical projections. Ovary strigose; style glabrous. Fruit cylindrical, strigose, 12-13 x 3-4mm.

Habitat: By streams

Distribution: China (Guangdong)

Notes

Close to R. naamkwanense but differing in its larger leaves, 4-flowered inflorescence, and in the form of the anthers.

Nomenclature

Type: China, Guangdong, Conghua Xian, Rhu-Tin, in rivulo, prope vallem, 16 iii 1973, S.Q. Chen (S.H.Chun) 18489 (holo. IBSC)

Flags

Occurs in Countries: CN Subgenus: Tsutsusi Habit: Non-Tree Fl. Colour: purple, red

Chamberlain, D.F. & Rae, S.J. (1990) A Revision of Rhododendron IV Subgenus Tsutsusi. Edinburgh Journal of Botany 47(2):133

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Rhododendron blackii Sleumer

Shrub to 3m. Twigs 3–4mm in diameter, rounded, sub-densely scaly, longitudinally striate when dry; internodes 5–13cm. Leaves in tight pseudowhorls of 3–4, but inserted over 1–2cm. Blade 40–75 x 30–65mm, ovate to circular, rarely obovate; apex obtuse to rounded; margin cartilaginous, entire, narrowly revolute; base auriculate, the sides broadly turned down; laxly silvery scaly above, quickly becoming glabrescent; below laxly to sub-densely and more persistently scaly. Scales sub-circular to broadly sub-stellately lobed; the marginal flange broad, thin and transparent, the centres moderately small and impressed. Mid-vein raised above in the proximal 1⁄3–½, then impressed, grooved where it is raised; below raised throughout its length but decreasing distally; lateral veins 5–7 per side, wide-spreading, above slightly raised and minutely grooved, beneath very slightly raised; straight but branching and anastomosing before the margin. Petiole 2–4 x 2–4mm, sometimes grooved above distally, scaly. Bracts to 18 x 12mm, the outermost scaly outside, inner ones with scales on the margins, shortly hairy outside and minutely hairy inside. Inflorescence of 5–9 flowers in an open umbel. Flowers 60–65 x 35–40mm. Pedicels 30–35 x c.1mm, densely scaly. Calyx c.4mm in diameter, disc-shaped, densely scaly and fringed on the margin with scales. Corolla red; tube 40–62 x 5–6 x 12–27mm, sub-densely scaly outside, densely hairy with irregular or somewhat retrorse hairs inside; lobes 15–23 x 12–21mm, reflexed, overlapping to c.halfway, scaly outside except near the margins. Stamens exserted to c.12mm, clustered on the upper side of the mouth; filaments hairy in the proximal ½–2⁄3, glabrous distally; anthers c.3mm, curved. Disc densely hairy on the upper side, otherwise glabrous. Ovary c.8 x 3mm, elongate-conical, densely hairy and scaly, tapering gradually distally; style c.45 x 1mm, densely hairy and scaly for the proximal 3–5mm, then glabrous distally, purplish-red; stigma c.4mm in diameter, rounded, yellow. Fruit 28–38 x 6–7mm, fusiform, longitudinally grooved, pale brown.

Habitat: Epiphytic in mixed montane forest, secondary forest with climbing bamboo, or terrestrial at forest margins and in fire-induced grassland with Gleichenia.

Distribution: Papua New Guinea, Western Highlands between Laiagam and Kandep, c.4 miles W of Wabag; Southern Highlands, Mt Ambua, Mt Hagen, Mt Kerewa, Mt Giluwe, Ibiwara (Tari Gap).

Altitude: 2500-3300m

Notes

Named after Michael Black, an English medical doctor who collected in New Guinea and grew vireya rhododendrons at his home in Grasmere.

Nomenclature

Type: Vink 17280, 28 July 1966. New Guinea (E), Southern Highlands District, Tari subdistrict, Mt Ambua, 3390m (LAE, L, K).

Synonymy: R. sleumeri A.Gilli, Ann. Naturh. Mus. Wien 1980. 83: 435.

Flags

Occurs in Countries: PG Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Vireya Habit: Epiphyte, Non-Tree

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:310

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Rhododendron bloembergenii Sleumer

Tree to c.3m. Twigs 4–9mm in diameter, sub-angular, sparsely appressed-scaly when young, becoming glabrescent and often whitish; internodes 5–20cm. Leaves 2–3 together in loose pseudowhorls with additional leaves on the internode. Blade 90–190 x 30–48mm, broadly elliptic; apex shortly and abruptly acuminate, sub-acute; margin narrowly revolute when dry; base broadly tapering, often unequal; sparsely scaly to glabrescent above, sub-persistently laxly to sub-densely scaly beneath. Scales minute, flat, the broad marginal zone irregularly sub- stellately lobed and breaking up early; centre small, hardly impressed. Mid-vein as wide as the petiole proximally, flat or shallowly impressed above, thick and obtusely prominent beneath; lateral veins 9–12 per side, high- ascending, at an acute angle, curved and anastomosing before the margin, with several intermediate smaller veins, all parallel, faintly impressed or raised above, distinctly prominent beneath, reticulation slightly raised beneath only. Petiole 10–20 x c.3mm, flattened, scaly, striate lengthwise. Bracts to 60 x 25mm, outer bracts 15–20 x 10mm, ovate, obtuse, initially hairy outside especially at the base, later glabrescent, distinctly rough to the touch, inner bracts elliptic to spathulate, very densely hairy outside. Bracteoles c.20 x 1–1.5mm, linear to sub-spathulate, densely hairy. Inflorescence c.10-flowered in a complete umbel. Pedicels 12–17 x 1.5mm, sub-densely sub-stellate-scaly. Calyx c.3mm in diameter, disc-like, short. Corolla 65–75mm, tubular below, expanded distally, white, scented; tube 45–50 x 5–6 x 6–7mm, cylindrical, straight, the base lobed, glabrous outside, densely shortly hairy inside; lobes 20–25 x 15–20mm, broadly obovate-spathulate or sub- circular. Stamens exserted to c.10mm; filaments linear and densely patently hairy in the proximal 2⁄3, glabrous and filiform distally; anthers 6–7 x 1.5mm, oblong, each cell contracted into a short basal apiculus. Disc prominent, glabrous. Ovary 9–10 x 3–4mm, sub-cylindrical, yellowish hairy (scales not visible), tapering distally; style thick, slightly exceeding the stamens, densely hairy proximally, sub-densely or laxly so and minutely scaly distally, glabrous for the terminal 6–8mm; stigma c.3mm in diameter, thick-knob-like. Fruit 35–40 x 7–8mm, thickly fusiform-cylindric, laxly shortly hairy, somewhat rugose, slightly curved.

Habitat: Summit vegetation

Distribution: Indonesia, Sulawesi, Ngilalaki, E of Lake Lindu; Latimodjong Mts.

Altitude: 2200-2335m

Notes

Named after the collector, Siebe Bloembergen, a Dutch botanist who worked in Indonesia.

Nomenclature

Type: Bloembergen 3972, 9 July 1939. Indonesia, Celebes, Central, E of Lake Lindu, towards the top of G. Ngilalaki, 2335m (BO, A, L).

Flags

Occurs in Countries: ID Altitude Ranges: 2,000 - 3,000m Subgenus: Vireya Habit: Tree Fl. Colour: white

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:288

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Rhododendron boninense Nakai

Much-branched shrub, to 2m; young shoots covered with adpressed rufous hairs. Leaves persistent, monomorphic, oblong-lanceolate, 2-5 x l-2cm, apex subacute, mucronuiate, base cuneate, upper surface sparsely covered with adpressed straight rufous hairs, lower surface with impressed veins and densely covered with adpressed straight rufous hairs; petioles 5~-10mm, channelled above, indumentum as for leaves. Inflorescence 4-6~flowered; pedicels 4-6mm, covered with adpressed rufous hairs and subtended by the sub-persistent bud-scales. Calyx with 5 minute acute or rounded teeth covered with adpressed rufous hairs. Corolla funnel-campanulate, white, 40-50mm long and as wide. Stamens 10, papillose below middle. Ovary densely covered with adpressed strigose hairs; style pilose below middle. Capsule 10~20mm, oblong-ovoid, covered with grey-brown hairs.

Habitat: Cliffs

Distribution: Japan (Bonin Islands)

Illustrations:

Notes

This is the only Rhododendron found in the Bonin Islands. It grows on the cliffy summit of Tsutsyiyama. The foliage resembles that of R. simsii and the flowers those of R. mucronatum.

Nomenclature

Type: Japan, Bonin Islands, T. Nakai & H. Toyoshima, n.v.

Flags

Occurs in Countries: JP Subgenus: Tsutsusi Habit: Non-Tree Fl. Colour: white

Chamberlain, D.F. & Rae, S.J. (1990) A Revision of Rhododendron IV Subgenus Tsutsusi. Edinburgh Journal of Botany 47(2):118

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Rhododendron bonvalotii Bureau & Franchet

Shrub; young shoots glabrous. Leaves elliptic, 4-5 x c. 1.5cm, 2.6-3.5 x as long as broad, apex acute, base rounded, upper surface glabrous, lower surface glabrous, mammillate, eglandular, veins not raised; petioles c.0.5cm, densely and shortly stipitate-glandular. Calyx c.4mm, densely glandular, lobes rounded, irregular. Corolla probably open-campanulate and pale pink, 22-25mm. Ovary glandular; style glandular to tip. Capsule not known.

Distribution: China (C Sichuan)

Notes

Only known from the poor isotype cited above. The leaves and glandular style suggest an affinity with R. cerasinum. There is also a (less likely) possibility that R. bonvalotii is a hybrid of R. souliei (subsection Campylocarpa); further material is required before a firm decision can be made.

Nomenclature

Type: China, Sichuan, autour de Tatsien lou, Bonvalot (iso. E).

Flags

Occurs in Countries: CN Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: pink

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):418

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Rhododendron boothii Nuttall

Usually an epiphytic shrub, rarely on rocks, up to 2 m. Young growth with a dense indumentum of twisted and matted loriform setae. Leaves narrowly ovate to ovate-oblong, acuminate at the apex, rounded at the base, very hard and leathery, 78-112 x 38-52 mm, upper surface with dense, matted loriform setae on the midrib (and rarely secondary veins), margin loriform-ciliate, lower surface with dark brown, close, ± equal scales. Inflorescence (3-)4-6(-10)-flowered, pedicels stout, up to 15 mm, covered with matted loriform setae. Calyx lobes green, ovate to oblong, (7-) 10-15 mm, lepidote and loriform-ciliate. Corolla campanulate, dull to bright yellow, sometimes spotted, 25-27 mm, tube 15-16 mm, lepidote on the lobes and tube outside, pilose within the tube. Ovary lepidote. Capsule ± ovoid, up to 15 mm

Habitat: Forests and scrub

Distribution: India (Arunachal Pradesh), China (S Xizang)

Altitude: 1800-2450m

Illustrations:

Notes

I have seen no material with more than six flowers in the inflorescence, though the illustration in the Botanical Magazine, t. 7149, shows such a plant

Nomenclature

Type: Bhutan'(i.e. India, Arunachal Pradesh, cf. Ludlow, Trans. Bot. Soc. Edinb. 41:359, 1972), Gescherong Hills, Booth (holo. K)

Synonymy: R. mishmiense Hutchinson & Kingdon Ward, Notes R.B.G. Edinb. 16:173 (1931). Type: Assam, Mishmi hills, Delei valley, 7-8000 ft, Kingdon Ward 8046 (holo. E)

Flags

Occurs in Countries: CN, IN Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: yellow

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):134

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Rhododendron borneense (J.J.Sm.) Argent, A.Lamb & Phillipps

Notes

Latin – borneense – from Borneo, indicating the island of origin.

Nomenclature

Type: Endert 4256, 17 Oct. 1925. Borneo, Central East, W Kutei, Mt Kemul (BO, A, L).

Synonymy: R. quadrasianum S.Vidal var. borneense J.J.Sm., Bull. Jard. Bot. Buit. III, 1935. 13: 444.

Flags

Occurs in Countries: ID, MY Altitude Ranges: 1,000 - 2,000m Subgenus: Vireya Fl. Colour: red, white, yellow

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:44

Rhododendron borneense subsp. angustissimum (J.J.Sm.) Argent, A.Lamb & Phillipps

Shrub to 2m. Twigs shortly hairy. Leaves spiral. Blade c.10 x 1–1.5mm, narrowly obovate to almost linear, densely spirally arranged especially towards the tips of the young shoots. Pedicels slender, c.5mm, hairy. Calyx both hairy and ciliate on the margins, lobes very short. Corolla c.10 x 3–4mm, tubular, slightly dilated distally, red, densely covered with round scales and sparse long white hairs. Stamens exserted; anthers 0.5mm. Ovary hairy.

Habitat: Epiphytic in sub-montane forest, or terrestrial in open peaty locations, locally abundant.

Distribution: Malaysia (Borneo), Sarawak, Mt Mulu.

Altitude: Around 1300m

Notes

Latin – angusti – narrow; issimum – the superlative. The most narrow leaved.

Flowers June

This is an extreme form of R. borneense which approaches R. ericoides in the size of its leaves.

Nomenclature

Type: Anderson 4215, 28 June 1961. Borneo, Sarawak, Mt Mulu, path from Melinau Paku (SAR, K, L, fragment).

Rhododendron borneense subsp. borneense

Shrub to 2m. Twigs rounded, shortly hairy and scaly, quickly glabrescent, older stems rough with raised leaf scars. Leaves arranged spirally but mostly only persisting at the very ends of the twigs. Blade 14–18 x 5–8mm, obovate or spathulate; apex rounded or slightly retuse; margin entire, slightly revolute; base tapering, sparsely scaly and quickly glabrescent above, sparsely but persistently scaly below and sometimes with a few short hairs near the base. Scales round, slightly impressed. Mid-vein slightly impressed above and raised below, the lateral veins weak, up to 3 per side, not raised or impressed, sometimes not visible. Petiole 2–3 x c.1mm, weakly grooved above, scaly and often shortly hairy. Flower buds to 6 x 2mm, slender, ellipsoid, with scattered scales outside and a distinct fringe of hairs around the bract margins. Bracts ovate to spathulate. Bracteoles 3.5 x c.0.5mm, narrowly spathulate, with a few hairs near the apex. Inflorescence of mostly solitary flowers, occasionally 2 or 3 together, horizontal to half-hanging. Pedicels 6–8 x c.1mm, hairy and scaly, pink. Calyx a low hairy and scaly disc. Corolla 20 x 10mm, red or yellow, without scent; tube 15 x 6 x 8mm, straight, lobed near the base, densely scaly and with white erect hairs at least in the proximal ½ outside, glabrous inside; lobes 4 x 5mm, erect, or slightly spreading, overlapping for about ½ their length, scaly outside, rarely with a few simple hairs. Stamens loosely arranged on the lower side of the mouth, exserted to c.4mm; filaments c.18mm, glabrous; anthers 7mm, brown. Ovary c.2 x 1mm, densely sub- patently hairy and with a few scales; style 13–16mm, entirely glabrous or hairy in the proximal ½, slightly swollen distally, lying on the lower side of the tube; stigma exserted to c.5mm, club-shaped, purple, 0.75mm in diameter. Fruit c.8 x 3mm. Seeds 1.6mm, without tails 0.7mm, the longest tail 0.6mm.

Habitat: Mostly epiphytic in montane forest.

Distribution: Indonesia, Kalimantan. Malaysia (Borneo), Sarawak and Sabah. Brunei. Widespread on the mountains of Borneo, said to be common on Mt Kemul, but only recorded in Sabah from Mt Lotung in the south.

Rhododendron borneense subsp. villosum (J.J.Sm.) Argent, A.Lamb & Phillipps

Shrub to 3m. Leaves 8–13 x 2–4mm, narrowly obovate. Corolla hairy (sometimes only sparsely so), and scaly, red or yellow, c.15mm. Pedicels scaly and hairy. Ovary scaly and densely white-hairy.

Habitat: Mostly epiphytic in sub-montane mossy forest, low shrubby kerangas and amongst bare sandstone rocks

Distribution: Malaysia (Borneo), Sabah, northern in distribution, from Mt Kinabalu, along the Crocker Range, to Mt Lotung. Sarawak, Mt Murud, Mt Dulit and Mt Tanggoi. Brunei, Mt Pagon.

Altitude: 1200-1900m

Notes

Latin – villosum – with long soft hairs, presumably alluding to the hairs on the twigs, pedicels and flowers.

Flowers Jan.–Dec

Leaves consistently smaller than in ssp. borneense but larger than in ssp. angustissimum.

Nomenclature

Type: Hallier 575, 1893–94. Borneo (W), Mt Damus, Upper Sambas River (BO, CAL, K, L, P, U).

Synonymy: R. quadrasianum S.Vidal var. villosum J.J.Sm., Bull. Jard. Bot. Buit. III, 1935. 13: 444.

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Rhododendron brachyanthum Franchet

Shrub to 2 m. Leaves narrowly elliptic to narrowly obovate, acute to rounded at the apex, cuneate at the base, 35-55 X 12-20(-23) mm, upper surface dark green, lower surface with scales more than 2 x their own diameter apart, the smaller scales clear or milky. Inflorescence 3-7(-10)-flowered, pedicels lepidote, 12-25(-30) mm, rachis distinct, more than 4 mm, lepidote or very rarely minutely puberulent. Calyx lobes rounded at the apex, slightly glaucous, lepidote at the base and sometimes around the margin. Corolla campanulate, pale or greenish yellow, 10-20 mm, tube 6-11 mm, elepidote or sparsely lepidote outside. Capsule ± globose or ovoid-globose, c. 8 mm.

Notes

The species varies in the density of scales on the lower leaf surface; two subspecies are distinguishable

Flags

Occurs in Countries: CN, MM Altitude Ranges: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: green, yellow

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):144

Rhododendron brachyanthum subsp. brachyanthum

Habitat: Scrub and thickets

Distribution: China (C Yunnan)

Altitude: 3050-3350m

Illustrations:

  • Gard. Chron. 70:7 (1921)
  • Miilais, Rhododendrons, ser. 2, opp. p. 168 (1924)
Notes

Subsp. brachyanthum is entirely restricted to the area around Tali, and is separated from the much more widespread subsp. hypolepidotum by about 160 km.

Nomenclature

Type: China, Yunnan, in monte Tsang chan pro-pe Tali, Delavay 159 (holo. P—n.v., iso. E)

Rhododendron brachyanthum subsp. hypolepidotum (Franchet) Cullen

Habitat: Dry, open situations in forest and scrub, rarely epiphytic

Distribution: NE Burma, China (NW Yunnan, SE Xizang)

Altitude: 3050-4000m

Illustrations:

  • Millais, Rhododendrons, ser. 2, opp. p. 168 (1924)
  • Bot. Mag. 155: t. 9259 (1931-2)
  • Ic. Corm. Sin. 3: t. 4004 (1974)
Notes

Subsp. hypolepidotum is much more widespread than subsp. brachyanthum and much more variable, particularly in the density of the scales on the lower leaf surface. Some specimens have very abundant darker scales, whereas others have these very distant, though the yellow scales may be fairly close. In general, the closer the yellow scales, the more likely they are to have the milky appearance characteristic of those of R. pruniflorum.

Nomenclature

Synonymy: R. brachyanthum var. hypolepidotum Franchet, Journ. de Bot. 12:262 (1898). Type: China, Yunnan, Tsekou, Se la, Soulie 1027 (holo. P—n.v., iso. E). R. hypolepidotum (Franchet) Balfour f. & Forrest, Notes R.B.G. Edinb. 13:266(1922). R. charitostreptum Balfour f. & Kingdon Ward, Notes R.B.G. Edinb. 13:244 (1922). Type: NE Upper Burma, Imaw Bum, 11-12000 ft, 2 vii 1919, Kingdon Ward 3302 (holo. E)

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Rhododendron brachycarpum [D. Don ex] G. Don

Shrub, 2-3m; young shoots tomentose, soon glabrescent. Leaves oblong to obovate,7-ll x 3-4.5cm, 2.3-2.5 (-3) x as long as broad, apex ± rounded, apiculate, base rounded, upper surface glabrous, lower surface glabrous or with a compacted greyish to fawn indumentum; petioles l-2cm, glabrous, with lamina slightly decurrent. Inflorescence lax, 10-20-flowered; rhachis 20-40mm; pedicels c.30mm, sparsely tomentose. Calyx c.2mm, tomentose, lobes glabrous. Corolla broadly funnel-campanulate, white to pale rose-pink, with greenish flecks, c.25mm. Ovary densely tomentose; style c.l5mm, glabrous. Capsule 20-30mm long.

Notes

Subsp. tigerstedii, from mainland Korea and the offshore Dagelet Island, is described as differing from subsp. brachycarpum in its larger leaves, 15-25cm long, and in its large white flowers (c. 70mm in diam.), etc. I have not seen sufficient wild-collected material of subsp. tigerstedtii to confirm the constancy of these differences, but from the description, the distinctions made appear to be relatively trivial.

Flags

Occurs in Countries: JP Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: green, rose, white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):307

Rhododendron brachycarpum subsp. brachycarpum

Leaves with a compacted grey to fawn indumentum beneath, even when mature

Distribution: Japan, E Korea

Notes

Described from Japan

See also Doleshy (1968)—ref. p. 305

Nomenclature

Synonymy: R. brachycarpum G. Don var. roseum Koidzumi, Bot. Mag. (Tokyo) 30: 77 (1916). Type: Japan, in alpis Yeso, n.v. R. faurieiFranchet var. rufescensNakai, Trees Shrubs Japan, ed. 2,1: 56 (1927). Type: uncertain. 1R. brachycarpum G. Don subsp. tigerstedtii Nitzelius, Deutsche Baum- schule no. 7: 207 (1970). Type: a specimen from a cultivated plant grown in Mustila, Finland, originating from Kongo San in E C Korea (nolo. GB, n.v.)

Rhododendron brachycarpum subsp. fauriei (Franchet) Chamberlain

Leaves ± glabrous beneath when mature

Distribution: Japan, Korea

Illustrations:

  • Nakai, Fl. Sylva Koreana 8, t. (1919) - as R. brachycarpum
Notes

Ohwi (Fl. Japan, English Version, 698,1965) implies that R. brachycarpum of G. Don has entirely glabrous leaves and that R. fauriei is synonymous with it. However, Don clearly states that the leaves of R. brachycarpum have an indumentum on the lower surface. The synonymy cited here follows from the correction of this error. Nakai (loc. cit.) implies that all the material from Korea has glabrous leaves which is not entirely true. However, most of the Korean material seen is referable to subsp. fauriei which does appear to have a wider range than does the type subspecies. R. hidaense Makino (in Hara, Enum. PL Japon. 1: 33 (1948)-Type: Japan, Prov. Hida, in silva Aoya, vii 1939, Makino, n.v.) is probably a hybrid between this and the next species (see Hara, loc. cit.).

Nomenclature

Synonymy: R. fauriei Franchet, Bull. Soc. Philom. Paris ser. 7, 10:145 (1886). Type: Nippon septentrionalis, in monte Schichinake, prope Aomori, 21 vi 1886, Faurie 758 (iso. E, K). R. brachycarpum G. Don var. roseiflorum Miyoshi, J. Coll. Sci. Imp. Univ. Tokyo 27: 8 (1910), no type designated.

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Rhododendron brachygynum H.F.Copel.

Shrub to 1m. Twigs red-brown. Leaves either in pseudowhorls at the end of the branchlets or scattered and spiral. Blade c.100 x 45mm, elliptic; apex shortly acuminate; base obtuse, decurrent into the petiole, shining and minutely blackish pitted above, sparsely covered with pale scales beneath. Petiole 15mm. Inflorescence 5-flowered. Pedicels c.20mm, strong, hairy. Corolla 40mm, narrowly obconical, yellow; lobes c.15mm, rounded. Stamens c.30mm; filaments minutely hairy in the proximal part; anthers c.3mm, oblong, base minutely appendaged. Disc hairy, at the upper margin. Ovary c.8 x 3mm, sub-cylindrical, densely hairy, abruptly contracted distally; style c.9mm, glabrous; stigma 2mm in diameter, rounded.

Distribution: Philippines, Cebu

Notes

Greek – brachus – short; gynum – ovary. Alluding to the very short pistil.

Once found.

This species is based on a single specimen that has since been destroyed; Sleumer saw no material. The description here is modified from Sleumer’s translation of the original Latin. Copeland in discussing this species (1929) regarded it as related to R. teysmannii (R. javanicum ssp. teysmannii) and R. kochii. It would appear to belong to the R. javanicum complex but it is clearly distinct from R. kochii in both flower colour and leaf shape. Copeland also states: ‘On the other hand this species represents a transition from the ones just mentioned to R. leytense and R. loheri, which share the yellow flowers and appendaged anthers, but have somewhat smaller leaves, not at all acuminate, and drying to a dark brown colour. All the species here mentioned are alike in the hairiness of the ovary and filaments. Rhododendron brachygynum differs from all the others in the fact that the pistil is only about half as long as the stamens’.

The status of this species will not be satisfactorily evaluated without further collections from the type locality. It probably will turn out to be a minor variant of R. leytense (itself very similar to the R. javanicum complex). The very short pistil, the character to which Copeland appears to give most significance, may well be the result of examining very young flowers. The style elongates substantially in many species as flowers age and pass from the early unreceptive stigma phase to the later receptive one.

Nomenclature

Type: Sudlon, Cenabre & De la Cruz F.B. 28346. Philippines, Cebu (PNH†).

Flags

Occurs in Countries: PH Subgenus: Vireya Habit: Non-Tree Fl. Colour: yellow

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:282

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Rhododendron brachypodarium Sleumer

Shrub to 3m. Twigs 2–3mm in diameter, densely scaly, greyish often whitish when dry; internodes 2–10cm. Leaves reflexed, 4–5 together in tight pseudowhorls. Blade 40–80 x 20–40mm, elliptic, obovate-elliptic to obovate; apex broadly tapering, obtuse or rounded; margin entire, wavy, flat or only slightly and narrowly revolute; base more broadly to narrowly tapering; sub-densely scaly on both sides initially, early glabrescent above, more slowly so beneath. Scales flat, marginal zone angular or dentate; centre small, slightly impressed. Mid-vein thick, grooved and strongly raised in the proximal ¼–1⁄3, then smooth or impressed above, beneath, strongly raised and gradually tapering throughout its length; lateral veins 7–10 per side, issuing at c.45°, almost smooth often obscure, reticulation obscure. Petiole 6–12 x 1.5–2mm, weakly grooved above, densely scaly initially. Bracts to 20 x 13mm, green when fresh, outer ones ovate, firm, scaly at apex and margin, fringed with scales, inner ones thinner, broadly spathulate, very laxly hairy in the proximal part on both sides, otherwise glabrous. Bracteoles to 18mm, filiform, laxly hairy. Inflorescence an 8–14-flowered open umbel. Pedicels 4–8 x 0.5mm, densely scaly. Calyx c.2mm in diameter, oblique, rim-like, obscurely lobed, scaly outside. Corolla narrowly trumpet-shaped, pure white, scented, 40–50mm; tube 23–40 x 2–2.5 x 2.5–3mm, straight or curved, densely stellately scaly outside, shortly hairy inside; lobes 10 x 4–5mm, spreading becoming strongly reflexed, obovate, not or hardly overlapping. Stamens irregularly centrally grouped, exserted to c.10mm; filaments narrowly linear and densely hairy in the proximal ¾, slender and glabrous distally; anthers 3–4mm, narrowly oblong, base obtuse. Disc slightly prominent, laxly short-hairy. Ovary c.8 x 1.3mm, narrowly cylindrical, dense white or yellowish hairs covering scales, tapering distally; style exserted from the mouth for c.5mm, densely hairy at the base, then more laxly hairy and densely scaly, exclusively scaly for the distal 1⁄3; stigma obconical, green.

Habitat: Epiphytic or terrestrial in Castanopsis and Nothofagus forests, also on mossy ridges and valley forest.

Distribution: Indonesia, New Guinea (W), Vogelkop Peninsula, Tamrau, Tohkiri and Nettoti Range.

Altitude: 1200-2000m

Notes

Greek – brachypodus – short stalked, alluding to the short-stalked flowers.

A distinctive species with extremely narrow flowers (amongst the New Guinea species of this group) reminiscent of R. jasminiflorum. The flowers were recorded in the field as becoming fragrant towards the evening.

Nomenclature

Type: van Royen & Sleumer 7065, 26 Oct. 1961. New Guinea (NW), Tohkiri Mts, East crest 1400m, on path Surerem–Chaquai (L, A, BO, CANB, G, K, LAE, UC).

Flags

Occurs in Countries: ID Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Vireya Habit: Epiphyte, Non-Tree Fl. Colour: white

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:171

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Rhododendron bracteatum Rehder & Wilson

Shrub to 2 m with thin lepidote branches. Young shoots purplish, puberulous. Leaves ovate to elliptic, up to 35 x 15 mm, ± acute at the apex, rounded to subcuneate at the base, ± glabrous and elepidote above, sparsely lepidote with large, golden scales beneath. Bud scales of the leaf buds persistent. Inflorescence 4-6-flowered, pedicels sparsely lepidote, puberulous at the base. Calyx weakly 5-lobed, the lobes 1-2 mm, sparsely lepidote, the margins filiform-acicular-ciliate. Corolla openly funnel-shaped, 15-25 mm, white with many reddish spots, sparsely lepidote and puberulent towards the sinuses outside, puberulent inside the tube. Stamens 10, filaments pubescent towards the base. Ovary lepidote and sparsely puberulent towards the apex. Style shorter than the longest stamens at anthesis, glabrous or sparsely pilose at the base. Capsule lepidote, 10-15 mm.

Habitat: In woodland and on cliffs,

Distribution: China (C Sichuan)

Altitude: Around 3300m

Illustrations:

Nomenclature

Type: China, W Szechuan, near Wen chuan hsien, 3300 m, vii 1908, Wilson 3421 (iso. K)

Flags

Occurs in Countries: CN Altitude Ranges: 3,000 - 4,000m Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: red, white

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):88

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Rhododendron brassii Sleumer

Erect shrub to 2.5m. Twigs rounded, reddish and often whitish, when dry, smooth, tips laxly to densely covered with small, flat, sub-stellate scales; internodes 5–16cm, often with conspicuous broad hemispherical to rounded buds in the leaf axils. Leaves spiral, equally spaced along the branches. Blade 30–50 x 15–25mm, elliptic, broadly elliptic or sub-obovate; apex broadly obtuse or rounded, apiculate with a thick prominent gland; margin flat or weakly revolute, entire or minutely irregular to denticulate-crenulate and narrowly cartilaginous; base broadly tapering and somewhat decurrent, more rarely almost rounded, laxly scaly above but quickly glabrescent, the scales leaving minute pits, more persistently brown-scaly beneath. Scales small, sub-circular, variously sub-­stellately lobed; centre small, slightly impressed. Mid-vein impressed above especially at the base and obtusely prominent beneath; lateral veins 6–8 per side, ascending at an angle of c.45°, slightly impressed above, raised or inconspicuous beneath, reticulation visible only beneath. Petiole 3–6 x 1.5–2mm, grooved above, flattened, scaly. Flower buds to 30 x 14mm, ovoid, smooth with the bracts fully appressed, green or flushed with purplish red. Bracts 20–30 x c.15mm, membranous, glabrous except for the fringe of scales on the margins, outer, ovate, obtuse or emarginate. Bracteoles c.20 x 1–1.5mm, linear, glabrous. Inflorescence 3–6-flowered, in an open or one-sided umbel, the flowers hanging vertically or sometimes half-hanging. Pedicels 20–25 x c.1.5mm, laxly sub-stellately scaly below, more densely so distally, without hairs. Calyx 4–5mm in diameter, very obliquely disc-shaped, shortly, obtusely, 5-lobed, scaly outside. Corolla 45–50 x 25–30mm, dull yellow or greenish-yellow with a strong red flush on the proximal ½ of the tube, without scent, narrowly funnel-shaped, fleshy, glabrous both in and outside; tube 30–38 x 6–7 x 10–15mm, almost straight; lobes 12–15 x 14–18mm, broadly rounded to ovate, spreading horizontally, overlapping to c.halfway. Stamens very un­equal, loosely clustered on the lower side of the mouth, exserted to c.10mm; filaments linear, glabrous, pale yellow; anthers 2.5–3 x 1.3–1.5mm; cells obovoid and basally apiculate. Disc green, prominent, glabrous. Ovary c.5 x 2.5mm, sub-ovoid-cylindrical, very densely covered with silvery sub-circular or angled, flat scales, gradually tapering distally; style slender, laxly scaly proximally for up to 10mm, glabrous distally, exserted up to 15mm from the corolla; stigma thick-capitate, green. Fruit 15 x 6mm, obliquely fusiform-cylindrical.

Habitat: Shrubby forest, or grassy margins of Podocarpus forest, or open shrubberies on ridges, locally plentiful

Distribution: Indonesia, New Guinea (W), near Lake Habbema and the Wamena R. on N slope of Mt Wilhelmina (Trichora).

Altitude: 3200-3225m

Notes

Named in honour of Leonard Brass, famous for his botanical collecting expeditions in New Guinea.

Sleumer (1973) notes under R. ultimum that it may not be specifically different from that species. In fact, in the field, the differences are very obvious: R. brassii grows at a lower altitude and is a tall, erect shrub with green or silvery-green leaves, whereas R. ultimum is at higher altitude and is a low, spreading shrub with purplish leaves. Both have been grown side by side in cultivation and retain their distinctive habits. A hybrid with R. versteegii (R. x nebulicola) has been described from the wild by Danet (2005).

Nomenclature

Type: Brass 9139, Aug. 1938. New Guinea (W), Lake Habbema, 3225m camp (A, BO, L).

Flags

Occurs in Countries: ID Altitude Ranges: 3,000 - 4,000m Subgenus: Vireya Habit: Non-Tree Fl. Colour: green, red, yellow

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:223

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Rhododendron brevinerve Chun & Fang

Small tree, 4-7m; young shoots glandular-setose. Leaves elliptic, 8.5—12 x 2.5-4cm, 2.4—4.3 x as long as broad, apex bluntly acuminate, base cuneate, lower surface glabrous though with numerous red sessile punctate glands; petioles l-3cm, glabrous at maturity. Inflorescence 2-3-flowered; rhachis c.3mm; pedicels 10-25mm, densely stipitate- to setose-glandular. Calyx 2-3.5mm, lobes rounded, stipitate-glandular, especially on margins. Corolla campanulate, purple, 35-40mm. Ovary densely long-stipitate-glandular; style glandular in lower half. Capsule 12-20 x 6-8mm.

Habitat: Forests

Distribution: China (Guizhou, Guangxi, Guangdong)

Altitude: 500-2000m

Notes

Closely allied to R. mengtszense, with which it shares a setose-glandular indumentum.

Nomenclature

Type: China, Guangxi, Lungsheng Hsien, Pingshui Hsiang, Taosan Chun, 6 ix 1955, Kwangfu Exped. 8, n.v.

Flags

Occurs in Countries: CN Altitude Ranges: 0 - 1,000m: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Hymenanthes Habit: Tree Fl. Colour: purple

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):292

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Rhododendron breviperulatum Hayata

Much-branched shrub; young shoots slender, covered with adpressed flattened shining brown hairs. Leaves persistent, chartaceous, ovate-elliptic, 1-3 x 0.6-1.7cm, 1.8-2.5 x as long as broad, apex obtuse and mucronate, margin entire, base broad, cuneate-rounded, both surfaces with scattered adpressed pilose shining brown hairs that turn grey, upper surface with impressed midrib, lower surface reticulate; petiole 2-5mm. Inflorescence 2-several-flowered; pedicels 3-5mm, covered with shiny flattened white hairs. Calyx 2-4mm, indumentum as for pedicels, 5-lobed. Corolla funnel-campanu-late, rose-pink with crimson spotting on upper lobes, 25mm. Stamens 5(-6), filaments pilose below middle, anthers apiculate at base. Ovary conic, densely pilose; style pilose at base, dilated at apex. Capsule not known.

Distribution: China (Taiwan)

Illustrations:

Notes

The plant in cultivation in Edinburgh has a low, spreading habit. In this it apparently matches the type specimen.

Nomenclature

Type: Taiwan, Nanto, Mt Pusasai, iv 1909, Mori, n.v. (nolo. TI)

Flags

Occurs in Countries: CN, TW Subgenus: Tsutsusi Habit: Non-Tree Fl. Colour: crimson, rose

Chamberlain, D.F. & Rae, S.J. (1990) A Revision of Rhododendron IV Subgenus Tsutsusi. Edinburgh Journal of Botany 47(2):124

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Rhododendron brevipes Sleumer

Shrub to 3m. Twigs 3–4mm in diameter, rounded or somewhat angled, at first sub-densely covered with flat, sub-stellate scales, later glabrescent; internodes 7–10cm. Leaves c.5 together in pseudowhorls at the upper 1–2 nodes, sub-sessile. Blade c.150 x 50–70mm, broadly elliptic to elliptic; apex shortly acuminate, sub-acute; margin flat; base broadly tapering, the extreme base sub-truncate-obtuse; upper surface glabrescent but densely, minutely, pitted; undersurface sub-densely scaly. Scales flat, thin, reddish-brown, the marginal area variously lobed; centre small, flat. Mid-vein as wide as the petiole at the base, narrowed upwards and slightly impressed above, prominent beneath; lateral veins 8–10 per side, with additional, less distinct ones between them; straight at the base, curved distally, indistinctly anastomosing along the margin, flat or faintly raised above, more distinct and raised beneath, reticulation visible above, almost obscure beneath. Petiole 1–2 x 3–4mm. Outer bracts to 20 x 10mm, ovate-acuminate, with a distinct, sharp point (3–4mm), very laxly scaly along the outer middle line or glabrous outside, densely scaly at the apex inside; inner bracts elliptic-sub-spathulate, glabrous, except scaly along the margins. Bracteoles c.20 x 1mm, filiform, sub-glabrous. Inflorescence a 6–7-flowered umbel. Pedicels 40–60 x c.1.5mm, dilated at the apex, laxly scaly, not hairy. Calyx to 3mm in diameter, oblique, a wavy rim. Corolla 75–80mm, funnel-shaped, tube yellow, lobes orange; tube 40 x 4–5 x 15mm, laxly to very laxly sub-stellately scaly outside, shortly hairy in the lower ¾ inside, straight; lobes c.40 x 25mm, obovate, spreading. Stamens unequal, the longest exserted to c.20mm; filaments linear and sub-densely hairy in the proximal ½, filiform and glabrous in the distal ½; anthers c.4 x 1.2mm, oblong, the base obtuse. Disc very prominent, white-hairy at the upper margin, glabrous below. Ovary 10–12 x 2–2.5mm, cylindrical, tapering distally, very densely scaly and laxly shortly white-hairy; style c.55mm, densely scaly and shortly hairy in the lower 2⁄3, more laxly scaly and without hairs to the apex; stigma thick, rounded, with 5 distinct, almost club-shaped lobes. Fruit cylindrical, scaly and hairy, c.80 x 3–4mm.

Distribution: Papua New Guinea, Western Highlands, Jimmy Valley, Karap village.

Altitude: Around 1725m

Notes

Latin – brevis – short; pes – foot. Alluding to the very short petioles.

One collection only.

A poorly known species very reminiscent of R. aurigeranum in that the tips of the bracts are scaly on both sides but this species has much shorter petioles.

Nomenclature

Type: Womersley & Millar NGF 7605. Papua New Guinea, Western Highlands, Jimmy Valley, near Karap (LAE).

Flags

Occurs in Countries: PG Altitude Ranges: 1,000 - 2,000m Subgenus: Vireya Habit: Non-Tree Fl. Colour: orange, yellow

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:318

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Rhododendron bryophilum Sleumer

Shrub to 2m. Twigs 1–2mm in diameter, slender, rounded, laxly leaved, the tips brown, at first densely covered with stellate scales, older parts glabrescent and rough with scale bases; internodes 2–8cm. Leaves 3–5 together in tight pseudowhorls. Blade 40–55 x 10–22mm, narrowly elliptic, widest in the middle; apex acute to obtuse; margin slightly revolute; base broadly tapering or sub-truncate-rounded, sub-densely scaly on both sides initially. Scales minute, deeply stellately divided and sub-dendroid, falling early, and becoming glabrescent, each on top of a persistent epidermal tubercle, which gives a rough texture. Mid-vein scaly for a long time, very slightly impressed above, prominent beneath; lateral veins 4–6 per side, curved and anastomosing, faintly visible on both sides. Petiole 2–3 x c.1mm, scaly, flattened. Bracts to 8 x 6mm, ovate to obovate-spathulate, apiculate or obtuse, membranous, glabrous, minutely fringed with scales. Bracteoles to 10mm, filiform, sub-­glabrous. Inflorescence a c.3-flowered open umbel. Pedicels 10–12 x 0.4mm, very slender, densely minutely stellate-scaly, without hairs. Calyx c.2mm in diameter, sub-oblique, small, obscurely 5-lobed, stellately scaly outside. Corolla 30–40mm, tubular, distinctly zygomorphic, pale pink, thin; tube 20–28 x 4–5 x 7–10mm, cylindrical, curved, glabrous outside, laxly hairy inside; lobes 10–12 x c.7mm, elliptic to spathulate, spreading and somewhat reflexed, not or only very slightly overlapping. Stamens exserted, 6–7mm, clustered on the upper side of the flower; filaments narrowly linear, glabrous at the base, then laxly hairy, but again glabrous distally; anthers 1.8–2 x 1mm, oblong. Disc very shortly hairy at the upper margin, glabrous elsewhere. Ovary c.4 x 1.5mm, elongate-ovoid, densely and exclusively stellate-scaly, gradually tapering distally; style c.18mm, relatively thick, laxly covered with short, sub-­patent hairs almost to the top; stigma shortly club-shaped.

Habitat: Epiphytic in tall forest

Distribution: Indonesia, New Guinea (W), Cycloop Mts.

Altitude: 1065-1830m

Notes

Greek – bryo – relating to moss; philos – loving. Alluding to the mossy branches on which this species was originally found growing.

Nomenclature

Type: Cheesman 51, March 1936. New Guinea (NW), Mt Cyclops (BM).

Flags

Occurs in Countries: ID Altitude Ranges: 1,000 - 2,000m Subgenus: Vireya Habit: Epiphyte, Non-Tree Fl. Colour: pink

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:77

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Rhododendron bullifolium Sleumer

Erect, few-stemmed shrub or small tree to 6m, the trunk 2–3m to 5cm in diameter. Twigs 3–10mm in diameter, rounded, covered with a persistent though fragile covering of reddish-brown stellate scales; internodes 6–25cm. Leaves 4–6 together in tight pseudowhorls. Blade 8–20 x 4.5–13cm, elliptic or ovate-elliptic, rarely broadly elliptic or ovate, slightly unequal sided; apex very shortly sub-acuminate, obtuse or rounded; margin flat; base rounded; young leaves thickly covered with stellate reddish-brown scales, mature ones glabrescent above, more persistently scaly beneath especially along the main veins. Scales dendroid, with the marginal zone deeply divided and the small centre deepened or prolonged downwards into a kind of foot. Mid-vein as wide as the petiole at the base, and hardly prominent there, becoming impressed distally above and raised below; lateral veins irregular, 10–14 per side, curved and anastomosing before the edge, impressed above, prominent beneath as are the smaller veins which are distinct and reticulate towards the leaf margin; dark green and glossy above, paler and dull beneath, deeply puckered in both the fresh and dry state. Petiole 25–50 x 2.5–3.5mm, densely stellate-scaly initially. Immature buds c.20 x 20mm, bracts ovate, the outer ones sub-acuminate, the inner ones obtuse, with long appressed hairs on both sides and scaly outside. Corolla (immature) densely scaly on the tube outside, glabrous at the lobes. Fruit pedicel densely scaly, c.25 x 1.5mm. Young fruit 25mm, fusiform, densely covered with scales and pale coarse hairs, as is the style, of which only the lower part (for c.3cm) is known. Twisted valves of the mature fruit 30–55mm.

Habitat: Undershrub or tree in transitional zone of Castanopsis to Nothofagus forest

Distribution: Indonesia, New Guinea (W), Arfak Mts, Mt Sarumot, Anggi Gigi Lake, once collected.

Altitude: 2050-2100m

Notes

Latin – bullatus – puckered; folium – leaf. Alluding to the leaves being deeply puckered.

Still apparently known only from the very imperfect type specimen and the collectors’ field notes.

Nomenclature

Type: Sleumer & Vink 4444, 26 Jan. 1961. Indonesia, W New Guinea, Arfak Mts, Mt Saru-mot near Iray, Anggi Gigi Lake (A, CANB, G, K, L, LAE, P, PNH, UC).

Flags

Occurs in Countries: ID Altitude Ranges: 2,000 - 3,000m Subgenus: Vireya Habit: Tree

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:77

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Rhododendron bulu Hutchinson

Erect, straggling shrub up to 1-6 m. Leaves (8-)12—21 X 4-7(-8) mm, elliptic or oblong-elliptic, apex rounded, obscurely mucronate, usually emarginate, base broadly cuneate, undersurface pale with tan speckling, with irregularly contiguous or slightly discontiguous colourless, straw or buff scales with some larger, darker scales dispersed among them. Inflorescence l-3(-5)-flowered, pedicel pubescent and lepidote, 1-2 mm. Calyx lobes l-2(-4) mm, triangular to irregularly rounded, outer surface lepidote, margin lepidote and with a few cilia. Corolla pinkish purple, magenta, deep violet or occasionally white, pubescent in the throat and rarely so on the outer surface, (9.5-)10.5-13(-17) mm, tube 2-5—3(—5) mm, lobes with pale scales on the outer surface. Stamens (8-)10. Ovary lepidote, style 12-17 mm, usually exceeding the stamens, usually pubescent and with a few scales towards the base. Capsule ovoid, lepidote, c. 5 mm.

Habitat: Open woodland, scrubby and wooded hillsides

Distribution: China (S Sl SW Xizang—Tsangpo valley)

Altitude: 3000-3800m

Notes

The Philipsons (1975, p. 47) record a natural hybrid with R. nivale subsp. nivate

Nomenclature

Type: SE Tibet Lusha, 3050 m, 19 v 1924, Kingdon Ward 5686 (holo. E)

Flags

Occurs in Countries: CN Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: magenta, purple, white

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):104

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Rhododendron bureavii Franchet

Shrub, l-3(-6)m. Leaves elliptic, 4.5-12 x 2-7cm, 1.7-3 X as long as broad, apex acuminate, base rounded or cuneate, lower surface with a dense unistrate lanate ramiform tomentum, salmon-pink when young, becoming rich rusty red; petioles l-2cm, densely tomentose. Inflorescence 10-20-flowered; rhachis 2-3mm; pedicels 10-20mm, densely pilose and glandular. Calyx 5-10mm, lobes fleshy or membranous, densely pilose and glandular. Corolla white flushed pink to pink, sometimes with purple flecks, 25-40mm. Ovary densely stipitate-glandular, sometimes also tomentose; style usually glandular, at least near the base. Capsule c.15 x 9mm.

Habitat: Open pine forests, Rhododendron thickets

Distribution: China (N Yunnan)

Altitude: 3350-4250m

Notes

R. cruentum is described as differing from R. bureavii in its smaller flowers and fleshy calyx. There is, however, a complete intergradation in these characters.

Nomenclature

Type: China, Yunnan, ad collum Yen-tze-hay, prope Lankong, 3200m, 1 v 1886, Detavay 2213 (iso. E, K).

Synonymy: R. cruentum Leveille, Feddes Repert. 12: 284 (1913). Type: China, Yunnan, brousse du plateau de Ta-Hai-Tse, 3200m, v 1912, Maire (holo. E)

Flags

Occurs in Countries: CN Altitude Ranges: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: pink, purple

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):338

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Rhododendron burjaticum Malyschev

Much branched spreading shrub to 15 cm. Leaves 8-12 x 3-6 mm, elliptic to ovate, apex obtuse, mucronate, base broadly cuneate, undersurface bicolorous, densely covered with pale golden scales mixed with darker, amber scales. Inflorescence 3-8-flowered, pedicel lepidote and minutely pubescent, (l-)2-3-5 mm. Calyx lobes rounded to triangular, c. 0-5 mm, lepidote, margin ciliate. Corolla rosy violet, narrowly funnel-shaped, 12-15 mm, tube 5-7 mm, pubescent in the throat. Stamens (5-)7(-10), shorter than corolla, filaments pubescent towards the base. Ovary lepidote, style 3-4 mm, shorter than the stamens. Capsule ovoid, lepidote, c. 6 mm.

Habitat: Moist places in Larch forests.

Distribution: USSR (eastern Sajan mountains to the west of the southern end of Lake Baikal)

Nomenclature

Type: USSR, Montes Sajanenses orientales, alpes Kito-jenses, fl. Saghan-Sajir, 20 vi 1958, Malyschev (holo. LE—n.v.)

Flags

Occurs in Countries: RU Subgenus: Rhododendron Habit: Non-Tree

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):106

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Rhododendron burmanicum Hutchinson

Shrub to 2 m. Young growth with a dense indumentum of loriform setae which is soon deciduous. Leaves obovate, tapering to the base, obtuse at the apex, 50-55 X 20-24 mm, upper surface dark green, rather densely lepidote with flat, somewhat dried-out scales, margins loriform-ciliate when young, somewhat crenate in the upper part, lower surface densely lepidote with overlapping to contiguous scales producing a brownish colour; petioles densely lepidote and sparsely loriform-setose. Inflorescence 4-6(-10)-flowered, pedicels densely lepidote. Calyx disc-like, undulate, lepidote, loriform-ciliate. Corolla greenish yellow, funnel-campanulate, 30-35 mm, tube 18-20 mm, the base of the tube pilose outside, the whole conspicuously lepidote, tube glabrous inside. Stamens 10, filaments densely pubescent in the lower part. Ovary densely lepidote; style impressed, lepidote in the lower part. Fruit unknown.

Habitat: Fringes of forest

Distribution: C Burma (Mt Victoria)

Altitude: 2700-2900m

Notes

Originally described from cultivated material, later refound in the wild. A distinct and easily recognised species.

Nomenclature

Type: a cultivated specimen (holo. K)

Flags

Occurs in Countries: MM Altitude Ranges: 2,000 - 3,000m Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: yellow

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):43

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Rhododendron burttii P.Woods

Shrub to 80cm. Twigs smooth, green or reddish, very finely hairy and laxly scaly. Leaves 5–8 in tight pseudo­whorls, with a variable number of smaller reduced scale leaves. Blade 18–28 x 9–12mm, obovate; apex broadly pointed to rounded; margin entire, slightly recurved; base tapering; laxly scaly above and with a few simple hairs but quickly glabrescent; below laxly and more persistently scaly but without hairs. Scales stellate, flat, with a broad marginal flange and small slightly impressed centre. Mid-vein impressed above, raised below; lateral veins 2–3 per side, faint or obscure. Petiole 4–5 x 1–2mm, hairy and scaly, weakly grooved at the junction with the lamina, green. Flower buds to 8 x 4mm, ellipsoidal, green, tips of the bracts stiffly erect, hairy outside and with marginal brown scales. Inflorescences often lateral as well as terminal, of 1–2 occasionally up to 4 flowers, hanging vertically. Pedicels 17 x 1mm, red, with long, white, spreading hairs. Calyx a low green disc with a hairy margin. Corolla 23 x 26mm, bright-red, without scent; tube c.17 x 8 x 6mm, swollen just above the base and then narrowed slightly, becoming parallel sided and straight, long-hairy and with a few scales outside, hairy only near the base inside; lobes 10 x 6mm, wide-spreading, not overlapping. Stamens spreading all round the mouth of the flower; filaments 18mm, white, passing to pink distally, broadened and hairy in the proximal 4mm; anthers 1.4 x 0.8mm, brown. Ovary c.4 x 3mm, shortly cylindrical, densely hairy, with white semi-appressed hairs and brown scales covered by the hairs; style 5 x 0.5mm, green with a few hairs near the base only; stigma green, 1mm in diameter. Fruit 16 x 5mm, cylindrical, white-hairy and with brown scales, the valves spreading widely after opening. Seeds 3.3mm, without tails 1mm, the longest tail 1.2mm.

Habitat: Epiphytic in mossy sub-montane forest.

Distribution: Malaysia (Borneo), Sarawak, Mt Murud, Mt Lawi. Sabah, Mt Lotung, Crocker Range and in the area of the River Rekong Waterfall near Long Pasia. Erroneously reported from Kinabalu although it could easily be on that mountain.

Altitude: 1500-1600m

Notes

Named after B.L. Burtt, botanist at Edinburgh, who made a series of expeditions to Sarawak and who first collected this species with Adam Martin on Gunong Murud.

Nomenclature

Type: Burtt & Martin B.5549, 16 Oct. 1967, (cultivated specimen April 1970). Sarawak, 5th Div., G. Murud (E, L, SAR).

Flags

Occurs in Countries: MY Altitude Ranges: 1,000 - 2,000m Subgenus: Vireya Habit: Epiphyte, Non-Tree

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:200

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Rhododendron buruense J.J.Sm.

Shrub to 3.5m. Twigs 3–4mm in diameter, rounded, laxly appressed-scaly, often whitish; internodes 3–16cm. Leaves 4–6 together in lax pseudowhorls with 1–2 add­itional ones on the internodes. Blade 70–160 x 4–75mm, ovate-elliptic to elliptic; apex shortly acuminate, obtuse; margin very slightly or not revolute; base broadly tapering, sometimes nearly rounded, glabrescent above when mature, laxly persistently scaly beneath. Scales small, marginal zone variously lobed, fragile and disappearing, leaving dark spots; centre small, shallowly impressed. Mid-vein grooved above, obtusely prominent beneath; lateral veins 8–12 per side, straight below, curved and anastomosing before the margin, minutely impressed above, distinctly raised beneath, reticulation lax, faintly prominent beneath. Petiole 10–20 x 1.5–2mm, slightly flattened, rugose, often white. Inflorescence 7–10-flowered. Pedicels 20–33 x c.1mm, laxly scaly and hairy. Calyx 4–5mm in diameter, obliquely disc-shaped, scaly and with some short hairs outside. Corolla 40–50mm, broadly funnel-shaped, tubular below, white; tube 20–26 x 5–6 x 7–8mm, distinctly 5-pouched at the base, straight, with some scattered scales, (almost glabrous), outside, shortly hairy inside; lobes 12–23 x 12–20mm, spreading, broadly obovate to sub-circular. Stamens unequal, exserted to c.6mm; filaments linear and sub-densely patently hairy in the proximal 1⁄3–½, filiform and glabrous distally; anthers 3–4 x 1mm, oblong, the base slightly thickened. Disc prominent, glabrous or shortly hairy on the upper margin. Ovary 6–7 x 2.5–3mm, sub-cylindrical, densely covered with sub-patent short hairs which cover small scales, abruptly contracted distally; style densely hairy and laxly scaly to the lower 2⁄3, glabrous distally; stigma rounded.

Habitat: Terrestrial on loamy limestone soil

Distribution: Indonesia, Maluku, Buru, Mt Toga and between Leksula and Mnges Waen.

Altitude: 1290-1900m

Notes

Named after the island from which it was collected.

Not recollected recently.

Nomenclature

Type: Stresemann 38. Moluccas, Buru, G. Toga, 1900m (L).

Synonymy: R. lompohense var. grandifolium J.J.Sm., Fedde Rep. 1932. 30: 169.

Flags

Occurs in Countries: ID Altitude Ranges: 1,000 - 2,000m Subgenus: Vireya Habit: Non-Tree Fl. Colour: white

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:292

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Rhododendron buxifolium Low ex Hook.f.

Shrub or tree to 5m. Twigs c.3mm in diameter, initially laxly covered with scales and sometimes with very fine papillose hairs, later glabrescent but with thick raised leaf scars; internodes 1–4cm. Leaves 5–8 in dense pseudo­whorls. Blade 10–35 x 6–25mm, broadly elliptic, ovate- or obovate-elliptic or sub-circular; apex obtuse, often rounded-obtuse, sometimes slightly emarginate, with an inconspicuous apical gland; margin slightly recurved, distinctly crenulate; base rounded, cordate, or broadly tapering, sub-densely to laxly scaly on both sides initially, early glabrescent with minute pits above; more persistently scaly beneath. Scales irregularly crenate or lobed with a narrow marginal zone; centre often large, swollen and persistent, deeply impressed. Mid-vein narrow and slightly impressed above, broad and obtusely prominent beneath; lateral veins 5–6 per side, somewhat irregular, spreading, slightly impressed above in old leaves, inconspicuous beneath, reticulation lax and faintly impressed above, obscure beneath. Petiole 1.5–3 x 1–3mm, grooved above, flattened, rugose. Flower buds (see p.327) to 17 x 11mm, ovoid, green, with the points of the bracts standing erect away from the bud. Outer bracts ovate-acuminate, the dorsal mid-vein tapering to a short subulate acumen, hairy and laxly scaly outside, hairy inside, margins ciliate near the apex only; inner ones ovate-obtuse to spathulate. Bracteoles to 20 x 1mm, linear below, sub-spathulate distally. Inflorescence of 5–10 flowers in open umbels. Flowers semi-erect to half-hanging. Pedicels 12–24 x 1–2mm, sub-stellately scaly. Calyx 3–4mm in diameter, a low scaly disc, often revo­lute. Corolla 26 x 37mm, broadly funnel-shaped or sub-­campanulate, pink to deep red, strongly honey-scented; tube 15–18 x 4–5 x 12–15mm, sub-densely scaly outside, glabrous inside, straight, the base pouched; lobes 15–18 x 13–15mm, spreading, slightly reflexed, overlapping c.½, obovate-spathulate. Stamens sub-equal, at the mouth of the tube; filaments c.13mm, linear, glabrous, pink; anthers c.3mm, oblong, pale-brown, cells obtuse or narrowed into a short distinct basal apiculus. Disc prominent, glabrous. Ovary c.4–4.5 x 2–3mm, sub-ovoid-conical, apex obtuse, abruptly contracted distally, densely scaly and occasionally with some very sparse hairs; style 9 x 1mm, glabrous, or scaly at the base for c.1mm, red, as long as the stamens; stigma c.2mm in diameter, red, rounded. Fruit 14–18 x 7–8mm, ovoid-fusiform, brown-scaly. Seeds 1.7mm, without tails c.1mm, the longest tail 0.4mm.

Habitat: In forest above 3100m, but more frequent in shrubberies and in open places amongst the granite rocks, up to 3900m.

Distribution: Malaysia (Borneo), Sabah, Mt Kinabalu.

Altitude: 3100-3900m

Notes

Latin – Buxus – Buxus sempervirens – ‘the European box’; folium – leaf. An allusion to the similarity of the leaves to that of this shrub.

The variety robustum recognised by Sleumer (1960) has little significance, except to indicate the effects of exposure: the type specimen is from the upper end of the range from an exposed site and thus has small leaves compared with the plants lower down. It is one of the most magnificent botanical sights on Mt Kinabalu when in full flower on a fine sunny day.

Nomenclature

Type: Low s.n., March 1851. North Borneo, Mt Kinabalu, 2745–4096m, top (K, CGE, L).

Synonymy: R. buxifolium var. robustum Sleumer, Reinwardtia 1960. 5: 173.

Flags

Occurs in Countries: MY Altitude Ranges: 3,000 - 4,000m Subgenus: Vireya Habit: Tree Fl. Colour: pink, red

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:202

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Rhododendron buxoides Sleumer

Shrub to 2m. Twigs 2–3mm in diameter, scaly at first with stalked scales, warty with persistent scale bases after the scales have gone; internodes 0.5–1.5cm. Leaves in tight to loose pseudowhorls, 2–5 together or spirally arranged. Blade 10–30 x 4–14mm, broadly obovate to elliptic; apex obtuse, to rounded, often emarginate; margin strongly and broadly revolute, sometimes crenulate with impressed scales; base tapering, decurrent; densely and persistently scaly on both sides. Scales large, thick, rounded, entire, strongly impressed; the narrow margin tending to disintegrate, the centre persistent. Mid-vein impressed above, raised below; lateral veins 3–4 per side, obscure to strongly raised below at least when dry, reticulation obscure. Petiole 1.5–2mm. Bracts c.5mm, obovate, densely scaly and white-hairy distally outside and with a ciliate margin. Inflorescence 2–4 flowers in an open umbel, hanging vertically. Pedicels 6–14 x 0.5–0.6mm, slender, densely scaly, without hairs. Calyx obliquely disc-shaped, obscurely lobed or undulate, densely scaly. Corolla tubular, red; tube 13–15 x 3–4 x 4–7mm, completely very densely covered in thick rounded scales, glabrous inside; lobes 3–4 x 3–4mm, erect, obovate, spathulate, or sub-circular, scaly in the central part outside. Stamens exserted to c.3mm; filaments linear, glabrous; anthers 1.5 x 1mm, obovoid. Disc glabrous. Ovary c.2.5 x 1.5mm, conical, densely scaly, gradually tapering distally; style scaly at the base only, glabrous distally, about as long as the corolla; stigma slightly broadened, obliquely truncate. Fruit 7–9 x 3–4mm, shortly cylindrical, deeply grooved. Seed 1.2–1.5mm, without tails c.1mm, the longest tail to 0.4mm, mostly broadly triangular at one end with a short narrow tail at the other.

Distribution: Malaysia (Borneo), Sarawak, Mt Murud, Mt Mulu and Batu Lawi

Altitude: 1800-2300m

Notes

Like the ‘European box’ Buxus sempervirens, the leaves being superficially similar.

Flowers Apr, Oct.; probably continuously.

Sleumer (1973) commented that this species was ‘close to’ R. perakense but differed in the slightly crenulate leaves, red corolla and the bracts being both hairy and scaly outside. It is usually a much larger plant with bigger leaves and flowers. This species is not known to have been cultivated. In its small, dull red, densely scaly flowers it very much parallels R. inconspicuum and R. yelliotii from New Guinea. The almost tail-less seeds are like those of other species from the highest points on high mountains.

Nomenclature

Type: Nooteboom & Chai 1973, 6 April 1970. Borneo, Sarawak, 5th Div., Mt Murud, towards the top (L, K, SAR).

Flags

Occurs in Countries: MY Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Vireya Habit: Non-Tree Fl. Colour: red

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:46

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Rhododendron caesium Hutchinson

Shrub, 1-2 mm. Young growth sparsely lepidote. Leaves subdeciduous, flat or rarely slightly revolute, ± oblong-elliptic or rarely oblong-ovate, 30-42 x 13-18 mm, apex subacute or rounded, base rounded or somewhat cuneate, the lower surface with an indumentum of distant, straight or slightly curved loriform setae, which also occur on the margins and petioles, the surface white-papillose and with distant, equal, golden scales, upper surface glabrous and elepidote. Inflorescence (l-)2-3-flowered, pedicels 12-15 mm, sparsely lepidote. Calyx obscurely lobed, lobes 1-2 mm, sparsely lepidote and loriform-ciliate. Corolla yellow, c. 18 mm, tube 9-10 mm, lepidote and glabrous outside. Ovary lepidote, glabrous. Capsule cylindric, c. 10 mm

Habitat: Rocky slopes

Distribution: China (SW & C Yunnan)

Altitude: 2450-3050m

Nomenclature

Type: a cultivated plant said to be from seed of Forrest 26798 (holo. K, iso. E)

Flags

Occurs in Countries: CN Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Rhododendron Habit: Non-Tree

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):152

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Rhododendron caespitosum Sleumer

Prostrate, cushion-forming, low shrub, forming vertical patches up to 2cm in depth and 20cm in diameter, extending by prostrate, elongate, not, or sparsely, branched stoloniform shoots which root freely into the substrate. These eventually become erect and branch freely. Twigs c.1mm in diameter, covered in shortly stalked sub-stellate, brown scales at first, these falling and leaving a minutely warty surface with scale stalks up to 0.2mm high. Leaves spirally arranged along the elongate shoots, densely crowded towards the erect branch tips. Blade 3–6 x 2–3mm, elliptic; apex shortly acuminate, broadly acute to obtuse or rounded; margin entire or sub-crenulate with a broad and only faintly demarcated sub-cartilaginous edge; base tapering, laxly to sub-densely scaly at first on both sides but these scales disappearing quickly from the upper surface. Scales orange-brown, with a broad and deeply incised marginal zone. Mid-vein only visible when fresh, all veins obscure after drying. Petiole 1–2 x c.0.5mm, weakly grooved above when fresh. Flower buds brown, 5–6 x c.3mm. Bracts long acuminate, the tips standing away from the bud, glabrous outside but with scales along the margins. Bracteoles c.4mm, filiform. Flowers solitary, horizontal to half-hanging. Pedicels 2–3 x c.1mm, densely scaly. Calyx a low disc, densely white-scaly. Corolla 12 x 7mm, pale pink; tube 7 x 5 x 4mm, cylindrical but contracted just below the lobes, densely scaly outside, glabrous inside; lobes 3 x 3.5mm, without scales, semi-erect to horizontally spreading, overlapping to c.2⁄3. Stamens 6mm, curving distally so that the anthers fill the upper part of the tube; filaments white, glabrous; anthers 1–1.1mm, brownish-purple. Disc glabrous. Ovary 5 x 3mm, densely white-scaly, abruptly contracted distally; style 2–2.5mm, glabrous, reddish-brown; stigma c.1mm in diameter, dark pink. Fruit 11 x 5mm, erect, broadly fusiform and densely brown-scaly, the pedicels elongating to 5–6mm, on ripening the outer layer irregularly peeling back and then the valves splitting to c.45°. Seeds 1.8–2.2mm, without tails to 0.8mm, the longest tail to 0.7mm.

Habitat: Growing in the high open valleys dominated by tree-ferns and forming cushions on their trunks. Probably protected from frost and with optimal shading by growing usually about mid-way up the tree-fern trunks (Argent et al. 1999).

Distribution: Indonesia, New Guinea (W), Mt Trichora (Mt Wilhelmina), Lake Habbema vicinity.

Altitude: 2400-3500m

Notes

Latin – caespitosus, growing in tufts like grass, generally of low growing plants.

Nomenclature

Type: Brass 9039, Aug. 1938. New Guinea, Mt Wilhelmina, Habbema Lake (A, L).

Flags

Occurs in Countries: ID Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Vireya Habit: Non-Tree Fl. Colour: pink

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:141

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Rhododendron calendulaceum (Michx.) Torrey

Shrub or small tree to 10m tall, usually non-rhizomatous; young twigs reddish brown, sparsely to densely covered with unicellular hairs and multicellular eglandular hairs. Vegetative bud scales glabrous abaxially; margin unicellular-ciliate. Leaf blade membranaceous, ovate or obovate to elliptic, (4.5-)5.6-7.7(-9.1) x (1.3-)1.8-2.6(-3.3)cm; base acute to oblique; apex acute to obtuse, often mucronate; adaxial surface sparsely covered with multicellular eglandular and unicellular hairs or with only multicellular eglandular hairs, or glabrous; the midvein densely covered with unicellular hairs; abaxial surface sparsely to densely covered with multicellular eglandular hairs or glabrous; the midvein densely covered with unicellular and multicellular eglandular hairs,rarely densely covered with unicellular hairs and multicellular eglandular hairs, or with only unicellular hairs; margin entire, ciliate with multicellular eglandular hairs; petiole 0.3-0.6(-0.7)cm long, sparsely to densely covered with unicellular hairs and multicellular eglandular hairs. Flower bud scales chestnut brown; abaxial surface glabrous, rarely very sparsely covered with unicellular hairs; margin glandular. Flowers appearing before or as the leaves expand; inflorescence a shortened raceme of 5 to 9 flowers. Pedicels (0.7-)0.8-L2(-1.4)cm long, sparsely to densely covered with unicellular hairs and densely covered with multicellular gland-tipped hairs, or with multicellular eglandular hairs, or both. Sepals (0.1-)0.2-0.3cm long, often varying in length on the same flower; margins glandular-fimbriate, frequently setose; abaxial surface sparsely to densely covered with unicellular hairs and multicellular gland-tipped hairs, rarely with unicellular hairs and multicellular eglandular hairs or with only unicellular hairs. Corolla orange to flame-coloured, fragrance acrid, the tube longer than the limb and abruptly expanding into it; upper corollalobe (1.4-)1.6-2.2(-2.3) x (1.2-)1.5-2.2(-2.5)cm; lateral lobes 1.8-2.6(-3.0) x (0.9-)1.0-1.4(-l .5)cm; corolla tube (1.6-) 1.8-2.2(-2.4)cm long, (0.2-)0.3-0.4(-0.5)cm wide at base; outer surface of corolla sparsely to densely covered with unicellular hairs and densely covered with multicellular gland-tipped hairs which often continue up the corolla lobes; inner surface of corolla sparsely to densely covered with unicellular hairs. Stamens (5.2-)5.7-6.7(-7.2)cm long, with dense terete or flattened unicellular hairs on proximal (1.9-)2.3-3. l(-3.2)cm of filament, exserted (3.4-)3.7-4.8(-5.4)cm beyond throat of corolla. Style (5.5-)5.9~6.8(-7.2)cm long, exserted (3.8-)4.2-5.3(-6.0)cm beyond throat of corolla, with dense unicellular hairs on proximal (0.0-) 0.3-1.3(-1.7)cm; stigma 0.1-0.2(-0.3)cm wide. Ovary 0.3-0.4(-0.5)cm long, (0.1-)0.2-0.3cm wide at the base, densely covered with multicellular eglandular hairs and dense unicellular hairs, rarely with multicellular gland-tipped hairs and unicellular hairs, or with all three types of hairs. Capsules (1.5-)1.8-2.6(-2.9) x (0.5-)0.6-0.8(-0.9)cm, ovate, sparsely covered with unicellular hairs and sparsely to moderately covered with either multicellular eglandular hairs or less often eglandular hairs. Seeds pale to dark chestnut brown, ovate or elliptic to fusiform, (1.7-)2.4-3.9 (-4.2) x (0.6-)0.9-1.5(-1.9)mm, body (0.8-)l.l-1.7(-2.1) x (0.2-)0.4-0.7(-0.8)mm, the testa expanded and dorsiventrally flattened, surrounding the body, the cells elongate, with transverse end-walls.

Habitat: Found in open, dry sites on southern and western exposures of hills and mountain-sides.

Distribution: USA: Northern West Virginia, south through the mountains of Virginia, North Carolina, Tennessee and Georgia. Generally restricted to the Ridge and Valley Province and Southern Appalachians, with occasional populations in the Cumberland Mountains and in the eastern edge of the Cumberland Plateau in Ohio and Kentucky. Not known west of die Tennessee River Valley in Tennessee. Extending into the Upper Piedmont in North and South Carolina and as far soutii as Meriwether Co., Georgia. Collections from Tarrytown, New York that are R. calendulaceum have been suggested as native in the past (Barnhart, 1895). However, all of the collections are nearly a century old and this is well north of the range of the species. Most likely these were cultivated plants that had persisted.

Altitude: 180-1000m

Illustrations:

Notes

The morphological characters which are the most useful in distinguishing R. cumberlandense from R. calendulaceum are outlined in Table 6. These characters are most useful in the field. Identification can be made with much more confidence when a population is Investigated, as opposed to an isolated specimen. Individuals may be further identified by taking into consideration the geographic location and the altitude in combination with the height and habit of the plant. Rhododendron cumberlandense is primarily a plant of the higher elevations of the Cumberland Plateau and Mountains where it flowers well after the leaves have expanded (this is one of the most useful characters). It is usually of smaller stature and glaucous leaves are much more common in populations of R. cumberlandense than in R. calendulaceum. The results of this study show that R. calendulaceum is morphologically separable from R. cumberlandense when a combination of characters is used in conjunction with geographic location. These two species can be most easily identified in the field where populations can be examined for variability in pedicel indumentum and sepal margin condition, and where phenological conditions can be clearly discerned. It is still difficult to identify some individual specimens because the range of morphological variation in R. calendulaceum may occasionally obscure the differences between the two species. However, difficulty in identification is not necessarily a valid reason to consider R. cumberlandense as conspecific with R. calendulaceum (Willingham, 1973). Rhododendron calendulaceum was once thought to be the red-orange-flowered taxon in the hybrid swarm on Gregory Bald, Blount Co., Tennessee. However, Li (1957) showed that all individuals sampled from that locality were diploid, and thus the red-orange species is the diploid, R. cumberlandense. However, a few specimens from Gregory Bald are indistinguishable morphologically from R. calendulaceum, and this species Ukely occurs on the bald in small populations. Although of low probability, hybrids with the tetraploid are not impossible since unreduced gametes are fairly frequent in the Ericaceae (Li, 1957; Goldy & Lyrene, 1984). The putative hybrids listed in the Appendix exhibit a combination of characters that occur where R. cumberlandense is not known to occur, and with species whose blooming times overlap with that of R. calendulaceum, but not R. cumberlandense. As such, these plants are most likely the result of hybridization by unreduced gametes.

Several specimens previously classified as 'intermediates'fit best Into the natural range of variation of R. calendulaceum and are best classified as the tetraploid, based upon morphological Information. Rhododendron cumberlandense is less morphologically variable than R. calendulaceum, in that the pedicels and sepal margins are almost always eglandular, and only occasionally one or the other will be somewhat glandular. From the R. cumberlandense populations examined, the only individuals with both completely glandular pedicels and sepal margins occurred In Alabama, in a population of hybrids between R. arborescens and R. cumberlandense. By contrast, this character combination occurs frequently in R. calendulaceum. Field-work In Virginia and North Carolina confirms the generally eglandular nature of R. cumberlandense and the glandular nature of R. calendulaceum.

Principal component analysis of 39 OTUs and up to 40 floral, bud-scale and vegetative characters were performed. Most of the characters were so variable that they only resulted in adding a great amount of 'noise'to an akeady complex problem. Therefore a series of analyses was performed, and from these, six characters (see Table 5) were chosen for an additional analysis. These six characters consistently recurred In each of the previous analyses as characters which were heavily weighted In the first and second principal components. The results of this analysis, using 39 OTUs and six characters, are shown In Fig. 25. Some definite trends are evident. Using the character of flowering time (which was not used In the principal component analysis) tentative assignment of specimens to either R. cumberlandense or R. c(ilendulaceum was made. There Is a trend towards Increasing floral size from the diploids to the tetraploids. However, there is no morphological gap in corolla size. The variation In the Indumentum of the pedicels and In the sepal margins from eglandular to glandular Is an Important trend. In the R. cumberlandense specimens, the pedicels and sepal margins are usually both eglandular, while in most specimens of R. calendulaceum the pedicels and sepals are glandular. Leaf pubescence appears to be highly variable. There is only a weakly defined trend towards densely unicellular pubescent leaves in R. calendulaceum.

The tetraploid flame azalea, R. calendulaceum, has long been noted for its morphological variation (Bartram, 1791; Rehder, 1921; Skinner, 1955, 1961; Galle, 1968, 1985). This species is found throughout the Blue Ridge and into the Ridge and Valley and Piedmont provinces. The closely related R. cumberlandense is diploid and has a more discontinuous occurrence within Its geographic range than the tetraplold, occurring primarily In the Cumberland Plateau and Mountains. While these two taxa are distinct biological entities, they are often very difficult to separate on the basis of morphology. This Is due to the great range of morphological variation In R. calendulaceum (WEEngham, 1973; personal observation) and also in part to the natural variation found in populations of R. cumberlandense. The characters which have been used to distinguish between these two species (besides chromosome number) include flavonoid chemistry (King, 1977a, 1980), flowering time and leaf expansion (Lemmon, 1938; Braun, 1941; Skinner, 1955, 1961; Galle, 1968, 1985), size of the corolla (Braun, 1941; Skinner, 1955, 1961; Galle, 1968, 1985), pubescence of the abaxial surface of the leaves (Skinner, 1955, 1961; Galle, 1968, 1985), and habit (Braun, 1941; Skinner, 1955, 1961; Galle, 1968, 1985). Rhododendron calendulaceum is characterized in the Eterature as tall usually non-stoloniferous shrubs possessing flowers which open before or as the leaves expand, and are up to 4cm across. In addition, R. calendulaceum is cited as possessing unicellular pubescent abaxial leaf surfaces (Rehder, 1921; Braun, 1941; Skinner, 1955,1961; Galle 1968,1985). By contrast, R. cumberlandense has been described as a low-growing stoloniferous shrub, with smaller, redder flowers, and more glabrous leaves than R. calendulaceum(Bmw, 1941; Skinner, 1961). The primary difference which has been emphasized in the literature has been the flowering of R. cumberlandense after the leaves have fully expanded. Difficulties in identification arise because there are no gaps in the flower size and colour or in leaf size or pubescence, and the phenologlcal differences are sometimes difficult to discern from herbarium material. Both R. cumberlandense and the 'early' and late'-blooming forms of R. calendulaceum have been studied in the Nantahala Mountains and nearby areas In North Carolina and Georgia by Willingham (1973,1974, 1975,1976). No morphological or phenological gaps were found between the early and late forms of R. calendulaceum. To distinguish between the two species WElingham used the following characters: growth habit, leaf expansion, flower colour, flower size, presence or absence of a blotch, pollen size (tetrad), pollen viability, cuticular ridging of the epidermis, stomata size and flavonoid compounds. Of these characters, only flavonoid compounds, pollen size and pollen viability were considered reliable characters in distinguishing between the two species by Willingham. He did note the difficulty in distinguishing the later-blooming individuals of R. calendulaceumfmm Individuals of R. cumberlandense, as late-blooming R. calendulaceum often has most of its leaves unfolded (however, there are usually some vegetative bud scales remaining on the plant). These late-blooming individuals almost always possess multicellular gland-tipped hairs on the pedicels and the sepal margins, whereas R. cumberlandense has eglandular pedicels and sepal margins. Earlier-blooming individuals of R. calendulaceum appear to be more variable in pedicel and sepal margin condition, with either the pedicel or sepal margins being eglandular. Plants of R. calendulaceum with both eglandular pedicels and sepal margins are usually clearly blooming before or with the expansion of the leaves. In Kentucky the pedicels and sepal margins of R. calendulaceum are more often eglandular than in West Virginia where they are usually glandular.

Chromosome number: 2n = 52 (Sax, 1930; Janaki-Ammal et al., 1950; Li, 1957)

Flowering from May to July

Flags

Occurs in Countries: US Altitude Ranges: 0 - 1,000m: 1,000 - 2,000m Subgenus: Pentanthera Habit: Tree

Kron, K.A. (1993) A Revision of Rhododendron Section Pentanthera. Edinburgh Journal of Botany 50(3):296

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Rhododendron caliginis Kores

Small, straggling, much-branched shrub to 50cm. Twigs 1–2mm in diameter, slender, rounded, tips densely scaly with brown, stellate scales, the older parts glabrescent, smooth; internodes 1–8cm. Leaves 4–7 together in tight pseudowhorls, often noticeably different in size in the same pseudowhorl. Blade 10–70 x 1–6mm, linear or occasionally very narrowly ovate or narrowly elliptic; apex sub-obtuse; margin entire or slightly revolute; base very broadly tapering or rounded, very densely red-brown scaly on both sides initially. Scales deeply stellately divided, sub-sessile or shortly dendroid, each on top of a minute epidermal tubercle, becoming glabrous and smooth above, persistently red-brown scaly beneath. Mid-vein faintly impressed above, as thick as the petiole and prominently raised beneath; lateral veins obscure. Petioles 2–5 x 1–1.5mm, weakly grooved distally, densely brown-scaly. Flower buds to 12 x 7mm, densely brown-scaly when young, becoming green just before opening, narrowly elliptic, sharply acute at the apex. Outer bracts subulate, inner ones ovate-subulate to ovate-acuminate, densely stellate-scaly in a patch on the outer upper part, glabrous otherwise, margin fringed with scales. Bracteoles to 8mm, linear to very narrowly obovate, margin laxly fringed with scales. Inflorescence of solitary flowers or up to 3 together. Flowers hanging vertically downwards. Pedicels 6–12mm, slender, densely stellately scaly. Calyx c.2.5mm in diameter, small, disc-like, densely stellate-scaly externally. Corolla 30–35mm, white to cream, sometimes very pale pink, without scent, tubular below, slightly expanded at the mouth, a little curved, zygomorphic; tube 20–25 x 4–6 x 6–10mm, densely stellately scaly and without hairs outside, glabrous inside; lobes 7–9 x 6–9mm, broadly obovate to sub-circular, spreading horizontally and overlapping to c.¼, scaly at the base outside. Stamens clustered on the upper side of the flower, unequal, exserted to c.10mm; filaments white, linear, glabrous or sparsely hairy in the proximal ½; anthers c.2 x 1mm, brown. Disc glabrous below, densely stellate-scaly on the upper margin. Ovary sub-ovoid, gradually tapering to the style, very densely stellate-scaly and conspicuously 5-ribbed, c.7 x 3.5mm; style greenish-white, on the upper side of the tube, slender, scaly throughout the proximal 1⁄3, glabrous distally or with sparse white hairs almost to the top, equalling the corolla in length when receptive; stigma white or green, club-shaped to globose, obscurely 5-lobed. Fruit fusiform, the valves ultimately curling right back, the placentae breaking away at the base and irregularly splaying apart.

Habitat: Open sub-montane shrubberies, cliffs and on fallen logs.

Distribution: Indonesia, New Guinea (W), Koruppun Valley (139°38'E 4°28'S). Papua New Guinea, West Sepik Province, Hindenburg Range, Mt Amdutakin; Victor Emanuel Range, Mt Womtakin. Enga Province, Laiagam–Porgera Divide, Mt Maip. Western Highlands District, Mt Sigal Mugal; Waghi–Sepik Divide, Mt Manduil.

Altitude: 2400-2900m

Notes

Latin – caligo – of mist or fog, the type collection being made from plants that seemed perpetually enshrouded in mist.

A striking species owing to its linear leaves which are densely covered with dark brown, dendroid scales when immature and its apparent association with limestone outcrops. Similar to R. hooglandii from which it is best distinguished by its subulate bracts which are densely scaly outside. For a discussion of other differences see under R. hooglandii.

Nomenclature

Type: Kores WEI 1600, 7 Aug. 1976. Papua New Guinea, West Sepik Province, Victor Emanuel Range, Mt Womtakin, 2850m (LAE, BISH, E, L).

Flags

Occurs in Countries: ID, PG Altitude Ranges: 2,000 - 3,000m Subgenus: Vireya Habit: Non-Tree Fl. Colour: cream, green, pink, white

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:78

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Rhododendron callimorphum Balfour f. & W. W. Smith

Shrub, 0.6-2(-3)m; young shoots shortly stipitate-glandular. Leaves broadly ovate to orbicular, 3.5-7 x 3-5cm, 1-1.5 X as long as broad; apex rounded, acuminate, base cordate, upper surface glabrous, lower surface glaucous, with minute red punctate glands, sometimes also stipitate-glandular at base, especially on midrib; petioles 1.2-2cm, stipitate-glandular, at least when young. Inflorescence 4-8-flowered; rhachis c.3mm; pedicels c.l5mm, stipitate-glandular. Calyx c.2mm, stipitate-glandular. Corolla campanulate, white to rose-pink, sometimes with purple flecks and a faint basal blotch, 30-40mm. Ovary stipitate-glandular; style glabrous or with a few glands at base. Capsule 15-20 x 3-4mm, curved.

Habitat: Stony slopes, thickets, etc.

Distribution: China(W Yunnan)

Altitude: 3000-4000m

Flags

Occurs in Countries: CN Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: purple, rose, white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):262

Rhododendron callimorphum var. callimorphum

Flowers pink

Illustrations:

  • Bot. Mag. 145: t.8789 (1919)
Nomenclature

Type: China, W Yunnan, Shweli/Salween divide, 25°20'N, 10000ft, Forrest 12019 (holo. E; iso. K)

Synonymy: R. cyclium Balfour f. & Forrest, Notes R.B.G. Edinb. 13:39 (1920). Type: China, W Yunnan, N'Maikha/Salween divide, vi 1919, Forrest 18044 (holo. E; iso. K). R. hedythamnum Balfour f. & Forrest, ibid. 13:261 (1922). Type: China, Mid W Yunnan, Tali Range, W flank, 11000ft, vi 1913, Forrest 11601 (holo. E; iso. K). R. hedythamnum Balfour f. & Forrest var. eglandulosum Handel- Mazzetti, Anz. Akad. Wiss. Wien 79: 3 (1923). Type: China, Yunnan, in lateris orient, montis Dzang-shan prope urbem Dali, 3900-4250m, Handel-Mazzetti 8712, n.v.

Rhododendron callimorphum var. myiagrum (Balfour f. & Forrest) Chamberlain

Notes

Cowan & Davidian maintain R. myiagrum at specific rank while admitting that the only significant difference between it and R. callimorphum is the flower colour, a distinction that certainly does not merit more than varietal rank.

Nomenclature

Synonymy: R. myiagrum Balfour f. & Forrest, Notes R.B.G. Edinb. 13: 52 (1920). Type: China, W Yunnan, N'Maikha/Salween divide, 10000ft, vi 1919, Forrest 17793 (holo. E; iso. K).

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Rhododendron calophytum Franchet

Tree, (2-)5-12m. Leaves oblong-oblanceolate, 14-30 x 4-7.2cm, 3.5-6 x as long as broad, apex cuspidate to acuminate, base cuneate, lower surface glabrous when mature, or with vestiges of juvenile indumentum persisting along the midrib; petioles 1 -2 cm, stout, glabrous or with a thin indumentum. Inflorescence 5-30-flowered; rhachis 12-20 mm; pedicels 30-55 mm, glabrous. Calyx c. 1 mm, glabrous. Corolla 5-7-lobed, open-campanulate, glabrous, pinkish white with purple flecks and a basal blotch, 40-60 mm. Stamens 15-20, filaments puberulent below. Ovary and style glabrous; stigma discoid. Capsule 25-33 x 6-12 mm.

Habitat: Forests, etc.

Distribution: China (C & E Sichuan, NE Yunnan)

Altitude: 1800-4000m

Flags

Occurs in Countries: CN Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Tree Fl. Colour: pink, purple, white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):228

Rhododendron calophytum var. calophytum

Leaves 18-30 cm long, apex acuminate; inflorescence 15—30-flowered

Illustrations:

  • Bot. Mag. 153: t. 9173 (1929)
  • Fang, PI. Omeiens. t. 26 (1942)
Nomenclature

Type: China, Sichuan,Moupine, 4000 m, 1870, Pere David (iso. E)

Rhododendron calophytum var. openshawianum (Rehder & Wilson) Chamberlain

Illustrations:

  • Fang, PL Omeiens. t. 27 (1942)
Nomenclature

Type: China, W Sichuan, Yung Ching hsien, Wa Wu shan, 2300-2800 m, 18 ix 1908, Wilson 3414 (holo. A; iso. K)

Synonymy: R. openshawlanum Rehder & Wilson in PI. Wilsonianae 1: 543 (1915)

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Rhododendron calosanthes Sleumer

Shrub, c.40cm. Twigs slender, at first laxly sub-stellate, the older parts glabrescent, smooth, 1–2mm in diameter; internodes 1.5–2.5cm. Leaves 4–6 in loose pseudowhorls. Blade 20–25 x 5–9mm, narrowly elliptic; apex sub-acutely tapering or sub-acuminate; margin sub-crenulate with impressed scales at first in the crenulations or sub-entire; base tapering, initially laxly scaly on both sides, slowly glabrescent above, sub-persistently scaly beneath. Scales with the thin marginal zone sub-stellate; centre small, impressed. Mid-vein hardly impressed above or flat, thick and obtusely prominent beneath; lateral veins inconspicu­ous. Petiole 2–3 x 0.7–1mm. Bracts to 20 x 10mm, membranous, red, glabrous and shining outside, ovate; outer ones acuminate-apiculate, inner ones obtuse. Inflorescence of solitary or paired, hanging, flowers. Pedicels 15–20mm, slender, densely stellately scaly. Calyx c.2.5mm in diameter, obliquely disc-shaped, often covered by the basal lobed part of the corolla tube, hardly lobed, scaly outside. Corolla 30–35mm, weakly zygomorphic, red, thin; tube 20–25 x 5–6 x 8–10mm, straight, laxly sub-stellately scaly outside, otherwise glabrous; lobes c.10 x 5–8mm, half-spreading, broadly obovate-oblong. Stamens very unequal, the longest reaching the mouth, hardly exserted; filaments linear, glabrous; anthers 1.5–1.8 x 1mm, obovate-oblong, base obtuse. Disc prominent, glabrous. Ovary 4 x 1.5mm, sub-obliquely cylindrical, densely covered with sub-stellate, brown scales but without hairs, tapering distally; style slender with some scales at the base, glabrous distally; stigma rounded, shortly 5-lobed.

Habitat: In alpine or semi-alpine shrubby vegetation. Rare.

Distribution: Indonesia, New Guinea (W), Star Mts, Mt Antares.

Altitude: 3000-3200m

Notes

Greek – kalos – beautiful; anthos – flowers. The rhododendron with beautiful flowers.

Sleumer (1961) commented that it was related to R. rubrobracteatum but differed in having smaller leaves and a larger corolla.

Nomenclature

Type: Kalkman 454227, July 1959. New Guinea (C), Star Mts, Mt Antares, 3000–3200m (L).

Flags

Occurs in Countries: ID Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Vireya Habit: Non-Tree Fl. Colour: red

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:233

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Rhododendron calostrotum Balfour f. & Kingdon Ward

Prostrate, matted or erect intricate shrub, 0.05-1-5 m. Young growth densely lepidote, not loriform-setose, or if so the setae quickly deciduous. Leaves suborbicular to oblong-ovate, rarely oblong-obovate, 11-33 x (2-)4-20 mm, upper surface matt with persistent, dried-out scales, rarely elepidote and somewhat shining, margins sparsely loriform-ciliate, lower surface with dense, overlapping scales arranged in 3-4 tiers, those of the outermost tier with long stalks and cup-shaped discs. Inflorescence 1 -5-flowered, pedicels lepidote with usually many long-stalked scales with cup-shaped discs. Calyx with frequently unequal, oblong to ovate lobes, rounded at the apex, variably lepidote and filiform-acicular pubescent on the surface, margins loriform-setose, inner surface puberulent. Corolla magenta, more rarely pink or purple, often with darker spots on the upper lobes, 18-28 mm, tube 7-12(-14) mm, pilose outside, occasionally somewhat lepidote also. Stamens 10. Ovary lepidote, glabrous. Capsule 6-9 mm, lepidote.

Flags

Occurs in Countries: CN, IN, MM Altitude Ranges: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: pink, purple

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):115

Rhododendron calostrotum subsp. calostrotum

Leaves ± obtuse, lepidote above, (7-)9-20 mm broad; decumbent or erect shrubs. Scales on the undersurface clearly borne in 3-4 tiers; leaves 12-22 mm long. Flowers 1-2 in each inflorescence; pedicels 16-27 mm

Habitat: Stony alpine meadows and cliffs

Distribution: N Burma, China (W Yunnan)

Altitude: 3300-4250m

Illustrations:

  • Bot. Mag. 149: t. 9001 (1923)
  • The Garden, 88:268 (1924)
  • Gard. Chron. 87:511 (1930)
  • Urquhart, The Rhododendron 1: t. 9 (1958)
Nomenclature

Type: NE Burma, ridge of the Naung chaung/Nwai Divide, 16 vii 1914, Kingdon Ward 1790 (holo. E)

Rhododendron calostrotum subsp. keleticum (Balfour & Forrest) Cullen

Leaves ± acute, elepidote above, 2-7(-9) mm broad; prostrate shrublet

Habitat: Stony alpine slopes

Distribution: NE Burma, China (NW Yunnan, SE Xizang)

Altitude: 4250-4550m

Illustrations:

  • Gard. Chron. 83:333 (1928)
Notes

Subsp. keleticum is found only in the area of overlap between R. calostrotum and R. saluenense subsp. chameunum, at the highest altitudes; it grades into subsp. riparium below c. 4200 m.

Nomenclature

Synonymy: R. keleticum Balfour f. & Forrest, Notes R.B.G. Edinb. 13:50 (1920). Type: China, SE Tibet, Tsarong, Salween/Kiu chiang Divide, viii 1919, Forrest 18918 (holo. E). R. radicans Balfour f. & Forrest, op. cit.: 290 (1922). Type: China, SE Tibet, Tsarong, Salween/Kiu chiang Divide, Forrest 19919 (holo. E)

Rhododendron calostrotum subsp. riparioides Cullen

Leaves ± obtuse, lepidote above, (7-)9-20 mm broad; decumbent or erect shrubs. Scales on leaf undersurface ± flat, the tiers indistinct; leaves 22-33 mm long.

Habitat: Alpine meadows, cliffs, slopes

Distribution: China (NW Yunnan)

Altitude: 3650-4450m

Notes

Very similar to subsp. riparium but differing in its larger leaves and flowers, and the scales on the leaf undersurface not being so clearly tiered, presenting a smooth, almost felted appearance. Restricted to the mountains around Weixi (Wei hsi), where R. saluenense subsp. chameunum also occurs. It may be a stabilised hybrid between R. calostrotum and subsp. chameunum.

Nomenclature

Type: China, Yunnan, on the Shui-lu-shan W of Wei hsi, 13000 ft, Forrest 25503 (holo. E)

Rhododendron calostrotum subsp. riparium (Kingdon Ward) Cullen

Leaves ± obtuse, lepidote above, (7-)9-20 mm broad; decumbent or erect shrubs. Scales on the undersurface clearly borne in 3-4 tiers; leaves 12-22 mm long. Flowers 2-5 in each inflorescence; pedicels 10(-15) mm

Habitat: Open rocky slopes and hillsides, often beside streams or in swamps, 3050-4550 m

Distribution: India (Arunachal Pradesh), ne Burma, China (NW Yunnan, S & SE Xizang)

Notes

A northerly vicariant of subsp. calostrotum, occupying quite a wide distribution area. The small-leaved variants, described as R. nitens and R. calciphilum are in many ways intermediate to subsp. keleticum.

Nomenclature

Synonymy: R. rivulare Kingdon Ward, Gard. Chron. 86:503 (1929) non Handel-Mazzetti (1921). Type: as for R. riparium. R. riparium Kingdon Ward, Notes R.B.G. Edinb. 16:180 (1931). Type: China, S Tibet, Doshong La, 10-11000 ft, Kingdon Ward 5828 (holo. BM, iso. E). R. calciphilum Hutchinson & Kingdon Ward, Notes R.B.G. Edinb. 16:179(1931). Type: Upper Burma, Seinghku Wang, 11-14000 ft, on limestone, Kingdon Ward 6984 (iso. E). R. nitens Hutchinson, Gard. Chron. 99:135 (1936). Type: a cultivated plant (holo. K). R. kingdonii Merrill, Sunyatsenia 3:256 (1937). Type: as for R. riparium. R. calostrotum var. calciphilum (Hutchinson & Kingdon Ward) Davidian, R.H.S. Rhodo. Yearbook 8:87 (1954)

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Rhododendron calvescens Balfour f. & Forrest

Shrub, 1 -2.5m; young shoots shortly stipitate-glandular, also with a detersile dendroid indumentum. Leaves elliptic to ovate, 6—10 x (2.5-)3.2—4cm, 1.5-2.5(-3) x as long as broad, apex rounded, apiculate, base rounded, upper surface glabrous except for a thin veil of indumentum over the midrib, lower surface with a few stipitate glands and a thin detersile indumentum that is sometimes restricted to near the midrib at the base; petioles l-2cm, glandular and with a sparse indumentum. Inflorescence lax, c.5-flowered; rhachis c.5mm; pedicels 15-28(-35)mm, shortly stipitate-glandular. Calyx 2-3mm, glandular. Corolla funnel-campanulate, white flushed rose, with a few crimson markings, c.35mm. Ovary densely glandular, also with a varying proportion of rufous dendroid hairs; style glabrous. Capsule c.15 x 4mm, curved.

Habitat: Conifer forests, scrub, open rocky places

Distribution: China (SE Xizang, NW Yunnan)

Altitude: 3350-4550m

Notes

Var. duseimatum may be a chance hybrid between R. selense and var. calvescens, especially since it has only been collected once and then from a well-known locality. R. calvescens is closely allied to R. dasycladoides, sharing with it the rufous dendroid-hairy ovary, but differing in the lack of bristles and in the more persistent leaf indumentum.

Flags

Occurs in Countries: CN Altitude Ranges: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: crimson, rose, white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):275

Rhododendron calvescens var. calvescens

Leaves 3.2-4cm wide, 1.5-2.5 X as long as broad; pedicels 15-20mm

Nomenclature

Type: China, SE Xizang, Tsarong, on Dokar La, 11000ft, vii vii 1917, Forrest 14331 (holo. E; iso. K)

Rhododendron calvescens var. duseimatum (Balfour f. & Forrest) Chamberlain

Leaves 2.5-3.2cm wide, c.3 x as long as broad; pedicels 20-28(—35) mm

Nomenclature

Synonymy: R. duseimatum Balfour f. & Forrest, Notes R.B.G. Edinb. 13: 41 (1920). Type: China, SE Xizang, Dokar La, Mekong/Salween divide, 12000ft, vii 1917, Forrest 16464 (holo. E; iso. K). R. selense Franchet subsp. duseimatum (Balfour f. & Forrest) Tagg in Stevenson (ed.), The Species of Rhododendron 722 (1930). R. selense Franchet var. duseimatum (Balfour f. & Forrest) Cowan & Davidian, Rhododendron Yearbook 6: 152 (1952).

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Rhododendron camelliiflorum Hooker

Shrub to 2 m, epiphytic or growing on rocks. Young growth lepidote. Leaves narrowly elliptic to oblong-elliptic, bluntly acute at the apex, tapering to a shortly rounded base, (53-)60-90(-105) x (16-)20-30(-37) mm, shining dark green above with few, dried-out scales, pale green to brownish beneath with a dense covering of almost contiguous, broadly rimmed scales of which a few are larger and darker than the rest. Inflorescence 1-2-flowered, pedicels densely lepidote. Calyx lobes oblong, rounded at the apex, 5-8 mm, lepidote or not on the surface, fringed with scales. Corolla waxy, with a short, broad tube, white to deep rose, rarely with a whitish or yellowish zone within at the base, lepidote outside, villous within, 14-18(-20) mm, tube 8-10 mm. Ovary 5-10-locular, lepidote, style usually shorter than the stamens. Capsule ovoid, lepidote, tapered to the apex, 7-11(-13) mm

Habitat: Forest and forest margins, cliffs

Distribution: Nepal, India (Sikkim), Bhutan

Altitude: 2750-3650m

Illustrations:

Notes

R. lucidum Nuttall, Hooker's Kew Journ. 5: 363, 1853 (Type: On the mountains of Bootan (i.e. India, Arunachal Pradesh, cf, Ludlow, loc. cit.), beyond the Bhorelli, Booth—holo. K) is based on a plant without flowers or fruits. It is probable that it is merely a variant of R. camelliiflorum.

Nomenclature

Type: Sikkim Himalaya, 9-10000 ft, fl. vii, fr. xii, Hooker (holo. K)

Synonymy: R. sparsiflorum Nuttall in Hooker's Kew Journ. 5:363 (1853). Type: 'Bootan'(i.e. India, Arunachal Pradesh, cf. Ludlow, Trans. Bot. Soc. Edinb. 41:362, 1972), Booth (holo. K). R. cooperi Balfour f., Notes R.B.G. Edinb. 10:91 (1917). Type: Bhutan, Ridang, Angduphorang, 9000 ft, 8 vi 1915, Cooper 3959 (holo. E)

Flags

Occurs in Countries: BT, IN, NP Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: rose, white, yellow

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):138

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Rhododendron campanulatum D. Don

Shrub or small tree, 1.3-4.5m; young shoots glabrous. Leaves ovate to broadly elliptic, 7-14 x 3.8-7.5cm, 1.9-2.5 x as long as broad, apex ± rounded, apiculate, base rounded to cordate, upper surface glabrous when mature, lower surface with a dense fulvous lanate tomentum composed of capitellate to ramiform hairs; petioles 1.5-2.5cm, glabrous. Inflorescence 8-15-flowered; rhachis up to 25mm; pedicels 15-25mm, glabrous. Calyx c.lmm, glabrous. Corolla open-campanulate, white to pale mauve or pink, with ± pronounced purple flecks, 30-50mm. Ovary glabrous. Capsule 20-30 x c.5mm, usually curved.

Notes

The following natural hybrids occur in the wild: i. R. campanulatum x R. arboreum-a specimen from Chankali Lagma, Nepal (Polunin, Sykes & Williams 4113) is presumed to be a hybrid of this parentage. ii. R. campanulatum subsp. aeruginosum x R. mghtii. Shrub, 0.6-2m. Leaves coriaceous, 7-10 x 3.2-5cm,c.2 x as long as broad, apex rounded, base rounded to sub-cordate, upper surface glabrous, lower surface with a compacted reddish-brown indumentum composed of radiate hairs; petioles 0.8-lcm, densely tomentose. Inflorescence 10-12-flowered; rhachis up to 12mm; pedicels 10-15mm, very sparsely tomentose to glabrescent. Calyx c.lmm, glabrous. Corolla campanulate, white to purplish-pink, 30-35mm. Ovary glabrous. Fruit not known. Occurs where the ranges of the two parents overlap, especially in C Bhutan. iii. R. campanulatum subsp .campanulatum x R. w/gM/-a smgle specimen with leaves 11 x 6.2cm but otherwise as in 'ii.? is presumed to be a hybrid with this parentage (Sharma E 219, from Nepal).

Flags

Occurs in Countries: BT, IN, NP Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Tree Fl. Colour: lilac, mauve, pink, purple, rose, white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):372

Rhododendron campanulatum subsp. aeruginosum (Hooker f.) Chamberlain

Leaves 7-9.5cm long (wild specimens), coriaceous, opening with a bluish metallic bloom on the upper surface; corolla lilac or purple.

Habitat: Alpine slopes

Distribution: N India (Sikkim), Bhutan, ? E Nepal

Altitude: 3800-4500m

Notes

All specimens seen of subsp. aeruginosum have small coriaceous leaves and in this respect agree well with the type specimen. However, the characteristic bloom on the upper surfaces of the leaves is usually lost on drying so it cannot be observed on most herbariaum material. I have not seen any specimens from C and E Sikkim or from Bhutan that match W Himalayan specimens in the size of their leaves but there is a series of fruiting specimens, presumed to have been collected in Sikkim (Cave 6719, 6726, 6983; Watt 5245, 5295, 5296), with leaves 7.5-9cm long, but subcoriaceous and with a less thick indumentum than is usual in subsp. aeruginosum. These may be considered as being intermediate between the two subspecies. There is also a series of intermediate plants in cultivation from E Nepal (Spring-Smythe 7, 8, 9, 11, 17, 41, 44). On present evidence therefore, subsp. aeruginosum apparently replaces subsp. campanulatum in the east but there is a zone of overlap.

Nomenclature

Synonymy: R. aeruginosum Hooker f., Rhododendrons Sikkim Himalaya 23, t.22 (1849). Type: Sikkim Himalaya, Laochun, Lachung, Hooker (E). R. campanulatum D. Don var. aeruginosum [Hooker f. ex] Cowan & Davidian, Rhododendron Yearbook 4: 168 (1949).

Rhododendron campanulatum subsp. campanulatum

Leaves 9.5-14cm long, subcoriaceous, without a metallic bloom; corolla whitish to pale rose or lilac.

Habitat: Mixed forest, scrub, etc.

Distribution: N India (Kashmir to W Sikkim), Nepal, Bhutan

Altitude: 2700-3500m

Illustrations:

  • Bot. Mag. 66: t.3759 (1840)
Nomenclature

Type: C Nepal, Gossaingsthan, Wallich 756a (iso. E)

Synonymy: R. nobile Wallich, pro parte, nomen nudum.

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Rhododendron campylocarpum Hooker f.

Shrub or small tree, 1—4(—6.5)m; young shoots usually with a few short stipitate glands. Leaves orbicular to elliptic, 3.2-10 x 1.5-5cm, 1.1-2.5 x as long as broad, apex rounded and apiculate, base ± cordate, upper and lower surfaces glabrous when mature, rarely with a few glands at base below; petioles 0.5-2.2cm, stipitate-glandular, at least when young. Inflorescence 3 —10(—15)-flowered; rhachis 3-5mm, rarely up to 20mm; pedicels 10-35mm, stipitate-glandular. Calyx 3-5mm, stipitate-glandular, lobes rounded. Corolla campanulate, pale to sulphur yellow, sometimes tinged with red in bud, with or without a basal blotch, 25-40mm. Ovary densely stipitate-glandular; style glabrous or glandular for up to one third of its length. Capsule 13-20 x 4-7mm, curved.

Flags

Occurs in Countries: BT, CN, IN, MM, NP Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Tree Fl. Colour: red, yellow

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):263

Rhododendron campylocarpum subsp. caloxanthum (Balfour f. & Farrer) Chamberlain

Habitat: Forest margins, Rhododendron thickets, open places

Distribution: NE Upper Burma and adjacent provinces of China (SE Xizang & W Yunnan)

Altitude: 3000-4300m

Notes

Apparently intergrading with subsp. campylocarpum though probably entirely replacing it in the eastern part of the range of the species. Some forms of subsp. caloxanthum have a marked glaucous bloom on the lower surface of the leaves. These have been referred to R. telopeum. This character is difficult to see in dried material and there are plants from the western part of the range of subsp. campylocarpum that also have glaucous leaves. It therefore seems likely that they are no more than local habitat forms, perhaps showing a response to more exposed conditions. A specimen from SE Xizang, Ludlow, Sherriff & Elliot 13756, is a hybrid of R. campylocarpum, possibly with R. stewartianum as the other parent. R. campylocarpum also hybridises with R. wardii (q.v.) where the ranges of the two species overlap.

Nomenclature

Synonymy: R. telopeum Balfour f. & Forrest, Notes R.B.G. Edinb. 13: 61 (1921) Type: China, SE Xizang, Tsarong, Salween/Kiu-chiang divide, vii 1919, Forrest 18963 (holo. E; iso. K). R. caloxanthum Balfour f. & Farrer, Notes R.B.G. Edinb. 13: 238 (1922). Type: NE Burma, Chimili, 12000ft, 18 v 1919, Farrer 837 (holo. E). R. campylocarpum Hooker f. subsp. telopeum (Balfour f. & Forrest) Chamberlain, Notes R.B.G. Edinb. 36: 116 (1978).

Rhododendron campylocarpum subsp. campylocarpum

Habitat: Open forests, stony slopes

Distribution: Nepal, N India (Sikkim, Arunachal Pradesh), Bhutan, China (S Xizang)

Altitude: 3000-4600m

Illustrations:

  • Bot. Mag. 83: t.4968 (1857)
  • Gard. Chron. 85: 319 (1929)
Notes

Several specimens from Fuchuan, SW of Weixi in NW Yunnan are technically referable to subsp. campylocarpum though they have leaves that are relatively small and which sometimes have rounded bases. These might be part of a stabilised hybrid population with subsp. caloxanthum and R. selense s.l. as putative parents, especially as this locality is outside the normal range of subsp. campylocarpum. These specimens are as follows: McLaren D 231; Rock 16980, 16996, 17011, 17012, 17019, 18353, 18373, 18393.

Nomenclature

Type: Sikkim, 11 —14000ft, Hooker (holo. K; iso. E)

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Rhododendron campylogynum Franchet

Creeping, prostrate or decumbent shrublet up to 60 cm (-1 m), more rarely an erect or ascending shrub. Young growth sparsely lepidote, glabrous or pubescent. Leaves obovate or narrowly elliptic, obtuse or rarely subacute at the apex, tapered to the base, (10-)14-25(-34) x (4-)7-12 mm, dark green and sparsely pubescent along the midrib above, papillose and often whitish or silvery beneath, glabrous and with distant, deciduous scales. Inflorescence l-2(-3)-flowered, pedicels sparsely lepidote and pubescent, 25-50 mm, up to 70 mm in fruit. Calyx lobes oblong or obovate, sometimes obscure, usually 4-7 mm, glabrous and usually elepidote. Corolla pink to red or purple, (10-)13-20(-23) mm, tube 7-12 mm, glabrous, elepidote and pruinose outside, sparsely pubescent within the tube. Capsule borne on the accrescent and rigid pedicels, ovoid-cylindric, 7-9 mm, sparsely lepidote.

Habitat: On cliffs and ledges and in moorland and scrub, 2750-4250(-4900) m

Distribution: India (Arunachal Pradesh), ne Burma, China (N, NW, W, C & SW Yunnan, S & SE Xizang)

Illustrations:

Notes

A variable species as to leaf size and shape and corolla colour and size. None of the variation is either correlated or geographically significant.

Nomenclature

Type: China, Yunnan, in rupibus graniticis montis Tsang chan supra Tali, 14 vi 1884, Delavay (holo. P.—n.v.)

Synonymy: R. caeruleo-giaucum Balfour f. & Forrest, Notes R.B.G. Edinb. 13:34 (1920). Type: China, SE Tibet, Tsarong, Salween/Kiu chiang Divide, vii 1919, Forrest 19181 (holo. E). R. cremastum Balfour f. & Forrest, op. cit.: 39. Type: China, NW Yunnan, Mekong/Salween Divide, vii 1917, Forrest 14266 (holo. E). R. glauco-aureum Balfour f. & Forrest, op. cit.: 46. Type: China, Yunnan, Shweli/Salween Divide, vii 1918, Forrest 17544 (holo. E). R. charopoeum Balfour f. & Forrest, op. cit.: 245 (1922). Type: NE Burma, Chawchi pass, 11-13000 ft, Farrer 1670 (holo. E). NOTES RBG EDINB. 39 (1) R. damascenum Balfour f. & Forrest, op. cit.: 254. Type: China, NW Yunnan, Se la, Soutie (holo. E). R. myrtilloides Balfour f. & Kingdon Ward, Notes R.B.G. Edinb. 13:276 (1922). Type: NE Burma, ridge of Naung chaung in Nwai Divide, 15000 ft, 15 vii 1914, Kingdon Ward 1785 (holo. E). R. cerasiflorum Kingdon Ward, Gard. Chron. 93:277 (1933) nomen nudum. R. rubriflorum Kingdon Ward, Rhodo. Assoc. Yearb. Suppl. 240 (1934) nomen nudum. R. campylogynum var. celswn Davidian, Rhodo. Yearbook 8:83 (1954). Type: China, Yunnan, eastern flank of Tali range, 11-12000 ft, Forrest 4151 (holo. E). R. campylogynum var. charopoeum (Balfour f. & Forrest) Davidian, loc. cit. R. campylogynum var. cremastum (Balfour f. & Forrest) Davidian, loc. cit. R. campylogynum var. myrtilloides (Balfour f. & Kingdon Ward) Davidian, op. cit.: 84.

Flags

Occurs in Countries: CN, IN, MM Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: purple, red

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):145

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Rhododendron camtschaticum Pallas

Prostrate or low shrub (usually less than 20cm high), much branched, deciduous or evergreen, the dry bud-scales ± persistent. Leafy shoots from separate buds below the inflorescences; leaves ± sessile, obovate or spathulate, 10-60 x 4-22 mm, base cuneate, apex rounded with a glandular apiculum, serrulate, with marginal cilia and pubescent on the veins below, reticulation of veins evident. Inflorescence buds terminal, opening to produce a 1-3-flowered raceme, the peduncle bearing leafy bracts, often with glandular hairs as well as cilia. Calyx lobes oblong, 8-18 X 4-5 mm, obtuse, margins and back with cilia and glandular hairs. Corolla rose-purple (rarely white) with darker spots, ± rotate, pubescent outside or glabrous, c.20-25 mm long, tube c.7 mm long, the division between the lower pairs of lobes reaching to the base of the tube. Stamens 10, unequal in length, the largest ± equalling the corolla; filaments hairy below. Ovary ovoid, c.6 mm long, pubescent, 5-locular; style curved, pubescent near the base. Capsule ovoid, c.lOmm long, pubescent.

Flags

Occurs in Countries: JP, RU, US Subgenus: Therorhodion Habit: Non-Tree Fl. Colour: white

Philipson, W.R. & Philipson, M.N. (1986) A Revision of Rhododendron III. Subgenera Azaleastrum, Mumeazalea, Candidastrum and Therorhodion. Notes from the Royal Botanic Garden Edinburgh 44(1):19

Rhododendron camtschaticum subsp. camschaticum

Foliage on vegetative shoots without glandular hairs (or these very sparse); corolla lobes pubescent on the outside and with ciliate margins.

Distribution: Japan (N Honshu, Hokkaido), USSR (S & E Kamtschatka, Kuriles Islands), USA (Aleutian Islands and S Alaskan coast).

Rhododendron camtschaticum subsp. glandulosum (Small) Hulten

A lower growing plant with narrower corolla lobes. The leaves of the vegetative shoots are distinctly glandular-hairy and the outer surface of the corolla lobes is glabrous (or virtually so) and margins are not ciliate.

Distribution: USSR (Siberia north of Okhotsk to the Bering Strait), USA (W Alaska - Seward Peninsula and lower Yukon River valley)

Notes

Over most of the range of the species these two subspecies are morphologically distinct and have separate geographical distributions, However, intermediate forms occur in the zone where the two subspecies meet (see Hulten, op. cit.).

Nomenclature

Synonymy: Therorhodion glandulosum Small, N. Amer. Fl. 29(1):45 (1914). Type: USA, Alaska, foot of Kigluiak Mountain, nr Ooglak Bay, Imurak Basin, n.v. Rhododendron glandulosum (Small) Hutchinson in Stevenson (ed.), The Species of Rhododendron 190 (1930).

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Rhododendron canadense (L.)Torrey

Rhizomatous shrub to lm tall; bark reddish brown to grey, smooth to very slightly longitudinally grooved and flaking; young twigs pale to reddish brown, often with a pink tinge, usually glaucous, sparsely covered with multicellular eglandular and shorter gland-headed hairs, moderately to densely covered with short unicellular hairs; new foliage shoots arising from axillary buds associated with foliage leaves of previous year's shoot (i.e. below terminal bud), and some terminal buds. Vegetative bud scales moderately to densely unicellular-pubescent abaxially and often with scattered multicellular gland-headed and eglandular hairs, especially near apex or along midvein, moderately to densely unicellular-pubescent adaxially; margin fringed with unicellular hairs, the lowermost scales often with aristate apices or rudimentary blades. Leaves deciduous, dull bluish green (glaucous) to rarely dark green adaxially, pale to whitish green abaxially, turning red in autumn, alternate (with internodes becoming more closely spaced towards tip of shoot). Blade membranaceous to char-taceous, elliptic or oblong to obovate, 1-8.3 x0.4-3cm; base cuneate or acute to rounded, apex acute to rounded, usually with a short mucro; midvein strongly raised and prominent abaxially, the secondary veins flat to slightly raised abaxially; adaxial surface, including midvein, sparsely to moderately covered with short unicellular hairs and multicellular eglandular and gland-headed hairs; abaxial surface, including midvein and higher order veins, moderately to densely covered with short unicellular hairs and moderately covered with multicellular eglandular and gland-headed hairs, the eglandular hairs of midvein larger than those of higher order veins and lamina; margin entire, revolute to less commonly plane, fringed with multicellular eglandular hairs and with inconspicuous unicellular hairs; petiole l-12mm long, moderately to densely unicellular-pubescent, and with scattered multicellular eglandular and gland-headed hairs, the base of petiole slightly expanded at point of attachment. Flower buds terminal (rarely also from axillary buds just below terminal bud), larger than, but otherwise ± similar to, vegetative buds, more frequently densely unicellular-pubescent. Flowers appearing before or occasionally with the leaves; inflorescence an umbellate raceme of 3-9 flowers. Pedicels 3-10mm long, usually glaucous, usually sparsely covered with multicellular gland-headed hairs, and lacking to densely covered with unicellular hairs. Calyx lobes broadly subovate to triangular-ovate, 0.4-1.5 x 0.7-1.6mm; apex rounded; margin fringed with multicellular gland-headed and/or eglandular hairs, and unicellular hairs; adaxial surface glabrous; abaxial surface usually glaucous, glabrous to densely unicellular-pubescent, often with scattered multicellular gland-headed hairs. Corolla rose-purple to pink, or rarely white, unspotted to red-spotted on upper 3 lobes, fragrant, strongly zygomorphic, clearly 2-lipped due to the very extensive fusion of the upper 3 lobes contrasting with the 2 elongate and widely divergent lower lobes, the tube essentially lacking due to deep division between 2 lower lobes and between lateral and lower lobes; upper corolla lobe 0.3-0.8 x 0.25-0.5cm; lateral lobes 1.2-2.2 x 0.25-0.4cm (closely fused with upper lobe); lower lobes 1.2-2.2 x 0.25-0.6cm (± free); outer and inner surfaces of corolla glabrous to occasionally with few scattered multicellular gland-headed hairs. Stamens 10, slightly declinate to ± straight, variable in length, 0.9-2cm long, exserted (due to deeply cut corolla); filaments glabrous distally, becoming densely covered with flattened unicellular hairs proximally. Ovary L7-3mm long, densely covered with multicellular gland-headed and eglandular hairs and unicellular hairs; style slightly declinate, 1.1-2.2cm long, glabrous to unicellular-pubescent near base, often glaucous. Capsules ovoid to nearly cylindrical and curved near the base, slightly grooved, 0.7-1.7x0.3-0.6cm, often glaucous, moderately covered with multicellular gland-headed and eglandular hairs and densely covered with short unicellular hairs. Seeds brown, flattened ellipsoid, 1-2.7x0.4-1.3mm; testa tightly appressed to body, with cells at each end elongated and expanded, forming a flat tail 0.3-0.9mm long, the cells covering central portion of body elongate and non-bulging, those along margin expanded and flattened (in plane parallel to compression of seed body), forming an irregular wing-like fringe connecting the tails. Cotyledons lacking multicellular hairs and with venation represented by rnidvein and one (or very few) poorly developed secondary veins. 2´ = 52 (Sax, 1930).

Habitat: In moist to dry coniferous or deciduous forests, thickets, open rocky areas, lake margins, bogs, and swamps

Distribution: Distributed from Newfoundland and Quebec, south to eastern Pennsylvania and northern New Jersey.

Altitude: 0-1900m

Illustrations:

Notes

Rhododendron canadense is a very distinctive species most closely related to R. vaseyi; see discussion following the latter species. Although originally described as the genus Rhodora (Linnaeus, 1762), its close relationship to Rhododendron has long been recognized (see Rehder, 1921a; Sleumer, 1949, 1980; Wood, 1961).

The artificial (and infertile) hybrid between Rhododendron canadense and R. molle (Blume) G. Don subsp. japonicum (A. Gray) K. Kron is referred to as R. fraseri W. Watson (Gard. Chron., ser. 3, 67: 225, 1920). Representative specimens of this entity include: Fraser s.n., 1929 (A); C.E.K. C.K.A., Arnold Arbor. #15359 (A); Rehder s.n., 29 iii 1920 (A); E.J.P., Arnold Arbor. #15359-1 (A).

Flags

Occurs in Countries: JE Altitude Ranges: 0 - 1,000m: 1,000 - 2,000m Subgenus: Pentanthera Habit: Non-Tree Fl. Colour: pink, red, white

Judd, W.S. & Kron, K.A. (1995) A Revision of Rhododendron VI. Subgenus Pentanthera (Sections Sciadorhodion, Rhodora and Viscidula). Edinburgh Journal of Botany 52(1):30

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Rhododendron canescens (Michaux) Sweet

Shrub or small tree to 6m tall, usually non-rhizomatous; young twigs red-brown, sparsely to densely covered with unicellular hairs and multicellular eglandular hairs, occasionally with only unicellular hairs, or with unicellular hairs and multicellular gland-tipped hairs, rarely glabrous. Vegetative bud scales densely covered with unicellular hairs abaxially; margin unicellular-ciliate or glandular. Leaf blade membranaceous, ovate or obovate to elliptic, (4.7-)5.9-8.5(-9.8) x (1.4-)1.9-2.8(-3.6)cm; base acute to oblique; apex acute to obtuse, often mucronate; adaxial surface sparsely to densely covered with unicellular hairs, or also with multicellular eglandular hairs, occasionally only with multicellular eglandular hairs, rarely with unicellular hairs and multicellular gland-tipped hairs, the midvein densely covered with unicellular hairs; abaxial surface sparsely to densely covered with unicellular hairs, rarely also with multicellular eglandular hairs, or glabrous, the midvein densely covered with unicellular hairs and multicellular eglandular hairs, or rarely with multicellular gland-tipped hairs or only unicellular hairs; margin entire, rarely minutely serrulate, ciliate with multicellular eglandular hairs, rarely with a few multicellular gland-tipped hairs at the base of the blade; petiole (0. l-)0.2-0.4(-0.5)cm long, sparsely to densely covered with unicellular hairs and multicellular eglandular hairs, occasionally with unicellular hairs and multicellular gland-tipped hairs, rarely with only unicellular hairs. Flower bud scales chestnut brown; abaxial surface densely covered with unicellular hairs; margin unicellular-ciliate, occasionally with both unicellular hairs and glands. Flowers appearing before or with the leaves; inflorescence a shortened raceme of 6 to 19 flowers. Pedicels (0.4-)0.5-l .0(-l .3)cm long, sparsely to densely covered with unicellular hairs and multicellular eglandular hairs, occasionally with unicellular hairs and multicellular gland-tipped hairs, rarely with all three types of hairs. Sepals less than 0.1-0.2(-0.4)cm long, often varying in length on the same flower; margins setose, occasionally also with multicellular gland-tipped hairs, or only glandular-fimbriate; abaxial surface densely covered with unicellular hairs, or also with multicellular eglandular hairs, occasionally with unicellular hairs and multicellular gland-tipped hairs, rarely with all three types of hairs. Corolla pink, or the tube pale to deep pink and the lobes pale pink to white, occasionally white or rose to deep pink throughout, fragrance musky-sweet, the tube longer than the limb and gradually expanding into it; upper corolla lobe (0.7-)0.8-l .3(-l .5) x (0.6-)0.7-l .0(-l .4)cm wide; lateral lobes (0.8-)1.0-1.5(-2.0) x (0.3-)0.5-0.8(-1.0)cm; corolla tube (1.3-)1.5-2.0(-2.6) long, (0. l-)0.2-0.3(-0.4)cm wide at base; outer surface of corolla densely covered with unicellular hairs and sparsely to densely covered with multicellular gland-tipped hairs that occasionally continue up the corolla lobes; inner surface of corolla sparsely to densely covered with terete or rarely flattened unicellular hairs. Stamens (3.1-)4.4-5.7(-6.4)cm long, with dense terete or flattened unicellular hairs on proximal (0.0-)2.0-3.1(-4.1)cm of filament, exserted (1.7-)2.5-3.6(-4.5)cm beyond throat of corolla. Style (3.7-)4.4-5.7(-6.8)cm long, exserted (2.0-)2.7-3.9(-4.8)cm beyond throat of corolla, with dense unicellular hairs on proximal (0.0-)0.7-2.0(-3.3)cm; stigma 0. l-0.2cm wide. Ovary 0.3-0.4(-0.5)cm long, 0. l-0.2(-0.3)cm wide at the base, densely covered with unicellular hairs and multicellular eglandular hairs, occasionally also with multicellular gland-tipped hairs, or with unicellular hairs and multicellular gland-tipped hairs; the multicellular hairs may cover the unicellular hairs or may only occur on the ribs of the ovary; the nectary is crowned with a dense ring of unicellular hairs. Capsules (1.2ó)1.5ó2.1(ó2.5) x 0.3-0.5cm wide, narrowly ovate to cylindric, moderately to densely covered with unicellular hairs and sparsely to moderately covered with multicellular eglandular hairs. Seeds pale to dark chestnut brown, ovate or elliptic to fusiform, (1.2-) 1.6-2.5(-3.0) x (0.3-)0.5-0.8(-l.l)mm, body (0.6-)0.8-1.2(-1.4) x (0.1-)0.3-0.5(-0.6)mm; testa expanded and dorsiventrally flattened, surrounding the body, with both elongate and short cells scattered throughout the testa, the short eels more common in the expanded portion of the testa, with tapering end-walls

Habitat: River bottoms and stream banks, low flatwoods, dry clearings and open woods.

Distribution: Tennessee and southern North Carolina, south along the Coastal Plain and Piedmont to peninsular Florida, west to eastern Texas and Oklahoma, north to Union Co., Illinois (Fig. 27).

Altitude: 0-500m

Notes

Chromosome number: In = 26 (Janaki-Ammal et al., 1950; Li, 1957)

Flowering from March to April; occasionally as late as June or July.

Rhododendron canescens is similar morphologically toR.prinophyHum mAR. periclymenoides, and these three variable species have been considered difficult to identify by previous workers (Rehder, 1921; Skinner, 1955,1961; King, 1977a, b, 1980; Galle, 1985). In addition, hybridization can occur where the habitats and geographic ranges of these species overlap. All three species have pink-white corollas, and flower before or with the leaves in the spring. In general, the corolla tube expands gradually into the limb, but in R. canescens the limb is slightly more abruptly expanded than in R. periclymenoides orR. prinophyllum. This character is difficult to measure on herbarium material, and, in this group, is continuously variable. In the past, the characters used to distinguishR. canescens fmmR. periclymenoides were primarily those of the indumentum of the corolla tube (Rehder, 1921; Skinner, 1955,1961). Rhododendron canescens has multicellular gland-tipped hairs on the outer surface of the corolla tube, whereas most populations of R. periclymenoides have multicellular eglandular hairs. However, there are glandular forms of R. periclymenoides. These were attributed to hybridization by Skinner (1961). Other characters used to distinguish R. canescens from R. periclymenoides include the following: dense unicellular pubescence of the abaxial surface of the leaves (Porter, 1889a; Rehder, 1921; Skinner, 1961) and dense unicellular pubescence of the abaxial surface of the bud scales (Rehder, 1921; Lawrence, 1954; Skinner, 1961; Galle, 1968). Galle (1968) noted that R. periclymenoides is rarely white, while R. canescens often has at least some white on the corolla limb, if not also on the corolla tube. The gradually expanding corolla tube and the less dense unicellular pubescent condition of the leaves of some individuals of R. prinophyllum have led to some confusion in separating it from R. periclymenoides. These two species are more northern in their distribution than R. canescens and are sympatric throughout much of their range. Although Rehder (1921) recognized these as distinct species, Weigand (1924) commented that one species graded into the other, and thus recognized R. prinophyllum as a variety of R. periclymenoides [ R. nudiflorum (L.) Torrey var. roseum (Lois.) Weigand]. Lawrence (1954) discussed the differences between the two species, and distinguished R. prinophyllum from R. periclymenoides on the following characters: unicellular pubescent bud scales vs. usually glabrous bud scales, blue-green adaxial leaf surface vs. bright green surface, 'spicy9 fragrance vs. sweet fragrance, multicellular gland-tipped hairs on the surface of the corolla vs. multicellular eglandular hairs, shorter stamens and the fruit with multicellular glandular hairs vs. longer stamens and the fruit with multicellular eglandular hairs. Skinner (1961) also reported that plants of R. prinophyllum were generally non-stoloniferous, whereas those of R. periclymenoides were often stoloniferous. 306 EDINB. J. BOT. 50(3) Fig. 27. Distribution of Rhododendron canescens. The results of principal component analysis of 117 OTUs using 26 floral characters (see Table 5, Fig. 28) show that R. prinophyllum is morphologically the most distinctive of the three pink to white early flowering species. The characters which influenced the first principal component were primarily those of floral indumentum and size. Among the floral characters influencing the first component, sepal margin and pedicel pubescence were the most heavily factored. In R. canescens and R. periclymenoides the sepal margin is usually setose, whereas the sepals of R. prinophyllum usually have at least some multicellular gland-tipped hairs along the margin. In addition, the pedicels of R. prinophyllum are more often glandular than those of R. canescens or R. periclymenoides. It is interesting to note that when these indumentum characters are considered individually, R. prinophyllum is usually more distinct from R. periclymenoides, with which it is often sympatric, than it is from the allopatric R. canescens. Even though the range of morphological variation within each species overlaps to some extent, the overlap is consistently less between R. prinophyllum and R. periclymenoides than between R. prinophyllum and R. canescens. The delimitation of R. periclymenoides and R. canescens is less definite. These two species are generally allopatric but their geographic ranges overlap as R. canescens extends into the Piedmont and R. periclymenoides is found on the northern Atlantic Coastal Plain. The results of principal component analysis of 88 OTUs using 30 floral and bud-scale characters (see Table 5, Fig. 29) show that these two species are indeed very similar morphologically. The first component is most heavily influenced by corolla size, while the second is influenced most by the stamen length and sepal margin. Rhododendron periclymenoides has a greater percentage of individuals with pedicels lacking unicellular hairs than R. canescens, which always has pedicels with unicellular hairs. While the pedicels of R. canescens and R. periclymenoides usually have multicelluar eglandular hairs, R. canescens also often possesses at least some multicellular gland-tipped hairs on the pedicel. Since the indumentum of the corolla tube has been stressed in previous treatments this character was investigated with respect to its geographical distribution and its occurrence in the principal component analysis plot. The occasional glandular condition of the corolla tube of R. periclymenoides does not correlate with overlap of the geographic ranges of R. canescens and R. periclymenoides. Instead, it occurs sporadically in populations throughout the range of R. periclymenoides, often where R. canescens does not occur. Therefore the glandular condition of some individuals of R. periclymenoides reflects natural variation within the species, and usually does not indicate hybridization with R. canescens. However, the morphological similarity between these two species, whose ranges are primarily allopatric, raises the question of whether they should be considered to be geographical subspecies. This can best be answered by the results of the cladistic analysis (see Phylogenetic Analysis). Rhododendron periclymenoides and R. canescens form a paraphyletic group and therefore it would be phylogenetically misleading to lump both taxa into a single species. Therefore two partially sympatric species are recognized: Rhododendron periclymenoides and R. canescens. The most variable characters of R. canescens are the density of the pubescence of the leaves, flower colour, and, to a lesser extent, bud-scale margins. Plants in southern Georgia, Arkansas and Oklahoma tend to be very densely unicellular pubescent, whereas those individuals in Louisiana and Mississippi tend to be more sparsely unicellular pubescent. The flower colour varies from completely white to dark pink, but these variations do not show any geographical or ecological pattern. The margin of the bud scales is almost always ciliate, except for some populations in central Georgia and South Carolina. In these populations the bud-scale margins are hiixed unicellular-ciliate and glandular. Whereas R. canescens and R. prinophyllum are almost completely allopatric, the geographic range of R. canescens overlaps with that of R. periclymenoides. Rhododendron canescens is generally found in wetter habitats than R. periclymenoides, but this is not always the case, especially in the upper Piedmont. Rhododendron canescens hybridizes with several species that occur within its geographic range.

Nomenclature

Synonymy: Azalea canescens Michaux, Fl. Bor.-Amer. 1: 150 (1803). Type: juxta rivulos Carolinae inferioris. A. Michaux s.n. (lecto. designated here, P-MICHX; IDC #6411,36.1.4). Azalea nudiflora var. bicolor Aiton, Hort. Kew. 1: 203 (1789). A. bicolor (Aiton) Pursh, Fl. Am. Septentr. 1: 153 (1814). Rhododendron bicolor (Aiton) Sweet, Hort. Brit. 344 (1830). Type: n.v. Azalea rosea Lois, in Duhamel, Traite Arb. Arbust. ed. 2, 224: 64 (1812), nom. illeg.; Rhododendron roseum (Lois,) Rehder, Monogr. Azaleas 138-139 (1921), nom. illeg.; R. nudiflorum (L.) Torr. var. roseum (Lois.) Weigand in Rhodora 26:1-5 (1924), nom. illeg. Type: as for A. canescens Michaux. Azalea Candida Small in Bull. Torrey Bot. Club. 28: 360 (1901). Rhododendron candidum (Small) Rehder, in Bailey, Stand. Cycl. Hort. 5: 2945 (1916). R. canescens (Michaux) Sweet var. candidum (Small) Rehder, Monogr. Azaleas. 146 (1921). Azalea canescens var. Candida (Small) Ashe in J. Elisha Mitchell Sci. Soc. 38: 91 (1922). Type: Georgia, Lowndes Co.: along Withlacoochee River, about Valdosta. 6-12 vi 1895. /. K. Small s.n. (holo. NY; iso. A, NY). Rhododendron canescens f. subglabrum Rehder, Monogr. Azaleas 145 (1921). Type: Mississippi, Hinds Co.: Jackson, 15 iv 1915. T. G. Harbison 16 (lecto. A; isolecto. NCU).

Flags

Altitude Ranges: 0 - 1,000m Subgenus: Pentanthera Habit: Tree Fl. Colour: pink, rose, white

Kron, K.A. (1993) A Revision of Rhododendron Section Pentanthera. Edinburgh Journal of Botany 50(3):302

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Rhododendron capellae Kores

Terrestrial, erect, branching shrub, c.50cm. Twigs erect, slender, rounded, 1–2mm in diameter, tips laxly scaly, glabrescent below. Leaves crowded especially at the tips of the new shoots. Blade 8–15 x 3–6mm, elliptic or obovate; apex abruptly acuminate; margin thickened and a little paler than the lamina, sub-crenulate where impressed scales are, or have been, slightly or not revolute; base acutely tapering, dark green above, lighter green below, sub-densely scaly on both sides initially, glabrescent and shiny above at maturity, persistently scaly below. Scales the marginal zones entire and somewhat irregular, impressed with thickened centres. Mid-vein impressed above, raised beneath; lateral veins obscure. Petiole 2–3mm, slender, flattened, laxly scaly. Outer bracts 6–10mm, ovate-acuminate, subulate or apiculate, laxly scaly and very laxly hairy; inner bracts broader, obovate, apiculate and very laxly scaly outside. Inflorescence of solitary flowers or in twos. Flowers half-hanging to hanging. Pedicels 12–15mm, slender, scaly. Calyx membranous, with 5 broadly triangular lobes 0.5–1mm. Corolla 25–30mm, tubular, slightly dilated near the mouth, bright red, glabrous inside; tube cylindrical, 17–20 x 3–4 x 5–7mm, slightly curved, laxly scaly outside, glabrous inside; lobes 6–7 x 4–6mm, half-spreading, broadly obovate, scaly proximally outside. Stamens almost equal in length, exserted to c.3mm; filaments linear, laxly hairy in the proximal ¼, glabrous distally; anthers obovate, c.1.5 x 1mm. Disc glabrous except for a minutely hairy upper margin. Ovary cylindrical-conical, densely covered with long white hairs and sub-densely scaly, c.5 x 1.5mm, tapering distally; style just shorter than the corolla tube with a few hairs at the base, glabrous distally; stigma club-shaped-globose.

Habitat: Sub-alpine shrubbery

Distribution: Papua New Guinea, West Sepik Province, Star Mts, summit region of Mt Capella

Notes

Named after the mountain on which it was found.

Transferred from Pseudovireya (sensu Sleumer 1966) as the bract margins are scaly, not hairy. At present known only from the type collection and not in cultivation. Said to be closely related to R. pulleanum (Kores 1978) but R. capellae has much less warty twigs, much longer, subulate outer bracts and an ovary which is both hairy and scaly. It would appear to be closer to R. womersleyi but differs in the more slender subulate bracts in addition to the characters used in the key.

Nomenclature

Type: Croft & Hope LAE 68056, 29 May 1975. Papua New Guinea, W Sepik Province, Star Mts, summit region of Mt Capella (LAE, A, BRI, CANB, CANU, E, K, L).

Flags

Occurs in Countries: PG Subgenus: Vireya Habit: Non-Tree Fl. Colour: red

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:150

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Rhododendron capitatum Maximowicz

Compact and rounded shrub to 1-5 m. Leaves (7-)10-18(-22) x(3-)5-9 mm, elliptic or oblong-elliptic, apex rounded, emucronate, base broadly cuneate, undersurface pale brown with darker speckling, the bicolorous scales contiguous or discontiguous, colourless to straw-coloured with pale golden centres and tan to dark amber with darker centres, usually either equal in number or the pale scales predominating. Inflorescence 3-5-flowered, pedicel 1-3 mm, pilose or lepidote. Calyx variable, often with unequal membranous lobes up to 6 mm, pilose or lepidote at base, margins ciliate. Corolla pale lavender to bluish purple or deep purple, broadly funnel-shaped, pubescent in the throat and sometimes minutely so on the tube outside, 10-15 mm, tube 3-5 mm. Stamens 10, filaments pubescent towards the base. Ovary lepidote, style 6-13 mm, usually slightly exceeding the stamens, glabrous or pubescent towards the base. Capsule ovoid, 5-6 mm, lepidote.

Habitat: Forests, mountainsides, moist meadows

Distribution: China (N Sichuan, Quinghai, Gansu, Shaanxi)

Altitude: 3000-4300m

Notes

Similar to R. nitidulum (p. 98), with which it possibly intergrades (cf. Philipson & Philipson, 1975, p. 58)

Nomenclature

Type: China, Kansu, Przewalski 22 (holo. LE)

Flags

Occurs in Countries: CN Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: lavender, purple

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):107

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Rhododendron carneum Hutchinson

Free-growing shrub up to 1 m. Young growth not loriform-setose. Leaves narrowly elliptic, rarely obovate, tapered to the base and the acute apex, 50-110 x 30-40 mm, dark green and persistently lepidote above, brownish or greyish beneath with scales about their own diameter apart. Inflorescence 2-4-flowered; pedicels lepidote. Calyx unequally 5-lobed, lepidote, the margins loriform-ciliate. Corolla pink all over (sometimes very faintly so), funnel-shaped, 40-50 mm, the tube c. 30 mm, pubescent at the base and moderately lepidote all over the surface outside. Stamens 10, filaments pubescent towards the base. Ovary densely lepidote, tapering into the lepidote style. Capsule lepidote, oblong, up to 20 mm.

Distribution: Know only in cultivation

Notes

From the available material, which is all cultivated, R. carneum appears to be reasonably distinct. However, its status must remain doubtful until wild material is collected.

Nomenclature

Type: Described from a plant cultivated at Kew, said to originate in the northern Shan States of Burma (holo. K)

Flags

Subgenus: Rhododendron Habit: Non-Tree

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):55

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Rhododendron carrii Sleumer

Shrub. Twigs rounded, tips glabrous or very laxly scaly; internodes 2.5–9cm. Leaves 3–4 together in pseudo­whorls at the upper 3–4 nodes. Blade 40–60 x 25–55mm, ovate to sub-ovate-rounded; apex broadly and shortly acuminate, obtuse; margin entire, flat; base distinctly sub-auriculate, cordate, sessile or nearly so, superficially glabrous, but laxly covered with minute irregularly stellate scales beneath leaving a minute spot where the slightly impressed centre was. Mid-vein flat or slightly impressed above, grooved in the proximal ½, thick and very prominent beneath proximally, less so distally; lateral veins c.10 per side, 2–3 of them from the base of the blade, the others from the mid-vein, all curved-ascending and anastomosing near the edge, prominent on both sides, reticulation dense and clearly visible especially beneath. Petiole c.1 x 1.5mm. Bracteoles linear. Inflorescence a 4–5-flowered umbel. Pedicels 13–25mm, thick, sub-densely to laxly thin-scaly, thickened at apex. Calyx c.2mm in diameter, oblique, membranous, shortly, obtusely 5-lobed to 1mm, shortly fringed. Corolla trumpet-shaped, white; tube 55–60 x c.3.5 x c.7mm, slightly curved, dilated gradually upwards, laxly sub-stellately scaly outside, with dense retrorse hairs proximally, distally more laxly so with spreading hairs, glabrous below the mouth; lobes 12–15 x 10–15mm, spreading, rounded-obovate, glabrous on both sides. Stamens a little exserted; filaments narrow-linear, densely hairy at the base, more laxly and patently so in the middle, glabrous distally; anthers 2.8–3 x 1mm, oblong, base obtuse. Disc densely short-hairy especially above. Ovary c.10 x 2mm, elongate-conical, densely covered with appressed yellowish hairs and laxly with scales which tend to be hidden by the hairs, gradually tapering distally; style 55–65mm, exserted, laxly hairy and scaly at the base for c.5mm only, glabrous distally; stigma thick-conical, crenulate.

Distribution: Papua New Guinea, Mt Victoria, NW of ‘The Gap’. Epiphytic on an open hillside

Altitude: Around 2440m

Notes

Named after the collector, Cedric Carr, orchid enthusiast and prolific plant collector who spent many years in SE Asia.

Nomenclature

Type: Carr 15266, 27 Jan. 1936. New Guinea (SE), Central District, ascent to Mt Victoria, Main Range NW of ‘The Gap’, 2440m (BM, A, K, SING).

Flags

Occurs in Countries: PG Altitude Ranges: 2,000 - 3,000m Subgenus: Vireya Habit: Non-Tree Fl. Colour: white

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:178

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Rhododendron carringtoniae F.Muell.

Shrub to 5m. Twigs c.4mm in diameter, rounded, tips densely covered with thin brown scales; internodes 2–3cm. Leaves 3–5 together in tight pseudowhorls, sometimes with one or two much smaller leaves, also recorded as spiral. Blade 40–80 x 25–45mm, obovate to elliptic-obovate, apex rounded or obtuse; margin slightly or not recurved; base broadly tapering but the extreme base rounded or truncate; glabrescent above when fully mature, sub-densely to laxly scaly beneath. Scales thin, marginal zone persistent, shallowly and irregularly dentate; centre small, impressed. Mid-vein raised above but grooved proximally for a few millimetres, impressed distally, strongly prominent beneath, but less so towards the apex; lateral veins 6–8 per side, often forked before the edge, anastomosing both among each other and with the stronger veins, laxly reticulate, prominent on both sides. Petiole 2–6 x 2–5mm, somewhat flattened and weakly grooved above, scaly. Flower buds to 40 x 20mm, elongate-ovate, imbricate, yellow-brown, smooth. Bracts to 25 x 15mm, sub-circular to obovate-spathulate, scaly outside and not or only laxly shortly hairy. Inflorescence at first an erect umbel of 5–6 flowers, the tubes closely held together by the bracts, later the flowers spreading and the umbel becoming open. Bracteoles linear. Pedicels c.2 x 5–8mm, sub-densely scaly. Calyx c.2mm in diameter, rim-like, membranous, irregularly and very shortly 5-dentate, fringed. Corolla trumpet-shaped, white, powerfully and sweetly scented; tube 50–70 x 4–4.5 x 5.5–6mm, cylindrical, slightly curved, sub-densely scaly outside, inside with short spreading hairs proximally becoming glabrous above the middle; lobes 10–15 x 6–13mm, obovate to broadly elliptic- circular, spreading, very laxly scaly outside, glabrous inside. Stamens exserted to 8mm, arranged all round the mouth; filaments linear, densely covered with spreading hairs below, these gradually thinning to become glabrous distally; anthers 5–7 x 1–1.2mm, sub-obovate-oblong, base of each cell with a distinct spur-like point. Disc densely hairy. Ovary c.10 x 1.5mm, narrowly cylindrical, slightly tapering towards the base, densely covered with yellowish or whitish, forwardly pointing hairs which cover numerous scales, gradually tapering distally; style 55–65mm, hairy and densely scaly apart from the distal 6mm; stigma conical. Fruit narrowly cylindrical, shortly tapering at both ends, with 5 grooves, sub-densely hairy and scaly, c.50 x 6mm. Seeds with very narrow appendages.

Habitat: On open hillsides, along rocky river banks and gorges, mostly terrestrial but occasionally epiphytic.

Distribution: Papua New Guinea, Owen Stanley Range; Central District: Mt Obree, Mt Victoria; Milne Bay District: Mt Dayman, Mt Suckling.

Altitude: 1830-2440m

Notes

Named after Lady Carrington, wife of the British representative in New Guinea, for her interest in the plants of the colony.

Nomenclature

Type: Cuthberson & Sayer s.n. New Guinea (SE), Central District, Mt Obree, 1830–2135m (MEL, K).

Flags

Occurs in Countries: PG Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Vireya Habit: Epiphyte, Non-Tree Fl. Colour: white

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:179

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Rhododendron carstensense Wernham

Shrub. Twigs sub-angular, whitish, smooth, early glabrescent; internodes 7–10cm. Leaves 3–4 together in pseudowhorls. Blade 65–100 x 40–55mm, broadly elliptic, elliptic to obovate-elliptic; apex obtuse to rounded; margin entire, flat; base shortly and broadly tapering, glabrescent above at maturity, sub-densely scaly beneath. Scales small, marginal zone irregularly dentate; centre a little impressed. Mid-vein somewhat impressed above, strongly prominent beneath; lateral veins 8–10 per side, irregular, straight below, curved-anastomosing before the margin, slightly impressed above, hardly prominent beneath, smaller veins laxly reticulate, raised beneath only. Petiole 10–15 x c.2mm, grooved above. Bracts to 40 x 18mm, obovate-elliptic, hairy outside in the middle and with longer and appressed hairs in the lower part on both sides. Bracteoles 30–50mm, filiform, hairy. Inflorescence 6–9-flowered. Pedicels c.5mm, thick, scaly. Calyx minute, oblique, circular, obscurely 5-lobed. Corolla 65–70mm, trumpet-shaped; tube 50–60 x c.3 x c.6mm, cylindrical, hardly widened upwards, glabrous outside, densely hairy inside in the proximal ½; lobes c.17 x 14mm, obovate-sub-circular, glabrous. Stamens somewhat exserted from the mouth; filaments linear, densely hairy to 4/5, glabrous distally; anthers c.6 x 1mm, each cell with a tail-like appendage (1–1.5mm) at the base. Disc sub-glabrous. Ovary c.7 x 1.8mm, elongate-cylindrical, very densely covered with yellowish hairs, gradually tapering distally; style yellowish hairy in the proximal 1⁄3, glabrous distally; stigma thick-obconical.

Distribution: Indonesia, New Guinea (W), Mt Jaya (Mt Carstensz), once collected

Altitude: 1675-2040m

Notes

Named after the mountain on which it was collected.

Not so far recollected and never cultivated. Very similar to R. syringoideum, differing chiefly in the much smaller flowers; it is the older name and would take precedence if the species were amalgamated.

Nomenclature

Type: Kloss B. s.n., 26 Jan. 1913. New Guinea (W), Ascent to Mt Carstensz, 1675–2040m (BM).

Flags

Occurs in Countries: ID Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Vireya Habit: Non-Tree

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:172

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Rhododendron catacosmum [Balfour f. ex] Tagg

Shrub, 1.3—3m; young shoots fulvous-tomentose, setae very few or entirely lacking. Leaves obovate, 8-10 x 4.2-5.5 cm, 1.6-2 x as long as broad, apex rounded, apiculate, base broadly cuneate, upper surface glabrous, lower surface densely fulvous-tomentose, indumentum bistrate, the upper layer loose, dendroid, the lower whitish and compacted; petioles 1-1.5cm, tomentose. Inflorescence 6-9-flowered; rhachis 5-10mm; pedicels 25-35mm, floccose-tomentose. Calyx 15-20mm, cupular, glabrous except for the ciliate margin, lobes shallow. Corolla fleshy, tubular-campanulate, crimson, c.45mm. Ovary densely tomentose. Capsule 20-25 x c.l2mm.

Habitat: Forest margins, rocky slopes

Distribution: China (SE Xizang, NW Yunnan)

Altitude: 3650-4400m

Notes

Closely allied to R. haematodes but generally with larger leaves and calyces. One specimen, Forrest 20908, has the leaf shape and indumentum of R. catacosmum but the setulose young shoots and petioles of R. haematodes subsp. chaetomallum. This may be a hybrid. A specimen, Rock 17016, is intermediate between R. catacosmum and R. coelicum, with the sparsely stipitate-glandular petioles of the latter and the tomentose ovaries and the large calyx of the former. R. catacosmum apparently hybridises with R. citriniflorum (q.v.) and R. temenium.

Nomenclature

Type: China, SE Xizang, Tsarong, Salween/Kiu-chiang divide, NW of Si-chi-to, 13000ft, vi 1922, Forrest 21727 (holo. E).

Flags

Occurs in Countries: CN Altitude Ranges: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: crimson

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):389

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Rhododendron catawbiense Michaux

Shrub, 2—3m; young shoots tomentose though soon glabrescent. Leaves broadly elliptic to obovate, 6.5-11.5 x 3.5-5cm, 1.9-2.3 x as long as broad, apex ± obtuse, base rounded, upper and lower surfaces glabrous when mature though with persistent hair bases below; petioles 2-3cm, ± lanate at first, soon glabrescent. Inflorescence dense, 15-20-flowered; rhachis 20-25mm; pedicels 30-35mm, with a sparse dendroid indumentum. Calyx c.lmm, ± glabrous. Corolla funnel-campanulate, usually lilac-purple, with faint flecks, 30-45mm. Ovary densely rufous-tomentose; style glabrous. Capsule c.20 X 4mm.

Habitat: Rocky slopes, etc.

Distribution: Eastern USA (N Carolina & Virginia)

Altitude: 50-1000m

Illustrations:

Notes

Map in Little, Atlas United States Trees 4: map 118 (1977)

Closely allied to R. ponticum despite the surprising disjunction. Large flowered, large-leaved plants from eastern N Carolina have been referred to forma insularis Coker (in J. Elisha Mitchell Sci. Soc. 34: 76 et sec, t.19, 1919).

Nomenclature

Type: USA in montibus excelsis Carolinae septentrionalis, juxto origine-amnis Catawbe, n.v.

Flags

Occurs in Countries: US Altitude Ranges: 0 - 1,000m: 1,000 - 2,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: lilac

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):316

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Rhododendron caucasicum Pallas

Dwarf shrub, 0.3-lm; young shoots sparsely tomentose. Leaves obovate to elliptic, 4-7.5 x 1.3-3cm, 2.2-3 X as long as broad, apex blunt to apiculate, base cuneate, upper surface glabrous, lower surface with a compacted fawn to brownish tomentum; petioles 0.5-lcm, sparsely velutinous. Inflorescence lax, 6-15-flowered; rhachis up to 35mm; pedicels pilose, 25-30mm in flower, up to 60mm in fruit; perulae usually persistent. Calyx 1 —2mm, pilose. Corolla broadly campanulate, whitish to yellow, sometimes flushed with pink, with greenish flecks, 30-35mm. Ovary densely dendroid-pilose; style glabrous. Capsule 15-20 X c.8mm.

Distribution: NE Turkey & adjacent parts of USSR (Caucasia)

Illustrations:

Notes

A distinctive species though apparently hybridising with R. ponticum (q.v.) and R. smirnowii. The plate accompanying the type description gives a false impression of the species as described here and may be disregarded as there is no direct reference to any of the type specimens cited. Plate 3422 in Bot. Mag. 62 (1835) is a reliable representation of the species as treated here.

Nomenclature

Type: USSR, altere septentrionale Caucasi, in Ossetia inter Tschin et Tschinaga meridiem versus; postea in Caucaso australiore in alpinis elatioribus (? BM)

Synonymy: R. caucasicum Pallas var. stramineum W. Hooker, Bot. Mag. 62: t.3422 (1835). Type: a plant or the plate drawn from it (cited above), grown in Glasgow and flowering in iv 1835

Flags

Occurs in Countries: RU, TR Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: green, pink, yellow

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):312

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Rhododendron cavaleriei Leveille

Shrub to 5 m high, young branches glabrous. Leaves glabrous; blade narrowly obovate to oblanceolate, 75-150 x 35-40mm, base and apex attenuated, thinly coriaceous; petiole 8-12 mm long. Inflorescence buds lateral, at the ends of leafy shoots, 3- or more-flowered; bud scales glabrous or with minute cilia on the margins, caducous; pedicels 25-30 mm long, laxly or densely pubescent. Calyx of 5 minute lobes, glabrous or ciliate. Corolla white to rose, tube 12-I5mm, lobes 20-24 x 10-12mm. Stamens 10, filaments hairy on lower part (? sometimes glabrous). Ovary cylindric, 7 mm high, pubescent; style glabrous. Capsule c.40-50 mm long.

Distribution: China (Guizhou, Guangxi).

Illustrations:

Notes

The inflorescences with several flowers and hairy pedicels recall R. henryi, but the hairs of the pedicels form a fine pubescence in contrast to the glandular patent hairs of R. henryi. Also the leaves are longer and narrower than those of R. henryi.

Nomenclature

Type: China, Guizhou, sous prefecture de Tou-chan, v 1899, Cavalerie 2633 (holo. E).

Flags

Occurs in Countries: CN Subgenus: Azaleastrum Habit: Non-Tree Fl. Colour: rose

Philipson, W.R. & Philipson, M.N. (1986) A Revision of Rhododendron III. Subgenera Azaleastrum, Mumeazalea, Candidastrum and Therorhodion. Notes from the Royal Botanic Garden Edinburgh 44(1):12

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Rhododendron celebicum (Blume) DC.

Shrub to 1.5m; roots sometimes swollen and tuber-like. Twigs rounded, 1.5–3mm in diameter, sub-densely sub-stellately scaly, older stems glabrescent, smooth, often red; internodes 1.5–6cm. Leaves 3–7 together in distinct but loose pseudowhorls. Blade 30–70 x 15–30mm, elliptic to narrowly ovate-elliptic; apex shortly acuminate, sub-acute or obtuse; margin entire, narrowly cartilaginous, flat when fresh, slightly and narrowly revolute when dry; base broadly tapering; glabrescent and slightly rugose above at maturity, sub-densely scaly beneath. Scales small, flat or impressed, marginal zone thin, pale, silvery, large, angled or sub-stellately lobed; centre small, brown. Mid-vein narrow and slightly impressed above, strong and prominent beneath; lateral veins 5–7 per side, sub-patently spreading, anastomosing, faintly impressed above, very slightly or not raised beneath, without clear reticulation. Petiole 4–12 x 1–1.5mm, flattened, red, shallowly grooved above, scaly. Flower buds to 15 x 6mm, ellipsoid, smooth, except for low protuberances at the apices of the bracts, minutely pale-brown scaly outside and along the bract margins. Bracts 5–12 x 4–7mm, ovate to obovate, minutely pale-brown scaly outside or glabrous; margin with brown, stellate scales. Bracteoles c.15 x 1–2mm, linear below, sub-spathulate, dilated and irregularly impressed distally, glabrous. Inflorescence 3–8-flowered, an open umbel, the flowers hanging vertically downwards. Pedicels 15–20 x c.1mm, slender, densely stellate-scaly and papillose, not properly hairy. Calyx 2.5–3mm in diameter, disc-shaped, oblique, shortly obtusely 5-lobed, densely scaly outside. Corolla 35–46 x 20–25mm, tubular, pink to red, without scent; tube 30–35 x 6–8 x 9–11mm, cylindrical, straight, often angular and strongly pouched at the base, laxly to very laxly scaly outside, glabrous inside; lobes 8–11 x 6–10mm, sub-circular, mostly not overlapping, half-spreading to almost horizontal. Stamens irregularly spread around the mouth of the flower, or exserted to 8mm; filaments pink, glabrous; anthers 2–2.5 x 1mm, dark, brown, pores up to ½ the length of the anthers. Disc green, promi­nent, glabrous. Ovary 5–6 x 2mm, sub-cylindrical, pink, very densely silvery stellately scaly, tapering gradually distally; style glabrous or scaly at the base, as long as the corolla; stigma thick-globose. Fruit 25–38 x 35mm, fusiform-cylindrical, scaly. Seeds 7–8mm, without tails c.1mm, the longest tail to 4.5mm, the tails strongly crimped.

Habitat: Epiphytic in mossy forest

Distribution: Indonesia, Sulawesi, Minahasa: Mt Klabat, Lake Poso area, Mt Rantemario, Mt Gambuta.

Altitude: 1800-2600m

Notes

Named after the island on which it was found, Celebes (now Sulawesi).

Nomenclature

Type: Reinwardt s.n., 1821. Celebes, Menado: Mt Klabat, top, 1800–2000m (L, P).

Flags

Occurs in Countries: ID Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Vireya Habit: Epiphyte, Non-Tree Fl. Colour: pink, red

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:287

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Rhododendron cephalanthum Franchet

Variably sized, often contorted and sometimes prostrate shrub, 0-1-1.2 m, often with very thick lower stem. Leaf-bud scales persistent and very conspicuous. Leaves broadly elliptic to suborbicular, 15-47 x 7-23 mm, base usually rounded, apex obtuse or rounded, rarely emarginate, upper surface dark, glossy green, usually elepidote, lower surface fawn to brown, rarely dark brown or rusty with dense, overlapping scales in 2-3 tiers, those of the lower tier golden, paler than those of the upper tiers. Inflorescence dense, many-flowered; pedicels short, lepidote. Calyx lobes oblong, (3-)4-7 mm, lepidote or elepidote outside, margins usually ciliate with loriform cilia (rarely margined with scales), inner surface glabrous or slightly puberulent. Corolla white or pink, rarely yellowish, tube 6-5-14 mm, lobes (3-)4-8 mm, tube elepidote and glabrous outside, lobes often bearing a few scales on their backs, mouth of the tube densely pilose inside. Stamens 5(-7). Ovary lepidote. Capsule scarcely exceeding the calyx

Notes

Two subspecies, differing mainly in size, can be recognised

Flags

Occurs in Countries: CN, IN, MM Altitude Ranges: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: pink, yellow

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):161

Rhododendron cephalanthum subsp. cephalanthum

Habitat: Open meadows, moorland, rocky slopes

Distribution: India (Arunachal Pradesh), N Burma, China (N, NW & C Yunnan, S & SE Xizang)

Altitude: 3050-4500m

Illustrations:

  • Gard. Chron. 91:133 (1932)
  • Cox, Dwarf Rhododendrons 76 (1973)
  • Ic. Corm. Sin. 3: t. 4101 (1974)
Nomenclature

Type: China, Yunnan, in cacumine montis Koua-la-po prope Hokin, 26 v 1884, Delavay 59 (holo. P—n.v., iso. E)

Synonymy: R. chamaetortum Balfour f. & Kingdon Ward, Notes R.B.G. Edinb. 9:218 (1916). Type: China, Tibeto-Yunnan frontier, Ka-gwr-pu (Ka kar po) glacier valley, 15000 ft, vi 1913, Kingdon Ward 431 (holo. E). R. crebreflorum Hutchinson & Kingdon Ward, Notes R.B.G. Edinb. 16:173 (1931). Type: Assam, Delei valley, 13000 ft, Kingdon Ward 8337 (holo. BM, iso. E). R. nmaiense Hutchinson & Kingdon Ward, op. cit.: 252. Type: E Upper Burma, ridge of Naung chaung, Nwai Divide, 12-13000 ft, 16 vii 1914, Kingdon Ward 1791 (holo. E). R. cephalanthum var. crebreflorum (Hutchinson & Kingdon Ward) Cowan & Davidian, Rhodo. Yearbook 2:70 (1947). R. cephalanthum var. nmaiense (Hutchinson & Kingdon Ward) Cowan & Davidian, op. cit.: 71.

Rhododendron cephalanthum subsp. platyphyllum (Franchet ex Balfour f. & W. W. Smith) Cullen

Habitat: Cliffs and ledges

Distribution: NE Burma, China (NW & C Yunnan)

Altitude: 3050-3350m

Notes

Subsp. platyphyllum is, essentially, a large-sized variant of subsp. cephalanthum, reasonably distinct both morphologically and geographically. Cytological observations on the two taxa would be interesting, but subsp. platyphyllum is not available in cultivation.

Nomenclature

Synonymy: R. cephalanthum var. platyphyllum [Franchet ex] Diels, Notes R.B.G. Edinb. 7:211 (1912) nomen nudum. Type: China, Yunnan, in cacumine montis Tsang chan supra Tali, 27 vi 1887, Delavay (holo. P—n.v., iso. E). R. platyphyllum [Franchet ex] Balfour f. & W. W. Smith, Notes R.B.G. Edinb. 9:259(1916)

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Rhododendron cerasinum Tagg

Shrub, 1.2-3.7m; young shoots glabrescent. Leaves narrowly obovate to elliptic, 4.5-7 x 1.8-4cm, 1.7-2.5 x as long as broad, apex rounded, apiculate, base rounded, upper and lower surfaces glabrous, lower cuticle shortly papillate with some red sessile hair-bases; petioles 0.7-1.5cm, with sparse, well-developed, rufous, dendroid hairs that extend up the midrib on the upper surface of the leaves. Inflorescence 4—7-flowered; rhachis up to 5mm; pedicels 15-25mm, sparsely glandular. Calyx c.1.5mm, shortly stipitate-glandular, at least on the lobe margins. Corolla campanulate, crimson to scarlet or white with a deep pink border, nectar pouches darker, 35-45mm. Ovary shortly stipitate-glandular; style glandular to tip. Capsule c.20mm.

Habitat: Coniferous forests

Distribution: NE Upper Burma, China (SE Xizang)

Altitude: 3200-3800m

Illustrations:

Nomenclature

Type: N Burma, Seingku Wang, vi 1936, Kingdon-Ward6923 (holo. K; iso. E).

Flags

Occurs in Countries: CN, MM Altitude Ranges: 3,000 - 4,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: crimson, pink, scarlet, white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):418

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Rhododendron cernuum Sleumer

Shrub to 1m. Twigs spreading, tips reddish-brown-scaly; internodes 1.5–8cm. Leaves 4 together in pseudo­whorls. Blade 40–90 x 10–17mm, narrowly elliptic; apex shortly, to long acuminate; margin slightly revolute when dry; base tapering, glabrescent above with age, the remaining scales flat and not impressed, densely and persistently scaly beneath. Scales flat, with many touching or slightly crenate overlapping, forming a continuous layer, the marginal zone wide in relation to the small darker centre, deeply and irregularly to moderately lobed; centres impressed. Mid-vein impressed above, thick and prominent beneath; lateral veins 6–8 per side, straight and spreading, sometimes minutely depressed above, obscure beneath. Petiole 6–15 x c.1.5mm, semi-rounded, scaly. Outer bracts to 8 x 5mm, ovate to sub-spherical, abruptly subulate-tapering at the apex, densely scaly outside; inner ones ovate to sub-spathulate, obtuse. Bracteoles to 6mm, filiform, laxly scaly. Inflorescence c.5-flowered, an open umbel, the flowers half-hanging. Pedicels 10–15mm, slender, densely scaly. Calyx c.2.5mm in diameter, sub-oblique, almost cup-shaped, the margin spreading or reflexed, irregularly, shortly and obtusely 5-lobed. Corolla 10–12mm, broadly campanulate, yellow; tube c.8 x 2–3 x c.10mm, sub-densely scaly outside; lobes 5–6 x 4–5mm, broadly obovate, shortly retuse or irregularly crenate distally, scaly outside except near the margins. Stamens nearly as long as the corolla; filaments linear, long patently hairy in the proximal 1⁄3, glabrous distally; anthers 1.7mm. Disc prominent, very shortly hairy at the upper margin, glabrous below. Ovary c.2.5 x 1.7mm, ovoid-conical, densely patently hairy and scaly, abruptly contracted distally; style 4–5mm, scaly at the extreme base, glabrous distally; stigma large, 5-lobed.

Habitat: Reported growing on a dry sulphur-stone slope

Distribution: Indonesia, S Sumatra, near Bengkulu (Benkulen): Mt Kaba (Mt Belirang). Mt Belirang does not appear on modern maps. Bele­rang is the Indonesian for sulphur, and the local people harvest sulphur on Mt Kaba and often call it Mt Belerang. It seems most likely that Belirang and Kaba are one and the same place.

Altitude: Around 1500m

Notes

Latin – cernuus – slightly drooping, presumably alluding to the habit of the flowers.

Apparently known from only two specimens, not recently recollected or ever cultivated.

Nomenclature

Type: Rappard 63, 12 Aug. 1963. Sumatra, Benkulen, Mt Belirang (BO, L).

Flags

Altitude Ranges: 1,000 - 2,000m Subgenus: Vireya Habit: Non-Tree Fl. Colour: yellow

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:130

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Rhododendron chamaethomsonii (Tagg & Forrest) Cowan & Davidian

Dwarf shrub, 0.1 -lm; young shoots stipitate-glandular or sparsely tomentose, perulae ± deciduous or persistent. Leaves broadly obovate to elliptic, (2-)4-6 x (1.3-)1.8-3.2cm, 1.5-2.1 x as long as broad, apex rounded or retuse, base rounded to broadly cuneate, shortly decurrent, upper surface glabrous, lower surface glabrous or with a sparse whitish adpressed indumentum, epapillate; petioles 0.5-lcm, tomentose and/or stipitate-glandular. Inflorescence (1 -)2-5-flowered; rhachis c.5mm; pedicels 10-20mm, sparsely stipitate-glandular, sometimes also villous-tomentose. Calyx l-7(— 15)mm, minute or with well-developed, sometimes coloured, glandular-ciliate lobes. Corolla fleshy, campanulate, pink to deep crimson, usually unmarked, 25—45mm. Ovary densely to very sparsely rufous-tomentose with varying proportions of stipitate glands. Capsule c. 15 x 4mm.

Habitat: Amongst boulders, damp rocky slopes

Altitude: 4000-4600m

Notes

Closely allied to and apparently hybridising with R. forrestii (q.v.).

Flags

Occurs in Countries: CN Altitude Ranges: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: crimson, pink

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):406

Rhododendron chamaethomsonii var. chamaedoron (Tagg & Forrest) Chamberlain

Corolla carmine to crimson; calyx lobes to 7(- 15)mm; ovary sparsely hairy, sometimes glandular. Leaves with a thin discontinuous indumentum when mature; petioles and young shoots eglandular.

Nomenclature

Synonymy: R. repens Balfour f. & Forrest var. chamaedoron Tagg & Forrest, Notes R.B.G. Edinb. 16: 206 (1931). Type: China, SE Xizang, Tsarong, Salween/Kiu-chiang divide, W of Chamatong, 14500ft, vi 1922, Forrest 21768 (holo. E). china (SE Xizang & adjacent NW Yunnan).

Rhododendron chamaethomsonii var. chamaethauma

Corolla pale to deep pink; calyx minute, 1mm or less; ovary densely hairy.

Nomenclature

Synonymy: R. repens Balfour f. & Forrest var. chamaethauma Tagg, Notes R.B.G. Edinb. 16: 206 (1931). Type: China, SE Xizang, Doshong La, 12-13000ft, vi 1924, Kingdon-Ward 5847 (E, K). china (S Xizang, Doshong La & Deyang La).

Rhododendron chamaethomsonii var. chamaethomsonii

Corolla carmine to crimson; calyx lobes to 7(- 15)mm; ovary sparsely hairy, sometimes glandular. Leaves glabrous; petioles and young shoots glandular.

Distribution: China (SE Xizang & adjacent NW Yunnan)

Nomenclature

Synonymy: R. repens Balfour f. & Forrest var. chamaethomsonii Tagg & Forrest, Notes R.B.G. Edinb. 16: 206 (1931). Type: China, SE Xizang, Tsarong, Salween/Kiu-chiang divide, NW of Si-chi-to, 14-15000ft, vi 1922, Forrest 21723 (holo. E).

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Rhododendron championae Hooker f.

Shrub or small tree to 8 m high, young branches densely covered with glandular bristly hairs. Leafblade elliptic or obovate 70-150 x 25-50 mm, base cuneate, apex acuminate, chartaceous, upper surface sparsely short setose, increasing towards the margin, lower surface loosely bristly, especially on the mid-rib and principal veins, often also pubescent, margin ciliate; petiole c. 10-12 mm, with dense spreading bristles. Inflorescence buds lateral, clustered at the ends of leafy shoots, about 5-flowercd; bud scales viscid; pedicels c. 18-20 mm long, densely covered in coarse spreading glandular hairs. Calyx of 5 variable lobes, up to 12 mm long, narrow, densely ciliate. Corolla at first pink becoming white with yellow markings on upper lobe, glabrous, tube c. 12-15 mm, lobes c.40-45 x 25-30 mm. Stamens 10, filaments hairy on the lower part, Ovary cylindric, c.7mm long, densely bristly; style glabrous. Capsule narrowly cylindric, coarsely setose, c.35-40 mm long.

Distribution: China (Guangxi, Guangdong, Fujian, Zhejang, Hunan, Jiangxi), Hongkong.

Notes

The leaf margins of a number of species of section Choniastrum bear ciliate hairs in juvenile (or sucker) plants, but R. championae is the only species in which the adult leaf has marginal cilia. R. championae var. ovalifolium Tam (Survey Genus Rhododendron S. China 112, 1981) has bullate leaves, white flowers and some basal puberulence on the style.

Flags

Occurs in Countries: CN Subgenus: Azaleastrum Habit: Tree Fl. Colour: pink, white, yellow

Philipson, W.R. & Philipson, M.N. (1986) A Revision of Rhododendron III. Subgenera Azaleastrum, Mumeazalea, Candidastrum and Therorhodion. Notes from the Royal Botanic Garden Edinburgh 44(1):9

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Rhododendron charitopes Balfour f. & Fairer

Shrub to 1 -5 m. Leaves elliptic to obovate, cuneate at the base, apex very bluntly rounded to almost retuse, 30-55 x (14—)18—30 mm, upper surface dark green, elepidote or very sparsely lepidote, lower surface with very marked veins, and scales of varying density. Inflorescence (3-)4-5-flowered, pedicels lepidote, (18-)20-27 mm, rachis very short, pubescent with at least some loriform hairs which, in some specimens, tend to be dendritic. Calyx lobes ovate, rounded at the apex, (3-)5-7(-9) mm, somewhat glaucous, tepidote at the base and around the margins. Corolla campanulate, (15-)20-25 mm, tube (8-)9-12 mm, pink to purplish, sometimes spotted, elepidote or very sparsely lepidote outside. Capsule ovoid, c. 10 mm.

Notes

A variable species, which can be divided into two intergrading subspecies

Flags

Occurs in Countries: CN, MM Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: pink

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):141

Rhododendron charitopes subsp. charitopes

Habitat: On cliffs, among boulders and on rocky slopes, rarely in scrub

Distribution: NE Burma, China (NW Yunnan)

Altitude: 3200-4250m

Illustrations:

  • Bot. Mag. 157: t. 9358 (1934)
  • Ic. Corm. Sin. 3: t. 4005 (1974)
Notes

A natural hybrid between subsp. charitopes and R. campylogynum (p. 145) has been collected by Farrer (NE Burma, Chawchi pass, 3350 m, 16 vii 1920, Farrer 1726)

Nomenclature

Type: NE Burma, Shing Hong pass, 10500-12000 ft, 18 vi 1920, Farrer 1627 (holo. E)

Rhododendron charitopes subsp. tsangpoense (Kingdon Ward) Cullen

Habitat: Slopes, rocks, open mountainsides

Distribution: China (S Xizang)

Altitude: 2450-4100m

Notes

Subsp. tsangpoense is a northern vicariad of subsp. charitopes; though they do not overlap geographically, they approach very closely, and there is no very clear morphological separation between them. The name curvistylum has been applied to a plant collected at the locus classicus of tsangpoense, which is in no way different from the type of the latter. However, material cultivated as R. tsangpoense var. curvistylum (often as Kingdon Ward 5843) is different—it is a plant with very small, narrowly elliptic, acute leaves, and is probably a hybrid between subsp. tsangpoense and R. campylogynum.

Nomenclature

Synonymy: R. tsangpoense Kingdon Ward, Gard. Chron. 86:504 (1929). Type: China, SE Tibet, Doshong La, 12-13000 ft, 24 vi 1924, Kingdon Ward 5844 (holo. BM, iso. E). R. curvistylum Kingdon Ward, Plant Hunting on the Edge of the World 375 (1930) nomen nudum. R. tsangpoense var. curvistylum [Kingdon Ward ex] Cowan & Davidian, Rhodo. Yearbook 3:90 (1948). Type: China, SE Tibet, Doshong La, Kingdon Ward 5843 (holo. BM, iso. E)

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Rhododendron chevalieri Dop

Shrub to 2m. Twigs 2–2.5mm in diameter, smooth, rounded and at first densely brown scaly; internodes 3–5mm. Leaves in moderately tight pseudowhorls, 4–5 together, apparently rigidly held semi-erect. Blade 40–50 x 13–24mm, elliptic to narrowly obovate, very shortly acuminate to a broadly acute or obtuse apex; margin entire, flat to slightly revolute distally distinctly revolute in the proximal 1⁄3, especially when dry; base tapering and decurrent, glabrescent above, densely scaly beneath. Scales rounded, with a moderately large centre but broad, paler flange, lightly impressed. Mid-vein narrowly impressed above in the proximal ½–2⁄3, then flat; narrowly raised beneath throughout its length, sometimes terminating in an indistinct terminal gland. Petiole 4–10 x c.2mm, weakly grooved above, densely brown-scaly, often flushed pink. Bracts to 20 x 8mm, ovate, acute, with a few brown scales outside distally and along the margins, glabrous inside. Bracteoles 6 x 1mm, narrowly triangular, with a few teeth on the margin, glabrous. Inflorescence 1–4-flowered, the flowers held semi-erect. Pedicels 8–10 x 1–1.5mm, densely scaly, without simple hairs. Corolla 20–23 x 35–49mm, bright to pale yellow, without scent; tube 6–12 x 4–5 x 10–12mm, glabrous outside; lobes 15 x 12mm, half-spreading. Stamens spreading round the mouth of the flower, exserted to 7mm; filaments glabrous or with a few hairs at the base; anthers c.4 x 2mm. Disc glabrous. Ovary 5 x 25mm, with patent white hairs and brown scales; style 6 x 1mm, glabrous, bent to the lower side of the tube. Fruit 15–18 x 5–6mm, erect, prominently hairy and scaly.

Habitat: Evergreen forest domin­ated by Fokienia and Phyllostachys.

Distribution: Vietnam, (S) Prov. Khanh Hoa (Nhatrang) massif de Hon-ba; Lam Dong, Lac Duong, Bi Doup peak area.

Altitude: 1000-2100m

Notes

Named after the collector, Auguste Chevalier, who made many important collections in what is now Vietnam and Cambodia.

Nomenclature

Type: Chevalier 38709, 1 Sept. 1928. S. Annan, forêt vierge du Honba (P).

Flags

Altitude Ranges: 0 - 1,000m: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Vireya Habit: Non-Tree Fl. Colour: yellow

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:191

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Rhododendron chihsinianum Chun & Fang

Small tree, 4m; young shoots setulose-glandular, also with a loose tomentum. Leaves coriaceous, oblong, 19-23 x 5-7cm, 4-4.5 x as long as broad, apex rounded, base rounded to sub-cordate, margin with minute deciduous setulae below, lower surface with an evanescent pubescence; petioles 1.5-2cm, glandular-setulose. Inflorescence c. 8-flowered; rhachis c. 20mm; pedicels c. 10mm, brown-pilose, eglandular. Calyx c. 2mm, fimbriate. Corolla 7-lobed, broadly infundibular-campanulate, colour unknown, c. 40mm. Stamens c. 15. Ovary densely stipitate-glandular; style glandular to tip. Capsule not known.

Distribution: China (Guangxi)

Altitude: Around 850m

Notes

Allied by the original authors to R. strigillosum and R, monosematum but the 7-lobed corolla and glandular style suggest a closer affinity with R. auriculatum.

Nomenclature

Type: China, Guangxi, Lungsheng Hsien, Pingshui Hsiang, Hung Tan, Pichia Shin, 850m, 13 iv 1955, KwangfuExped. 56 (holo. Herb. Inst. Bot. Guangzhou)

Flags

Occurs in Countries: CN Altitude Ranges: 0 - 1,000m Subgenus: Hymenanthes Habit: Tree

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):241

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Rhododendron chionanthum Tagg & Forrest

Shrub, 0.6-lm; young shoots ± densely setose, eglandular. Leaves obovate, 6-7.5 x 2.2-2.8cm, c.2.5 x as long as broad, apex rounded, acuminate, base broadly cuneate, glabrous above when mature, with a discontinuous floccose tomentum beneath; petioles 0.5-lcm, setose. Inflorescence 4-6-flowered; rhachis c.5mm; pedicels 15-20mm, sparsely setulose-glandular. Calyx 2-3mm, lobes ciliate. Corolla tubular-campanulate, white, c.35mm. Ovary densely rufous-tomentose. Capsule not known.

Habitat: Rocky slopes

Distribution: ne Upper Burma, China (W Yunnan)

Altitude: Around 4400m

Notes

Allied to, or a hybrid of, R. haematodes subsp. chaetomallum but differing in the white flowers and discontinuous indumentum.

Nomenclature

Type: NE Upper Burma, western flank of the Salween/Kiu-chiang divide, 27°18'N, 98°40'E, 14000ft, vii 1924, Forrest25592 (holo. E).

Flags

Occurs in Countries: CN, MM Altitude Ranges: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):390

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Rhododendron christi Foerster

Small shrub to 1.2m. Twigs 1.5–2mm in diameter, rounded, laxly scaly, becoming glabrescent, smooth; internodes 4–11cm. Leaves 2–4 together in tight pseudo­whorls at the upper 2 or 3 nodes, sub-sessile. Blade 40–110 x 25–65mm, ovate; apex shortly or long-acuminate; margin entire, flat, slightly recurved when dry; base cord­ate to rounded; laxly scaly initially, glabrescent above, persistently scaly beneath. Scales flat, small, the thin marginal zone large, irregularly and deeply divided; centre darker, small, slightly impressed. Mid-vein narrow and deeply grooved above, strong and prominent beneath; lateral veins 4–6 per side, curved-ascending and joining, weakly or not impressed above, slightly prominent beneath; densely reticulate. Petiole 1–2 x 1–2mm, flattened, scaly. Flower buds to 20 x 12mm, ovate, smooth. Bracts to 20 x 8mm, outer ovate, the apex abruptly subulate or mucronate, very shortly appressed hairy outside and with a few scales distally in the central area; inner ones ovate, apiculate or obtuse, appressed-hairy in the upper part outside, margin minutely irregular and with fragile scales. Bracteoles to 20 x 5mm, linear below, spathulate towards the apex, laxly hairy, often with a few irregular teeth apically and with a few stalked scales on the margins. Inflorescence an open umbel of 2–5 flowers. Pedicels 15–25 x c.2mm, red, densely patently hairy, with few or no scales. Calyx 3–4mm in diameter, disc-shaped, densely hairy outside, with 5 short, obtuse ciliate lobes or occasionally longer up to 5mm. Corolla 30–45 x 25–35mm, tubular below, expanded and oblique at the lobes, bicoloured with a yellow tube and orange lobes, without scent; tube 20–25 x 6–7 x 12–18mm, yellow at the base or throughout, orange distally, densely long-hairy both inside and out, without scales; lobes 13–18 x 10–18mm, obovate-spathulate or sub-circular, hairy outside. Stamens exserted to 12mm, clustered on the upper side, unequal; filaments linear, densely patently hairy in the proximal ¼–1⁄3, glabrous distally; anthers 2–2.5mm, obovoid, apex truncate. Disc densely hairy in the upper ½. Ovary 5–7 x 2.5–3mm, cylindrical, continuous with the style, shortly hairy; style as long as the stamens, densely hairy to nearly the top; stigma oblique, rounded or weakly lobed. Fruit 30–35 x c.5mm, sub-cylindrical, widest in the upper 1⁄3, slightly curved, laxly hairy, valves thin, becoming twisted. Seeds 6–7mm, without tails 0.8mm, the longest tail 3.5mm.

Habitat: Mostly epiphytic in mossy forest and on grassland tree-ferns, or terrestrial in open forest or rock faces on cliffs

Distribution: Papua New Guinea, New Guinea (E), Mt Saruwaged and vicinity; Eastern, Western and Southern Highlands; Simbu District; Wharton Range; Finisterre Mts (Madang District). Indonesia, New Guinea (W), Wamena R.; Ibele valley.

Altitude: 1200-3000m

Notes

Named after Konrad H. Christ, Swiss fern specialist who was professor of botany at Basel.

The records from near Wamena are a surprising extension to the range of this species which had previously been known only from Papua New Guinea; some of these plants differ in having broadly tapering leaf bases but others are quite typical with cordate bases. Those with tapering leaf bases could be hybrids with R. curviflorum. It is reported hybridising with R. beyerinckianum (van Royen & Kores 1982), these hybrids having uniformly pink flowers (see R. x schoddei).

Nomenclature

Type: Keysser s.n., Oct. 1912. New Guinea (NE), Morobe District, Mt Saruwaged, Bolan, 2400–3000m (B†); ibid. Keysser 176 (BM, neotype).

Synonymy: R. christi var. loniceroides Schltr., Bot. Jahr. 1918. 55: 155. R. aff. wentianum Stonor, Rhod. Yearbook 1951. 6: 50, f.54. R. christii Foerster orth. var., Chamberlain et al., The Genus Rhododendron 1996. 17, 103.

Flags

Occurs in Countries: ID, PG Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Vireya Habit: Epiphyte, Non-Tree Fl. Colour: orange, yellow

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:301

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Rhododendron christianae Sleumer

Shrub to 3m. Twigs 2–3mm in diameter, rounded, sparsely scaly when young; internodes 2–12cm. Leaves 3–5 together in tight pseudowhorls. Blade 40–75 x 30–45mm, broadly elliptic or sub-obovate-elliptic, apex abruptly and shortly or gradually acuminate, obtuse, sometimes rounded or slightly emarginate, terminal gland thick, not protruding; margin flat; base broadly tapering or tapering; laxly scaly on both sides when young, glabrescent above, persistently laxly scaly beneath. Scales small, marginal zone variously lobed; centre slightly impressed. Mid-vein slightly or faintly impressed above, bluntly prominent in the proximal ½ beneath; lateral veins 5–7 per side, spreading, divided and curved-anastomosing before the margin, obscure above, a little raised beneath, reticulation inconspicuous. Petiole 5–10 x 1–1.5mm, grooved above, somewhat rugose, glabrous. Outer bracts to 15 x 8mm, ovate to obovate, innermost ones elliptic-spathulate, hairy on the outer middle line and at the apex, margin with fragile scales. Bracteoles c.15mm, linear-sub-spathulate to filiform, laxly hairy. Inflor­escence 2–5-flowered, an open umbel. Pedicels 10–27 x c.1mm, densely, shortly hairy, laxly scaly at both ends. Calyx c.4mm in diameter, oblique, disc-shaped, shortly obtusely 5-lobed, scaly and hairy outside. Corolla tubular, yellow shading to orange, especially at the lobes, and yellow or green on the tube; tube 25–35 x 7–10 x 15–20mm, straight, the base lobed, sparsely scaly outside, laxly hairy in the proximal 1⁄3 inside; lobes 15–25 x c.20mm, broadly obovate or sub-circular. Stamens unequal, regularly arranged around the flower, short ones at or a little beyond the mouth, longer ones exserted to c.12mm; filaments linear, yellow, densely and very shortly hairy in the proximal 1⁄3, glabrous distally; anthers 3–5 x c.1mm, blackish-purple, narrow-oblong, base with two short points. Disc slightly prominent, white-hairy on the upper margin. Ovary c.6 x 2.5mm, sub-cylindrical, abruptly contracted distally, white-hairy and scaly (scales hidden by the hairs); style 30–40mm, as long as the corolla tube, densely hairy and scaly proximally, becoming laxly so distally, glabrous for the 5–7mm below the stigma; stigma thick, 5-lobed. Fruit 30–34 x c.6mm, persistently appressed hairy, fusiform with longitudinal grooves.

Habitat: Compact terrestrial shrubs on precipitous rock faces or cliffs, overhanging deep gorges, in full sun. Locally abundant.

Distribution: Papua New Guinea, Milne Bay District, Daga country; Mt Simpson area, Mt Dayman area.

Altitude: 600-1525m

Notes

Named after Canon Cruttwell’s mother Christian Cruttwell, who went out to New Guinea to work as a missionary at the age of 55 and remained there for some 25 years.

‘When in flower (probably about June), it is a mass of orange and a conspicuous sight for miles, even from an aeroplane’ (Cruttwell 1971).

Nomenclature

Type: Cruttwell 410, 8 May 1954. New Guinea (SE), Milne Bay District, Kanasura, c.775m (E, K, L).

Flags

Occurs in Countries: PG Altitude Ranges: 0 - 1,000m: 1,000 - 2,000m Subgenus: Vireya Habit: Non-Tree Fl. Colour: green, orange, yellow

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:306

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Rhododendron chrysocalyx Levi. & Van.

Deciduous or semi-evergreen shrub, to 2m; densely branched, branchlets with dense coarse flat, yellowish-brown, adpressed hairs. Leaves persistent coriaceous, dimorphic, lanceolate to oblanceolate; spring leaves 1.5-6 x 0.5-1.5cm, apex acute, base cuneate, margin slightly crenulate, upper surface lustrous, glabrous except for a few coarse flat adpressed hairs on the midrib, net-veins conspicuously impressed, lower surface with few and similar hairs; summer leaves 5-10 x 3-5mm, otherwise as for spring leaves; petioles 3-5mm, covered with adpressed flat yellowish-brown hairs. Inflorescence (3-)6-12~flowered; pedicels 10-15mm, densely hairy. Calyx minute, hairy. Corolla tubular-campanulate, rose, 20-30mm, glabrous; tube 7-15mm, 3mm wide at base. Stamens 5, longer than corolla, papillate below middle. Ovary densely hairy, hairs coarse, lustrous, yellowish-red, adpressed; style glabrous. Capsule ovoid, densely hairy.

Habitat: Thickets

Distribution: China (Guizhou, N Guangxi, W Hubei, SE Sichuan)

Altitude: Around 700mm

Nomenclature

Type: Kouy-Tcheou (Guizhou), route de Mou-you-se a Tchen-Lin, vi 1904, Cava-lerie 2059 (E); Pin-Fa bord des ruisseaux, 25 iv 1904, Cavalerie 1796 (E).

Synonymy: R. spinigerum Levi, Bull. Acad. Geog. Bot. 24: 251 (1914). Type: Kouy-Tcheou (Guizhou), Hot a Pia Quay-Ho, 700m, 2 v 1912, Esquirol 3560 (holo. E). R. kouytchense Levi., Fl. Kouy-Tcheou 152 (1914), nom. nud., pro syn. sub. R. chrysocalyx. R. xiushanense Fang in Acta Phytotax. Sin. 21: 461 (1983). Type: China, Sichuan, Xiushan, Baigeqiao, 370m, 17 v 1978, S.X. Tan 354 (holo. SZ).

Flags

Occurs in Countries: CN Altitude Ranges: 0 - 1,000m Subgenus: Tsutsusi Habit: Non-Tree Fl. Colour: rose

Chamberlain, D.F. & Rae, S.J. (1990) A Revision of Rhododendron IV Subgenus Tsutsusi. Edinburgh Journal of Botany 47(2):107

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Rhododendron chrysodoron [Tagg ex] Hutchinson

Shrub, perhaps epiphytic, attaining 1 m or more in cultivation. Young shoots bristly with deciduous loriform setae. Leaves oblong-elliptic, up to 88 X 45 mm, obtuse at the apex, rounded at the base, loriform-ciliate when young, the lower surface papillose with close, golden yellow scales slightly sunk in pits. Inflorescence 3-4-fIowered, pedicels very short, densely lepidote. Calyx obscurely lobed, lobes 2-3 mm, lepidote, loriform-ciliate. Corolla campanulate, yellow, 29-30 mm, tube c. 15 mm, lepidote and pubescent at the base of the tube outside, pilose within the tube. Ovary lepidote. Capsule unknown.

Habitat: Scrub, 2450 m

Distribution: ne Burma (Adung valley)

Illustrations:

Notes

This species, which is known from only two wild-collected specimens and material in cultivation, is peculiar in several respects. It was described from cultivation and said to be raised from seed of Forrest 25446—a flowering specimen from Yungchang in Yunnan belonging to subsection Maddenia, and here identified as R. yungchangense (p. 53). The cultivated material is certainly not yungchangense, but appears to combine most of the characteristics of subsection Boothia with a few of subsection Maddenia, particularly scale type, calyx form, the large size of the flower and the presence of indumentum at the base of the corolla tube outside. On the basis of this evidence the plant might well have been regarded as a natural hybrid between yungchangense and sulfureum. However, in the same year that the plant first flowered in cultivation (1931), Kingdon Ward collected a specimen in the Adung valley on the Burmese/Chinese frontier, which matches it in every respect. The Adung valley is about 240 km north of Yungchang and was not visited by Forrest, so this does not explain the origin of the material in cultivation. It is possible that chrysodoron is distributed between the Adung valley and Yungchang, or that it is the result of occasional hybridisation between members of subsections Maddenia and Boothia, thus explaining the scattered distribution as we know it today. The description above has been drawn up from wild material; in cultivation the flowers may be larger (up to 40 mm) and, apparently, of a deeper yellow.

Nomenclature

Type: a cultivated specimen, said to derive from Forrest 25446—see below {holo. K, iso. E)

Synonymy: R. butyricum Kingdon Ward, nomen nudum.

Flags

Occurs in Countries: MM Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: yellow

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):135

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Rhododendron chunii Fang

Small shrub, to 2m; young shoots covered with adpressed flattened strigose red-brown hairs. Leaves monomorphic, coriaceous, persistent, elliptic to oblong-ovate, 1-2 x 0.5-0.9cm, 2 x as long as broad, apex acuminate, base broadly cuneate, margin entire, upper surface strigose, lower surface paler, strigose, especially on midrib; petiole 2-3mm, strigose. Inflorescence 2-3-flowered; pedicels 5-7mm, densely brown-strigose. Calyx strigose; lobes l-2mm, oblanceolate. Corolla funnel-shaped, lilac-purple, upper lobes flecked, 9-10mm; tube c.6 x 3mm, with 5 rows of glands on outer surface, also glandular within. Stamens 5, sub-equal, filaments minutely hairy below. Ovary densely covered in fine brown hairs; style covered with fuscous setose hairs and glands in lower half. Ripe capsule not known.

Habitat: Wooded slopes and ravines

Distribution: China (N Guangdong)

Notes

Tan describes the leaves as being dimorphic, the spring leaves 38-40 x 10-15mm; specimens seen by us do not confirm this.

Nomenclature

Type: China, Guangdong, Kock-Kiang (Qujiang), Chut-Hsin Tun, 18 iv 1930, X.P. Gao (S.P. Ko) 50411 (holo. SYS; iso. E, PE)

Flags

Occurs in Countries: CN Subgenus: Tsutsusi Habit: Non-Tree Fl. Colour: lilac

Chamberlain, D.F. & Rae, S.J. (1990) A Revision of Rhododendron IV Subgenus Tsutsusi. Edinburgh Journal of Botany 47(2):133

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Rhododendron ciliatum Hooker

Shrub to 2 m. Young growth loriform-setose, the older branches with the bases of the setae remaining. Leaves elliptic to narrowly elliptic, dark green and somewhat rugose above, paler green or brownish beneath, acute or obtuse at the apex, (44-)55-70(-90) x (21-)24-34 mm, the upper surface loriform-setose to some extent, particularly along the lower part of the midrib, the lower surface with scattered, rather unequal scales. Inflorescence 2-5-flowered, pedicels lepidote and rather densely loriform-setose. Calyx conspicuous, somewhat unequally 5-lobed, the lobes usually herbaceous, oblong-ovate, obtuse, lepidote near the base, loriform-ciliate, the largest 6-9 mm. Corolla white or white flushed pink, campanulate to funnel-campanulate, (32-)36-45 mm, the tube (19-)21-29 mm, glabrous and elepidote outside. Stamens 10, filaments pubescent towards the base. Ovary lepidote, style impressed, glabrous and elepidote. Capsule oblong-globose, c. 10-16 mm, lepidote.

Habitat: Hillsides, rocky places, forests

Distribution: Nepal, India (Sikkim), Bhutan, China (S Xizang)

Altitude: 2400-4000m

Illustrations:

Nomenclature

Type: Sikkim Himalaya, Lachen and Lachung valleys, 9000-10000 ft, Hooker (holo. K)

Flags

Occurs in Countries: BT, CN, IN, NP Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: pink, white

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):41

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Rhododendron ciliicalyx Franchet

Free-growing shrub. Young growth loriform-setose, the setae usually persistent. Leaves elliptic or narrowly elliptic, tapering to the base, acute at the apex, 70-110 x 26-40 mm, brownish beneath with rather dense but not contiguous scales. Inflorescence (2-)3-5-flowered. Calyx small, undulately lobed, persistently loriform-ciliate. Corolla white or pink, 50-60 mm, tube 25-34 mm, the tube pubescent but not lepidote outside, the lobes sparsely lepidote. Capsule ovoid-cyhndric, c. 20 mm

Habitat: Hillsides

Distribution: China (N & C Yunnan)

Altitude: Around 2400m

Illustrations:

Notes

R. ciliicalyx is a reasonably uniform species. R. missionarum is in no way different and probably comes from the same general area (the localities given by Maire have not been precisely identified). R. pseudociliicalyx was described from a cultivated specimen; it is also identical to R. ciliicalyx and is likely to have originated in Yunnan rather than Sichuan as surmised by Hutchinson (loc. cit.)

Nomenclature

Type: China, Yunnan, prope Mo-so-yn, 2400 m, Delavay 736 (holo. P—n.v., iso. E)

Synonymy: R. missionarum Leveille, Bull. Geogr. Bot. 24:20 (1915). Type: China, Yunnan, Tong-koua-pur, 3000 m, 1911, Maire (holo. E). R. pseudociliicalyx Hutchinson, Notes R.B.G. Edinb. 12:54 (1919). Type: a cultivated specimen (holo. E)

Flags

Occurs in Countries: CN Altitude Ranges: 2,000 - 3,000m Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: pink

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):51

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Rhododendron ciliilobum Sleumer

Erect shrub. Twigs rounded, sub-densely covered with reddish sessile or sub-sessile scales, without simple hairs. Leaves in a loose pseudowhorl, or spirally arranged several together at the tips of the stems. Blade 12–20 x 5–10mm, obovate; apex very shortly retuse, rarely rounded; margin very shortly revolute proximally, otherwise flat; base tapering, laxly scaly above, glabrescent with age and becoming a little rough, sub-densely scaly beneath. Scales sub-circular, sessile, marginal zone narrow and thin, sub-entire, centre large, thick and distinctly impressed. Mid-vein slightly impressed above, obtusely raised beneath, disappearing distally; lateral veins obscure above, weakly or not visible beneath. Petiole 2–3mm, rounded, scaly. Bracts to 6 x 3mm, ovate to obovate-spathulate, apiculate, with silky hairs and scaly in the upper outer part, densely white-fringed along the margins. Bracteoles to 5mm, filiform, hairy at the apex. Inflorescence of solitary or paired flowers, hanging vertically. Pedicels 6–10mm, slender, densely to laxly scaly with shortly stalked scales, and sometimes laxly short-hairy. Calyx c.2mm in diameter, minute, wavy and spreading, or with the narrow margin reflexed, scaly and very shortly hairy outside, with very short and obtuse lobes. Corolla 20mm, tubular; tube c.18 x 3 x 5mm, laxly scaly outside, glabrous inside; lobes c.4 x 3–4mm, ovate to sub-circular, erect at first, later spreading, distinctly irregularly-denticulate and ciliate at the apex. Stamens as long as the corolla on opening, finally slightly exserted; filaments filiform, glabrous; anthers 1.3mm. Disc glabrous. Ovary c.2.5 x 1.5mm, sub-ovoid-cylindrical, very densely scaly, gradually tapering distally; style c.17mm, thick-filiform, glabrous; stigma club-shaped, irregularly lobed. Fruit c.13 x 3.5mm, obliquely sub-cylindrical, deeply 5-grooved.

Habitat: In heath vegetation or Leptospermum forest

Distribution: Indonesia, New Guinea (W), Wissel Lakes region; Mt Kobre near Manokwari.

Altitude: 1755-2000m

Notes

Latin – cilium – a hair-like outgrowth; lobus – a rounded flattened organ. Referring to the characteristic cilia on the margin of the corolla lobes.

A form without hairs at the calyx and corolla lobes is known from the Balim Valley at 1600m.

Nomenclature

Type: Eyma 4787, 29 March 1939. New Guinea (W), Wissel Lake Region, Enarotali-Kugapa, Egogitoagapa (L, BO).

Flags

Occurs in Countries: ID Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Vireya Habit: Non-Tree

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:61

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Rhododendron ciliipes Hutchinson

Shrub of 1-3-1-6 m. Young growth loriform-setose. Leaves narrowly ovate to elliptic, rounded at the base, ± acuminate towards the apex, 50-70 x 30-35 mm, upper surface dark brownish green, lower surface brownish with rather lax scales; petiole loriform-setose. Inflorescence 3-4-flowered, pedicels lepidote. Calyx rather conspicuous, undulately 5-lobed, the lobes broadly triangular, obtuse, loriform-ciliate, lepidote, c. 4 mm. Corolla white with a greenish blotch at the base, 55-60 mm, tube c. 30 mm, pilose near the base, laxly lepidote all over the outside. Ovary lepidote. Capsule unknown

Habitat: Cliffs and boulders,

Distribution: China. (N & NW Yunnan)

Altitude: Around 3000m

Notes

Another obscure species. The paratype cited by Hutchinson with the original description [Forrest 25484) is very different from the type, and is here placed in R. pseudociliipes (p. 50). R. ciliipes is very similar in foliage to R. roseatum, also from the Shweli/Salween Divide, but it has an impressed style.

Nomenclature

Type: China, Yunnan, Shweli/Salween Divide, v 1925, Forrest 26384 (hoio. E)

Flags

Occurs in Countries: CN Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: green

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):48

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Rhododendron cinchoniflorum Sleumer

Erect shrub. Twigs slender, rounded, tips scaly; internodes 2–11cm. Leaves 4–6 together in tight pseudo­whorls, not aromatic. Blade 30–60 x 30–40mm, ovate-elliptic or mostly elliptic; apex shortly obtusely acuminate, sometimes apiculate with a small gland; margin entire, slightly revolute; base sub-truncate, rounded or cordate, sub-densely scaly above but quickly glabrescent, densely and persistently scaly beneath. Scales nearly round, wavy at the margin, very distinctly impressed, the scale pits becoming blackish with age. Mid-vein impressed above, strongly prominent beneath; lateral veins 3–4 per side, very slightly impressed above in fully mature leaves, somewhat prominent in younger ones, mostly not easily visible, especially beneath, reticulation obscure. Petiole 1.5–3 x 1–1.5mm, scaly, grooved above. Bracts to 10 x 7mm; outer bracts ovate, acute; inner ones obovate, scaly above along the middle line. Bract­eoles c.6 x 1mm, linear. Pedicels 5–8mm, slender, densely reddish-brown scaly. Calyx c.2.5mm in diameter, disc-like, scaly outside, glabrous inside, the margin undulate and shortly 5-lobed, spreading or reflexed at flowering. Corolla 32 x 14mm, (dry), white, trumpet-shaped; tube 25–30 x 2.5–3 x 2.5–3mm, nearly straight, 5-pouched at the base, very densely scaly outside, glabrous inside; lobes 10–12 x 8–9mm, spreading horizontally, obovate-elliptic, sparsely scaly outside, glabrous inside. Stamens unequal, not or slightly exserted from the throat; filaments filiform, laxly hairy; anthers 2–2.5mm, broadly oblong. Disc low, densely white-hairy. Ovary c.4 x 2mm, cylindrical-conical, densely and exclusively scaly, abruptly narrowed to the style, slightly 5-ribbed; style c.23mm, scaly and shortly patently hairy in the proximal 1⁄3, gradually becoming glabrous distally; stigma shortly obconical, minutely crenulate.

Habitat: In open montane shrub­beries especially in disturbed areas at roadsides.

Distribution: Indonesia, New Guinea (W), Wissel Lakes, 2400m, and on the southern side of Mt Jaya (Carstensz).

Notes

Latin – Cinchona – a South American plant in the Rubiaceae from which was derived the antimalarial ‘quinine’; florum – pertaining to the flower. The flowers are reminiscent of those of the quinine plant.

Nomenclature

Type: Eyma 5264, 11–17 Oct. 1939. Papua, Wissel Lake Region, Look-out Perai, 2400m (BO, L).

Flags

Occurs in Countries: ID Subgenus: Vireya Habit: Non-Tree Fl. Colour: white

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:66

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Rhododendron cinerascens Sleumer

Shrub to 2m. Twigs rounded, slender, grey, tips laxly scaly; internodes 2.5–10cm. Leaves 4–6 together in pseudowhorls. Blade 40–55 x 12–23mm, elliptic to obovate; apex shortly obtusely acuminate, rarely rounded; margin entire, flat; base tapering; sub-densely scaly initially on both sides finally glabrescent above, persistently scaly beneath. Scales thin, flat, irregularly lobed; centre small, impressed. Mid-vein shallowly impressed above, prominent beneath, especially proximally; lateral veins 6–8 per side, inconspicuous. Petiole 6–10 x c.1.3mm, grooved above, flattened, scaly initially. Bracts to 15 x 7mm, ovate to obovate-spathulate, laxly scaly outside and with hairs apically, glabrous internally, ciliate and with scales at the margin. Bracteoles 10–15 x 1mm, filiform to sub-spathulate. Inflorescence 5–7-flowered. Pedicels 9–20 x 0.5mm, densely scaly, laxly and very shortly hairy. Calyx very oblique, a thin, wavy, irregularly 5-dentate rim, one or more teeth elongate to 2–4mm. Corolla 50–60mm, trumpet-shaped, white; tube 37–50 x c.2.5 x 3–3.5mm, cylindrical, straight or slightly curved, densely scaly, not hairy outside, laxly hairy inside in the proximal 1⁄3 only; lobes c.10 x 6–7mm, spreading, spathulate-obovate, laxly scaly outside, glabrous inside. Stamens well exserted from the corolla tube; filaments filiform, hairy in the proximal ½ only; anthers c.2.5mm, oblong, base obtuse. Disc shortly hairy at the upper margin. Ovary c.5 x 1.2mm, elongate-cylindrical, sub-densely scaly and sub-appressed-hairy, gradually narrowed distally; style exserted for c.10mm, scaly and sub-patently hairy for 30mm above the base, otherwise scaly only, nearly to the top; stigma shortly obconical-globose.

Habitat: Secondary forest amongst Sphagnum

Distribution: Indonesia, New Guinea (W), Wissel Lakes area. Two collections.

Altitude: Around 1750m

Notes

Latin – cinerascens – becoming ash-grey, alluding to the colour of the twigs.

An anomalous collection from the Vogelkop (van Royen & Sleumer 7836) keys out to this species but is from much lower altitude (700m). Never cultivated.

Nomenclature

Type: Eyma 4854, 11 April 1939. New Guinea (W), Wissel Lake region, Upper Ennaro Valley and Puraida ridge, 1755m (L, A, BO, K, SING).

Flags

Occurs in Countries: ID Altitude Ranges: 1,000 - 2,000m Subgenus: Vireya Habit: Non-Tree Fl. Colour: white

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:173

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Rhododendron cinnabarinum Hooker

Straggling shrub up to 7 m in favourable locations. Young growth lepidote and often glaucous or with a pruinose bloom. Leaves mostly evergreen, sometimes deciduous, broadly to narrowly elliptic, rounded to the ± obtuse apex, tapered to cordate at the base, 30-90 x 27-50 mm, lepidote or elepidote above, lepidote beneath with rather fleshy, narrowly rimmed equal or unequal scales. Inflorescences all terminal, 2-7-flowered, pedicels lepidote. Calyx disc-like or undulate, lepidote. Corolla tubular to campanulate, variable in colour: yellow, orange (sometimes with a purple flush), red, red and yellow, or purple; usually with a waxy, pruinose bloom, 25-36 mm, the tube 15-22 mm. Stamens 10, filaments pubescent towards the base, rarely entirely glabrous. Ovary lepidote and sometimes puberulous at the apex. Style glabrous or sparsely pubescent or rarely lepidote at the base. Capsule lepidote, cylindric, c. 10 mm.

Notes

A very variable species, divisible into three vicariating subspecies

Flags

Occurs in Countries: BT, CN, IN, MM, NP Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: orange, purple, red, yellow

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):123

Rhododendron cinnabarinum subsp. cinnabarinum

Corolla lobes elepidote outside; most leaves evergreen; corolla variable in colour, rarely purple. Leaves relatively narrow, length/breadth ratio 2.2 or more, usually elepidote above; corolla usually ± tubular-campanulate

Habitat: Hillsides, forest and forest margins

Distribution: Nepal, India (W Bengal, Sikkim), Bhutan, China (S Xizang)

Altitude: 2750-3950m

Illustrations:

  • The Garden 15: pl. 169 (1879)
  • The Garden 44: t. 940 (1893)
  • Millais, Rhododendrons, opp. p. 24 (1917)
  • Urquhart, The Rhododendron 2: t. 25 (1962)
  • Stainton, Forests of Nepal t. 109 (1972)
Notes

The corolla of subsp. cinnabarinum is usually somewhat tubular, and varies in colour from dull red, through coppery red to red and yellow or orange.

Nomenclature

Type: Sikkim Himalaya, Hooker (holo. K)

Synonymy: R. roylei Hooker, Rhodo. Sikkim Himalaya t. 7 (1849). Type: Sikkim Himalaya, Hooker (holo. K). R. blandfordiiflorum W. J. Hooker, Bot. Mag. 82: t. 4930 (1856). Type: Sikkim Himalaya, (J. D.) Hooker (holo. K). R. cinnabarinum var. roylei (Hooker) Hort. R. cinnabarinum var. blandfordiiflorum (Hooker) Hort.

Rhododendron cinnabarinum subsp. tamaense (Davidian) Culien

Corolla lobes lepidote outside; most leaves deciduous; corolla purple.

Habitat: Thickets and forest margins

Distribution: N Burma

Altitude: 2750-3200m

Notes

Geographically disjunct from the rest of R. cinnabarinum, but clearly sustaining the W-E trends in various characters shown by the other subspecies. Its corolla is campanulate and purple.

Nomenclature

Synonymy: R. tamaense Davidian, Rhododendrons (RHS) 1972:54-55 N Burma, N Triangle, Tama Bum, 10000-10500 ft, 20 vi 1953, Kingdon Ward 21021 (holo. BM)

Rhododendron cinnabarinum subsp. xanthocodon (Hutchinson) Culien

orolla lobes elepidote outside; most leaves evergreen; corolla variable in colour, rarely purple. Leaves relatively broader, length/breadth ratio less than 2.2, usually persistently lepidote above; corolla usually campanulate

Habitat: Hillsides, forests, forest margins

Distribution: India (Arunachal Pradesh), Bhutan, China (S Xizang)

Altitude: 3050-3950m

Illustrations:

  • Urquhart, The Rhododendron 1: t. 13 (1958)
  • Hara (ed.), Photo-album of Plants of E Himalaya t. 165 (1968)
  • Bot. Mag. 179: t. 634 (1972-3)
Notes

The corollas of subsp. xanthocodon are campanulate and vary in colour from clear yellow to apricot, yellow flushed with purple (either when young, when old, or permanently), or purple. The subspecies intergrades with subsp. cinnabarinum in Bhutan, where many intermediates occur.

Nomenclature

Synonymy: R. xanthocodon Hutchinson, Gard. Chron. 95:409 (1934). Type: a cultivated specimen derived from Kingdon Ward 6026 (holo. K). R. concatenans Hutchinson, ibid. 97:374 (1935). Type: a cultivated specimen derived from Kingdon Ward 5874 (holo. K, iso. E). R. cinnabarinum var. pallidum W. J. Hooker, Bot. Mag. 80: t. 4788 (1854). Type: a cultivated specimen (holo. K). R. cinnabarinum var. purpurellum Cowan, Notes R.B.G. Edinb. 21:147 (1951). Type: Tibet, Natrampa, Chayul Chu, 10000 ft, 27 iv 3936, Ludlow & Sherhff 1354 (holo. E, iso. BM)

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Rhododendron circinnatum Cowan & Kingdon-Ward

Leaves elliptic to oblong, up to 11 x 3.5cm, lower surface with a thin mid-brown crisped indumentum.

Notes

Differs from R. lanatum in its predominantly glandular ovary that only has a few lanate hairs.

The only specimen seen is very poor and only has old corollas; the flower colour is therefore not known. In the absence of adequate material, the status of this taxon is unclear.

Nomenclature

Type: China, S Xizang, Bimbi La, 13-14000ft, 12 vii 1935, Kingdon-Ward 11964 (iso. E).

Flags

Subgenus: Hymenanthes Habit: Non-Tree

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):370

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Rhododendron citriniflorum Balfour f. & Forrest

Dwarf shrub, 0.2-l(-1.5)m; young shoots glabrous or with a white ± floccose tomentum. Leaves obovate to elliptic, 4-6(-7.5) x 1.5—2.3cm, 2.2-2.7(-3.3) x as long as broad, apex rounded, apiculate, base ± cuneate, glabrous above when mature, with a dense thick grey-brown ramiform tomentum beneath; petioles 0.5-lcm, usually ± winged, glabrous or with a white floccose tomentum when mature. Inflorescence 2-6-flowered; rhachis 2-3mm; pedicels 10-20mm, stipitate-glandular or with a mixture of long-branched hairs and glands. Calyx 2-12mm, when well-developed ± cupular, lobes ciliate or glandular-ciliate, otherwise glabrous. Corolla not fleshy, tubular-campanulate, yellow or orange to carmine, 32-45mm. Ovary stipitate-glandular and/or densely rufous-tomentose. Capsule 8-12 x 4-6mm.

Habitat: Cliffs, rocks, moorland, occasionally in thickets

Distribution: China (SE Xizang, NW Yunnan)

Altitude: 4000-4600m

Notes

The two extremes, var. citriniflorum with yellow flowers, a short calyx and glandular ovary, and var. horaeum with red flowers, a well-developed calyx and a tomentose, eglandular ovary, are distinct. There is however a range of intermediates (var. horaeum as recognized here includes plants with flowers that are orange or tinged with red). The intermediates fall into two groups. The first, with yellowish-red flowers and glandular ovary, includes plants referred to R. citriniflorum subsp. rubens Cowan (Notes R.B.G. Edinb. 20: 14, 1940, type: Rock 23245, E) and the following: Forrest 21859; Rock 10109, 10111, 23669. The second group, with yellow flowers and an eglandular ovary, include: Forrest 25595; Rock 10106, 22189, 22277.

A number of plants are intermediate between, and apparently part of hybrid swarms involving R. catacosmum, R, citriniflorum and R. temenium: i.R, x xanthanthum Tagg & Forrest in Notes R.B.G. Edinb. 15:308 (1927). Type: China, SE Xizang, Tsarong, Salween/Kiu-chiang divide, NW of Si-chi-to, 14000ft, vi 1922, Forrest 21275 (holo. E). Shrub, 0.5-1.5m; young shoots densely setulose. Leaves obovate, 9-10 x c.4cm, 2.3-2.5 x as long as broad, lower surface with a loose, brown lanate, ± continuous tomentum. Calyx 10-15mm, cupular. Corolla creamy yellow flushed crimson, 47-60mm. ii. R. x hillieri Davidian, Rhododendrons with Magnolias and Camellias 47 (1974). Type: China, SE Xizang, Tsarong, Salween/Kiu-chiang divide, NW of Si-chi-to, 13-14000ft, vi 1922, Forrest 21736 (holo. E). Shrub, 0.3-1.8m; young shoots densely tomentose, sometimes also with a few setae. Leaves obovate, 4.5-7 x 2-3cm, 2-2.5 x as long as broad, indumentum arachnoid-floccose, sparse and discontinuous. Calyx 7-10mm, cupular. Corolla rose-pink to deep crimson, 30-50mm. iii. 1R. citriniflorum x R. temenium, Shrub, 0.6-1.3m; young shoots tomentose and often densely setulose. Leaves 5-8 x 2.3-3(-4)cm, indumentum greyish to fawn, tomentose, dense to continuous. Calyx c.7mm. Corolla 35-40mm, yellow flushed rose to crimson. The setose indumentum on the young shoots and petioles of some of these plants (assumed to be derived from R. temenium), is like that of R. haematodes subsp. chaetomallum, a taxon that might also be involved in this hybrid complex. At Si-chi-to there are plants referable to all three hybrids as well as to the three putative parents. It is perhaps significant however that subsp. chaetomallum does not occur there.

Flags

Occurs in Countries: CN Altitude Ranges: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: carmine, orange, yellow

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):392

Rhododendron citriniflorum var. citriniflorum

Corolla yellow; calyx 2-5(-10)mm; ovary and usually pedicels stipitate-glandular.

Notes

The following fruiting specimens with glandular capsules are probably referable to var. citriniflorum: Forrest 15294, 22680; Rock 10905, 119, 124.

Nomenclature

Type: China, W NW Yunnan, Mekong/Salween divide, 28°12'N, 13000ft, vii 1917, Forrest 14271 (holo. E; iso. K)

Synonymy: R. chlanidotum Balfour f. & Forrest, Notes R.B.G. Edinb. 13: 38 (1920). Type: China, SE Xizang, Tsarong, Ka-gwr-pu, 13-14000ft, vii 1918, Forrest 16714 (holo. E; iso. K).

Rhododendron citriniflorum var. horaeum (Balfour f. & Forrest) Chamberlain

Corolla yellowish-red to carmine; calyx (2—)7 —12mm; ovary and pedicels eglandular.

Notes

The following fruiting specimens are probably referable to var. horaeum: Forrest 14752, 22862, 25901, 25913; Rock9099, 11203, 11206.

Nomenclature

Synonymy: R. horaeum Balfour f. & Forrest, Notes R.B.G. Edinb. 13: 264 (1922). Type: China, SE Xizang, Tsarong, Salween/Kiu-chiang divide, ix 1921, Forrest 20287 (holo. E). R. citriniflorum Balfour f. & Forrest subsp. aureotum Cowan in Notes R.B.G. Edinb. 20: 75 (1940). Type: China, SE Xizang, Tsarong, on Ka-gwr-pu, 14000ft, vii 1917, Forrest 14503 (holo. E).

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Rhododendron citrinum (Hassk.) Hassk.

Notes

Latin – citrinus – lemon yellow, alluding to the colour of the flowers.

Nomenclature

Type: Hasskarl s.n. Indonesia, Java, Mt Gedeh Tjibureum, not preserved. Lectotype: Docters van Leeuwen 8245, the same locality (BO).

Synonymy: Azalea citrina Hassk., Flora 1842. 25(2): 30. R. zippelii Blume, Fl. Jav. Pl. inéd. 1863–83. t.4. R. jasminiflorum (non Hook.) Koord., Junghuhn Gedenkb. 1910. 184.

Flags

Occurs in Countries: ID Altitude Ranges: 0 - 1,000m: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Vireya Fl. Colour: orange, red, yellow

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:197

Rhododendron citrinum var. citrinum

Small, spreading shrub, to 2m. Twigs 1–2mm in diameter, rounded, densely covered with flat pale-brown scales at first, glabrescent with age; internodes 1–5cm. Leaves 4–5 together in pseudowhorls, very unequal. Blade 20–60 x 10–30mm, elliptic, broadly-elliptic, rarely obovate-elliptic; apex broadly acute, obtuse to rounded, sometimes with a very small terminal gland; margin narrowly revolute in dry specimens, flat when fresh; base tapering; densely to sparsely scaly, quickly glabrescent above, more persistently scaly beneath. Scales flat, small, variously obtusely angled or more deeply indented in the marginal area which often decays leaving the small, dark, slightly impressed centres. Mid-vein slightly impressed above, prominent beneath, often conspicuously purplish-red for most of its length; lateral veins 5–8 per side, widely spreading, anastomosing, faintly raised beneath, often inconspicuous. Petiole 5–12 x c.1mm, scaly, slender, distinctly grooved above when fresh. Flower buds ovoid, to 10 x 5mm, smooth, green with a strong reddish-purple flush, often with a few spreading to recurved bracts around the base. Outer bracts triangular to ovate-acuminate, with pale brown scales at the tips outside and also minutely and densely, shortly hairy; inner ones ovate to spathulate, minutely and densely shortly hairy outside, fringed along the margin with scales, these inner ones with a highly irregular margin. Bracteoles to 8mm, filiform, almost glabrous. Inflorescence 1–4-flowered, the flowers half-hanging to hanging vertically downwards, without scent or sometimes reported as a little fragrant. Pedicels 15–20mm, red, slender, shortly hairy and sparsely scaly below, more densely so distally. Calyx 3–4mm in diameter, oblique, disc-shaped, or shortly and obtusely 5-lobed sometimes with one lobe a little longer than the others, scaly outside. Corolla 15–19 x 10–14mm, campanulate, pale-yellow to yellowish-white, lobed nearly halfway; tube 10–12 x 4–5 x 8–9mm, laxly scaly to almost glabrous outside in the Javanese, but more densely scaly in the Balinese specimens; glabrous inside; lobes c.9 x 10mm, semi-erect, obovate-spathulate, apex rounded or very slightly retuse, overlapping to ¾. Stamens 5, loosely clustered on the lower side of the flower, the anthers exserted to c.5mm; filaments 12–15mm, linear, glabrous, pale yellow, red or orange; anthers 2.2–2.6 x c.1mm, oblong, deeply emarginate at both ends, yellow or orange. Disc prominent, glabrous. Ovary 3–4 x c.1.5mm, green, obliquely oblong-ellipsoid, somewhat 5-angled, papillose-scaly mostly at the base, occasionally all over, abruptly contracted distally; style 6–8mm, red or orange, glabrous, slightly expanded upwards; stigma rounded-sub-globose, on the lower side of the mouth. Fruit 15–27 x c.4mm, obliquely cylindrical, shortly tapering at both ends, slightly curved, red, deeply 5-grooved, glabrous, on opening the valves reflexing and often twisting, the placentae breaking away from the base and weakly spreading. Seeds 5.5–6mm, without tails c.1.2mm, the longest tail to 2.6mm, the tails crimped, sometimes strongly so.

Habitat: In very humid primary forest, sub-alpine forest or forest margins

Distribution: Indonesia, W Java, Mt Salak, Mt Gedeh, Mt Galunggung, Mt Patuha, Mt Gegerbintang, Mt Masigit, Mt Pangrango and Mt Mala­bar. Also reported for C Java and possibly growing on Mt Diëng but no specimens have been preserved. Bali, Mt Abang.

Altitude: 1000-2900m

Notes

Collected in Java by Mr Henshall for Rollisons Nursery and flowering in May 1854 from which material it was figured in Curtis’s Botanical Magazine (t.4797).

Rhododendron citrinum var. discoloratum Sleumer

Corolla mostly orange, bright red, rarely pale yellow. Ovary completely or almost entirely covered in scales.

Habitat: In mossy forest, on ridges

Distribution: Indonesia, Sumatra, Atjeh, West Coast, Palembang and Lampong.

Altitude: 1220-2500m

Notes

Latin – discolor – of another colour, alluding to the usually red or orange flowers of this variety.

The fact that pale yellow flowers are recorded from Sumatra makes this variety of doubtful significance as some Javan specimens have the ovaries entirely covered with scales.

Nomenclature

Type: Meijer 4871. Sumatra, Mt Sago near Pajakumbuh, summit region, 1800–2000m (L, BM, SING).

Synonymy: R. magniflorum Forbes, Wand. 1885. 208 nom. nud. R. citrinum (non Hassk. s.str.) Miq., Fl. Ind. Bat. 1860. Suppl. 1: 251, 586. R. multicolor (non Miq.) Moore, J. Bot. 1925. 63: 57.

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Rhododendron clementinae Forrest

Shrub, l-3m. Leaves ovate-lanceolate, (6.5-)9-14 x (3-)4.5-8cm, 1.5-2 x as long as broad, apex rounded, obtuse, base + cordate, lower surface with a thick whitish to buff bistrate indumentum, the upper layer ramiform, lanate-tomentose, the lower compacted; petioles 1.5—2cm, glabrous when mature. Inflorescence 10-15-flowered; rhachis up to 12mm; pedicels 15—30mm, glabrous, stout. Calyx c.lmm, glabrous, lobes rounded. Corolla 7-lobed, campanulate, white to deep rose, with purple flecks, 40-50mm. Ovary and style glabrous. Stamens 12-14. Capsule c.20 x 10mm.

Habitat: Open forests, among boulders

Distribution: China (NW Yunnan, SW Sichuan)

Altitude: 3350-3950m

Illustrations:

Notes

A distinctive species, the only one in subsection Taliensia with a consistently 7-lobed corolla. A specimen from S Xizang, Ludlow, Sherriff & Taylor 3868, is technically referable to R. clementinae on account of its 7-lobed corolla but it has an apiculate leaf with a thin white indumentum beneath and white-tomentose petioles. Without further material, the taxonomic significance of these differences remains uncertain but the locality is considerably further west of the present known range of the species.

Nomenclature

Type: China, Yunnan, on the mountains of the Chungtien Plateau, 11000ft, vii 1915, Forrest 10857 (holo. E; iso. K).

Flags

Occurs in Countries: CN Altitude Ranges: 3,000 - 4,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: purple, rose, white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):358

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Rhododendron codonanthum Balfour f. & Forrest

Dwarf shrub, 0.3-1.3m. Leaves oblanceolate to elliptic, 4-6.5 x 1-1.8cm, 3.5-4.5 x as long as broad, apex acute, base cuneate, lower surface with a sparse reddish sub-ramiform indumentum intermixed with stipitate glands, persistent on the midrib, detersile on the lamina; petioles c.0.5cm, tomentose. Inflorescence c.6-flowered; rhachis minute; pedicels 25-30mm, sparsely stipitate-glandular. Calyx 2-4mm, glandular-ciliate, lobes rounded. Corolla campanulate, bright yellow with crimson spots, c.30mm. Ovary stipitate-glandular; style glandular to tip. Capsule not known.

Habitat: Stony slopes

Distribution: China (NW Yunnan)

Altitude: 3650-4250m

Notes

A poorly known species, apparently without close allies

Nomenclature

Type: China, NW Yunnan, Mekong/Salween divide, E of Yeh-chih, 8 viii 1921, Forrest 19810 (holo. E)

Flags

Occurs in Countries: CN Altitude Ranges: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: crimson, yellow

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):337

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Rhododendron coelicum Balfour f. & Fairer

Small shrub; young shoots sparsely stipitate-glandular. Leaves obovate, 6-8.5 X 3.1-4.4cm, 1.6-2 x as long as broad, apex rounded, apiculate, base rounded, upper surface glabrous, lower surface with a thick fulvous dendroid tomentum; petioles 1 — 1.5cm, sparsely short stipitate-glandular. Inflorescence c. 10-flowered; rhachis c.5mm; pedicels 7-10mm, shortly stipitate-glandular, often also with remnants of the juvenile tomentum. Calyx 5-7mm, lobes rounded, glandular-ciliate, otherwise glabrous. Corolla fleshy, tubular-campanulate, crimson, 38—45mm. Ovary shortly stipitate-glandular and tomentose. Capsule 15-18 x c.5mm, curved.

Habitat: Shaded screes, cliffs

Distribution: NE Upper Burma and adjacent parts of China (W Yunnan)

Altitude: 2750-4400m

Illustrations:

Notes

Closely allied to R. pocophorum but differing in its broader leaves and non-tomentose petioles. One plant, Kingdon-Ward 13150, is intermediate between and may be a hybrid of R. coelicum and R. haematodes subsp. chaetomallum. It not only has the stipitate glands of the former but also the setae on the young shoots and petioles of the latter.

Nomenclature

Type: NE Upper Burma, Chawchi Pass, 11000ft, 15 x 1920, Farrer 1548 (holo. E; iso. K)

Flags

Occurs in Countries: CN, MM Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: crimson

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):389

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Rhododendron coeloneuron Diels

Tree, 4-8m. Leaves oblanceolate, 7.5-12 x 2.5-4cm, 3-3.5 x as long as broad, apex acuminate, sometimes with extreme tip blunt, base cuneate, lower surface with a dense bistrate indumentum, the upper layer rufous, ramiform-tomentose, persistent or evanescent, the lower whitish, adpressed, scurfy; petioles 1—2cm, densely rufous-tomentose. Inflorescence 6-9-flowered; rhachis c.3mm; pedicels 7- 15mm, densely rufous-tomentose. Calyx c.2mm, tomentose. Corolla funnel-campanulate, pink or purplish, 40-45mm. Ovary densely rufous-tomentose; style glabrous. Capsule not known.

Distribution: China (SE Sichuan)

Notes

Distantly allied to R. rufum and R. wiltonii

Nomenclature

Type: China, E Sichuan, Nan Chuan, Met'u-Wan, 1891, Bock von Rosthorn 929 (photo. E)

Flags

Occurs in Countries: CN Subgenus: Hymenanthes Habit: Tree Fl. Colour: pink

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):361

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Rhododendron coelorum Wernham

Prostrate shrub to 15cm. Twigs c.1mm in diameter, covered with stalked stellate scales, becoming glabrescent, laxly warty. Leaves spirally arranged, not aggregated into pseudowhorls. Blade 6–12 x 4–8mm, ovate or elliptic; apex broadly acute to obtuse, sometimes with a protruding gland; margin entire to sub-crenulate, cartilaginous, narrowly revolute; base broadly tapering to rounded; quickly glabrescent above, more persistently but laxly scaly beneath. Scales irregularly obtusely stellate-lobed, slightly or not impressed. Mid-vein impressed above and raised beneath, or almost smooth; lateral veins obscure. Petiole c.1–1.5 x 1mm, grooved above, scaly. Flower buds to 13 x 7mm, ovate, acute with the bract tips spreading out, almost glabrous. Bracts to 10 x 5mm, ovate, glabrous outside except for a few scales near the acute points outside. Flowers 1–2, horizontal to hanging. Pedicels 10–17 x 0.5mm, sub-densely stellate-scaly, with or without hairs. Calyx c.2.5mm in diameter, disc-shaped, obscurely 5-lobed. Corolla 25–30 x 14–18mm, pink to red, without scent; tube 20–25 x 4–5 x 10–12mm, tubular, slightly expanded upwards, very sparsely scaly outside, glabrous inside, oblique; lobes 5–7 x 5–7mm, sub-circular, half-spreading. Stamens unequal, exserted to c.3mm; filaments linear, glabrous; anthers sub-orbicular, c.1.5mm. Disc prominent, glabrous. Ovary sub-cylindrical, densely scaly, c.3–6 x 2mm, gradually tapering distally; style glabrous, nearly as long as the corolla; stigma obconical-­globose. Fruit 18–22 x c.2.5mm, fusiform.

Distribution: Indonesia, New Guinea (W), Mt Jaya (Carstensz), Lake Habbema

Altitude: 2600-3810m

Notes

Latin – caelestis – heavenly; no doubt an impressive plant.

Still a poorly known species but distinctive in its prostrate habit and spirally arranged leaves. Sleumer (1973) commented that it might have to be united with R. schizostigma and R. disterigmoides but both of these species have a much more vigorous erect habit.

Nomenclature

Type: Kloss s.n. New Guinea (S), Mt Carstensz, 3200–3810m (BM).

Flags

Occurs in Countries: ID Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Vireya Habit: Non-Tree Fl. Colour: pink, red

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:144

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Rhododendron collettianum Aitchison & Hemsley

Shrub to 1 m. Leaf-bud scales deciduous. Leaves ± elliptic, 30-40 X 13-17 mm, rounded to the base, tapered to the acute, mucronate apex, pale green and elepidote above, pale greenish brown to brown with dense, overlapping and ± plastered scales all of the same golden brown colour beneath. Inflorescence somewhat elongate, c. 16-20-flowered, pedicels short, lepidote. Calyx lobes 5-5-5 mm, sparsely lepidote outside, margins lacerate-ciliate with loriform setae, inner surface puberulent. Corolla white (often pink in bud), funnel-hypocrateriform, tube 10-13 mm, lobes 6-8 mm, glabrous and elepidote outside, tube pilose within. Stamens 8-10. Ovary lepidote. Capsule lepidote, c. 5 mm, scarcely exceeding the calyx

Habitat: Steep rocky and stony slopes

Distribution: Afghanistan, Pakistan

Altitude: 3050-3900m

Illustrations:

Nomenclature

Type: Described from Afghanistan (Shendtoi to ridges of Sikaram 10-13000 ft)

Flags

Occurs in Countries: AF, PK Altitude Ranges: 3,000 - 4,000m Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: pink

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):158

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Rhododendron comisteum Balfour f. & Forrest in Notes R.B.G. Edinb. 11: 42 (1919). Type: China

Dwarf shrub, 0.6-1m. Leaves elliptic to obovate, 3-5 X 1.2-1.5cm, 2.5-3.5 X as long as broad, apex apiculate, base cuneate, lower surface with a dense bistrate indumentum, the upper layer red-brown, loosely lanate-tomentose, the lower compacted; petioles c.0.5cm, brown-tomentose. Inflorescence 6-10-flowered; rhachis c.5mm; pedicels c.lOmm, brown-tomentose. Calyx c.0.5mm, brown-tomentose. Corolla deep rose, with a few flecks, c.35mm. Ovary rufous-tomentose. Capsule not known.

Habitat: Open pasture, stony slopes

Distribution: China (SE Xizang, NW Yunnan)

Altitude: 3950-4250m

Notes

The shape of the corolla is not clear in the herbarium specimens available so the affinities of this species are not certain. It does, however, resemble R. proteoides in its vegetative characters.

Flags

Occurs in Countries: CN Altitude Ranges: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: rose

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):346

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Rhododendron commonae Foerster

Compact, stiff, often flat-topped shrub, to 6m. Sometimes forming a thick woody basal burl from which numerous epicormic shoots arise. Twigs c.3mm in diameter, rounded or angular, green or red, stellate-scaly and minutely short-hairy; internodes 1.5–4.5cm. Leaves spir­ally arranged, or in very loose pseudowhorls, clustered more densely in the upper part of the internodes. Blade 10–43 x 8–22mm, elliptic to obovate-elliptic, narrowly obovate or in the high altitude forms almost circular; apex obtuse to rounded with a conspicuous apical gland which is sometimes extended into a down-turned point; margin flat or slightly revolute, cartilaginous and distinctly crenulate; base broadly tapering; shiny green and glabrescent above although the scales often leaving blackish pits; beneath, paler-green sub-densely brown scaly. Scales rounded to lobed, with small centres, impressed into the leaf surface and leaving distinct pits where they have fallen off. Mid-vein impressed above, broad and obtusely prominent in the lower ½ beneath, less so distally; lateral veins 4–6 per side, irregular, curved ascending, slightly impressed above in fully mature leaves, faintly raised or hardly visible beneath, reticulation inconspicuous. Petiole 2–4 x 1–2mm, grooved above and slightly flattened, scaly and obscurely shortly hairy. Flower buds to 15 x 12mm, green, the bract apices standing out as short points. Bracts to 15 x 11mm, the outer ones subulate, intermediate ovate-acuminate, abruptly subulate in the upper ¼–½, innermost ones obovate-spathulate, shining, glabrous or scaly along the dorsal midline and at the apex (never hairy!), fringed with scales. Bracteoles to 12 x 1mm, linear. Inflorescence of 4–6-flowered open umbels. Flowers half-hanging to semi-erect. Pedicels 8–18 x c.1.5mm, laxly to densely brown-stellate-scaly, without hairs or with minute papillose hairs between the scales and sometimes some longer hairs just under the calyx. Calyx c.4mm in diameter, oblique, scaly at the base, deeply 5-lobed, lobes narrowly triangular or sometimes linear-subulate up to 10mm, glabrous, or occasionally long-hairy at the apex, irregular in both shape and length, sub-persistent. Corolla 20–35 x 27mm, tubular, oblique and curved, (rarely straight), deep red to purplish, pink, pale yellow or white; tube 25–30 x 6–7 x 10–12mm, laxly to sub-densely stellately scaly outside, glabrous or shortly hairy inside, swollen at the base and conspicuously grooved in the proximal ½; lobes 10–11 x 9–10mm, sub-spathulate-circular, spreading to reflexed and overlapping to c.1⁄3. Stamens exserted to 10mm, loosely arranged in the upper ½ of the flower; filaments linear, purplish-pink, glabrous or laxly shortly papillose-hairy; anthers obovate-oblong, 2–2.3 x 1mm. Disc prominent, glabrous. Ovary 4–5 x 2–3mm, conical to sub-cylindrical, densely covered with short slightly distally directed, silvery hairs which cover small scales; style glabrous or with some hairs for the basal 5mm, ultimately as long as the stamens, on the upper side of the tube, moving to a central position as the stigma becomes receptive; stigma obliquely globose. Fruit 10–20 x 6–8mm, ellipsoid, standing erect, sub-densely short-hairy and scaly. Seeds c.3mm, the tails included.

Habitat: Terrestrial in grassland at the edge of Papuacedrus forest, in open semi-swampy places, also on crests of high ridges, stony ground. Becoming very small-leafed at high altitudes.

Distribution: Indonesia, New Guinea (W), Mt Jaya. Papua New Guinea, Star Mts, Yobobos, Mt Sugarloaf, Sirunki, Yogonda, Mt Hagen area, Tomba, Kubor Mts, Mt Wilhelm lakes area, Mt Michael, Fini­sterre Mts, Sarawaket Mts.

Altitude: 1800-4000m

Notes

Said to be named after the author’s wife!

Van Royen & Kores (1982) reduced R. pseudonitens to this species on the basis of field work which showed the size difference between them was untenable. They also recorded wild hybrids with R. culminicola and R. womersleyi in the Finisterre Mts and with R. macgregoriae in the Tari Gap.

Nomenclature

Type: Keysser s.n. Papua New Guinea, Morobe District, Mt Saruwaged, (‘Bolan’) (B†, BM).

Synonymy: R. stonori Sleumer, Reinwardtia 1960. 5: 155. R. nitens Sleumer, Reinwardtia 1960. 5: 162, non Hutchinson, 1936. R. pseudonitens Sleumer, Blumea 1961. 11: 124.

Flags

Occurs in Countries: ID, PG Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Vireya Habit: Non-Tree Fl. Colour: pink, red, white, yellow

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:219

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Rhododendron commutatum Sleumer

Shrub or small tree to 3m, growing with dense-packed, slender stems. Twigs 2–4mm in diameter, rounded, densely covered with sub-stellate reddish-brown scales when young; internodes 3–12cm. Leaves 2–5 together in pseudowhorls. Blade 80–170 x 20–55mm, elliptic; apex elongate, sometimes abruptly acuminate, sub-acute; margin flat or very slightly revolute; base broadly and acutely tapering, (never rounded), sometimes the sides unequal, sub-persistently scaly above, minutely rugose by inflated epidermis cells, persistently laxly to sub-densely scaly beneath. Scales minute, marginal zone sub-stellately lobed; centres small and slightly impressed. Mid-vein very narrow and distinctly depressed above, as thick as the petiole, and strongly prominent beneath, often more densely scaly than the surrounding leaf; lateral veins 10–14 per side, spreading at almost 90°, straight below, curved and obscurely anastomosing before the margin, with additional less distinct veins, parallel, faintly impressed above, minutely raised or inconspicuous beneath, reticulation dense, visible above only. Petiole 10–15 x 1.5–2mm, flattened and grooved above, densely scaly. Bracts to 20 x 7mm; outer bracts narrowly ovate-acuminate, extended at the apex into a fine sharp point, scaly along the outside middle line distally, glabrous at the margin, inner bracts much narrower, nearly linear. Bracteoles c.15mm, filiform, laxly scaly. Inflorescence 3–5-flowered, an open umbel, the flowers semi-erect. Pedicels 10–20 x c.1mm, laxly sub-stellately scaly, not hairy. Calyx c.4mm in diameter, obliquely disc-shaped, shortly and bluntly 5-lobed, densely scaly outside. Corolla 50–65mm, funnel-shaped, bright red with purplish-pink flushed throat, lobed to c.1⁄3; tube 30–40 x 4–5 x c.15mm, lobed at the base, laxly minutely sub-stellately scaly outside, laxly short-hairy in the proximal ½ inside; lobes 20–27 x 15–24mm, half-spreading, broadly obovate-spathulate or sub-circular. Stamens unequal, exserted to c.10mm; filaments linear, sub-densely papillose-hairy proximally, papillose in the middle, glabrous in the distal 1⁄3; anthers 3–3.5 x c.1mm, oblong. Disc glabrous below, shortly hairy on the upper margin. Ovary 7–8 x c.2mm, sub-cylindrical, greyish long-hairy with distally directed hairs and densely scaly (the scales covered by the hairs), abruptly contracted distally; style thick, densely sub-patently hairy nearly to the top, less densely scaly, nearly as long as the corolla; stigma thick-rounded. Fruit c.80 x 4mm, narrowly cylindrical, curved, laxly hairy and densely scaly.

Habitat: Mostly terrestrial in swampy jungle or white sand podsols at low elevations in shaded habitats.

Distribution: Malaysia (Borneo), Sarawak and Sabah. Brunei.

Notes

Latin – commutatus – change, presumably an allusion to the changed status of the original collection.

Nomenclature

Type: Beccari P.B. 2322. Borneo, Sarawak, Lundu (FI, A, K, P, S).

Synonymy: R. gracile (non Low ex Lindl.) Beccari, Malesia 1878. I: 203.

Flags

Occurs in Countries: MY Subgenus: Vireya Habit: Tree Fl. Colour: red

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:271

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Rhododendron comparabile Sleumer

Erect shrub to 2m. Twigs 2–4mm in diameter, semi-rounded, laxly and deciduously sub-stellately scaly when young, sometimes whitish; internodes 2–11cm. Leaves 4–5 together in pseudowhorls. Blade 35–90 x 25–50mm, elliptic to sub-obovate-elliptic; apex broadly tapering or very shortly sub-abruptly acuminate, obtuse, sometimes rounded; margin narrowly but distinctly revolute; base broadly tapering, glabrescent above when mature, laxly, sub-persistently scaly beneath. Scales minute, marginal zone irregularly sub-stellately lobed; centre slightly impressed. Mid-vein narrowly impressed above, thick and obtusely prominent beneath; lateral veins 5–9 per side, spreading, sometimes irregular, often divided before the margin, mostly sub-parallel to each other and distinctly curved-anastomosing, slightly impressed above, somewhat raised beneath, reticulation faintly impressed above in old leaves, often inconspicuous. Petiole 10–23 x 1–2mm, semi-rounded, grooved above. Bracts to 20 x 15mm; outer bracts ovate, sub-acuminate, or circular, scaly along the midline distally outside; inner bracts obovate to spathulate, glabrescent or glabrous apart from marginal scales. Bracteoles 15 x 0.5–1.5mm, linear-spathulate, glabrous. Inflorescence an open 8–13-flowered umbel. Pedicels 20–30 x c.1mm, densely sub-stellately scaly. Calyx c.3mm in diameter, obliquely disc-shaped, shortly and bluntly 5-lobed, scaly outside. Corolla 40–48 x 50mm, funnel-shaped, white, scented; tube c.25 x 5–6 x 8–12mm, straight, sub-cylindrical, lobed at the base, laxly to sub-densely covered with minute sub-stellate scales outside, shortly hairy inside; lobes 15–20 x 15–20mm, broadly obovate or sub-circular, spreading. Stamens sub-equal, exserted; filaments linear and laxly patently hairy in the lower 2⁄3, more filiform and glabrous distally; anthers 3–3.5 x 0.8mm, narrowly oblong. Disc low, glabrous. Ovary 5–6 x c.2mm, sub-cylindrical, densely covered with forwardly directed hairs which cover the scales, tapering distally; style slightly shorter than the stamens, densely hairy and scaly for the proximal ¾, scaly at the apex; stigma deeply 5-lobed. Fruit 30–35 x 5–6mm, sub-cylindrical. Seeds very narrow, 4–5mm including the long tails.

Habitat: Scattered in stiff scrub on the summit and on cliffs.

Distribution: Papua New Guinea, Milne Bay District, Sudest I., on Mt Riu

Altitude: 600-800m

Notes

Latin – comparandus – worthy of comparison, alluding to its supposed relationship with R. lochae (see below).

Sleumer (1966) noted: ‘Much related to R. lochae F. v. M. from NE Queensland (the only Rhododendron in Australia [at that time]), which, however, has red corollas, laxly hairy ovary (the scales thus clearly visible) and 2–5 (rarely up to 7) flowers per umbel’. It would be interesting to know if DNA analysis supported this view.

Nomenclature

Type: Brass 27861, 27 Aug. 1956. New Guinea, SE, Milne Bay District, Sudest Isl., Mt Riu, summit, 800m (L, A, K, LAE, PNH, S, US).

Flags

Occurs in Countries: PG Altitude Ranges: 0 - 1,000m Subgenus: Vireya Habit: Non-Tree Fl. Colour: white

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:299

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Rhododendron complexum Balfour f. & W. W. Smith

Fastigiate or rounded, much branched shrub, 8-60 cm. Leaves 3.5-11 x I -8-6 mm, broadly or narrowly elliptic to ovate, apex obtuse or rounded, mucro small or absent, base cuneate or truncate, undersurface uniformly ferrugineous with contiguous scales. Inflorescence 3-4(-5)-flowered, pedicels lepidote, 0-5-7.5 mm. Calyx obsolete to less than 1 mm, rarely to 2 mm, lobes deltoid, rounded or strap-shaped, margin lepidote and/or ciliate. Corolla pale lilac to rosy purple, usually narrowly funnel-shaped, 9-13 mm, tube 4-6 mm, pubescent inside and occasionally outside. Stamens 5-6(-8), filaments pubescent towards the base. Ovary lepidote, style usually short (up to 3 mm), rarely longer (6-8 mm), glabrous or slightly pubescent towards the base. Capsule c. 5 mm, ovoid to subrotund, lepidote.

Habitat: Alpine screes, rocks and stony slopes

Distribution: China (N Yunnan)

Altitude: 3400-4600m

Nomenclature

Type: China, Yunnan, Chungtien plateau, 3350-3650 m, Forrest 12520 (holo. E, iso. K)

Flags

Occurs in Countries: CN Altitude Ranges: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: lilac, purple

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):99

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Rhododendron comptum C.H.Wright

Notes

Latin – comptus – adorned, presumably alluding to the plant being covered with flowers.

Nomenclature

Type: Giulianetti s.n., 1896. New Guinea, Owen Stanley Range, Mt Scratchley (K).

Flags

Occurs in Countries: PG Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Vireya

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:137

Rhododendron comptum var. comptum

Low erect shrub with several branches arising in­dependently from subterranean stems. Twigs 2–3mm in diameter, firm, angular and longitudinally striate, densely covered with sessile scales initially, glabrescent and smooth with age, often with conspicuous lateral buds; internodes 2–8cm. Leaves loosely spirally arranged, mostly in the upper ½ of the internode, sometimes over the whole length, semi-erect. Blade 18–30 x 5–9mm, narrowly elliptic to elliptic or obovate-elliptic; apex shortly tapering, sub-apiculate, or sometimes nearly rounded; margin minutely crenulate by impressed scales, not revolute; base tapering, densely scaly on both sides initially, glabrescent and shining above with age, below more persistently scaly. Scales very dense, touching and often overlapping each other, flat, thin, small, brown initially, becoming silvery with age; centre impressed, leaving a pitted surface when the scales have gone. Mid-vein a little impressed above, and slightly and obtusely raised beneath, obscure apically; lateral veins not visible. Petiole 0.5–2 x c.1.5mm, flattened and grooved above, scaly. Outer bracts to 20 x 10mm, ovate-elliptic, sub-­acuminate, inner ones elliptic to elliptic-obovate, scaly on a broad midline outside, glabrous elsewhere. Bracteoles linear, glabrous, c.15mm. Inflorescence 3–5-flowered, the flowers hanging vertically. Pedicels very densely scaly, without hairs, 12–18 x 1–1.5mm. Calyx c.3.5mm in diameter, shortly cup-shaped, oblique, forming an angle with the pedicel, densely scaly outside, obscurely and bluntly lobed, sometimes with one lobe more distinct. Corolla tubular below, campanulate distally, c.28 x 20mm, bright red; tube 15–18 x 4–5 x 6–7mm, laxly scaly outside, glabrous inside; lobes 7–9 x 7–9mm, sub-circular, spreading. Stamens within the mouth; filaments linear, light yellow, glabrous; anthers 1.3–1.5mm, inwardly curved, light brown, obovate to sub-orbicular. Disc glabrous. Ovary 3–4 x 2.5–3mm, very densely scaly, conical, tapering or somewhat abruptly contracted distally; style as long as the corolla, thick, scaly proximally for ¼–1⁄3, glabrous distally; stigma large, 5-lobed. Fruit c.15 x 6mm, ovoid.

Distribution: Papua New Guinea, Owen Stanley Range: Mts Scratchley, Victoria and Albert Edward

Altitude: 3000-4000m

Notes

The species is fairly distinctive, with its scattered elliptic leaves with no obvious lateral veins but often drying with oblique lateral folds on the undersides of the blades. This has been confused with R. giulianettii but that species has much broader leaves in relation to length, with rounded rather than tapering bases. Rhododendron giulianettii also commonly (but not always) has leaves with 1–2 lateral veins per side, visible.

Rhododendron comptum var. trichodes Sleumer

Differing only in that the ovary is hairy, as well as densely scaly. Described with bright red flowers. Fruit 10–12 x 6–7mm, becoming erect with persistent styles. Seeds 20–25mm, without tails 0.9mm, the longest tail 0.9mm.

Distribution: Papua New Guinea, Mt Albert Edward, cliffs in open grassland and terrestrial on a steep, boggy slope

Altitude: 3600-3800m

Notes

Greek – tricho – hairy, alluding to the hairy ovary which distinguishes this from the type variety.

Nomenclature

Type: Brass 4346. New Guinea, Central Dist., Mt Albert Edward (L, A, BO).

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Rhododendron concinnoides Hutchinson & Kingdon Ward

Very similar to R. monanthum, differing essentially only in its purple corolla. INDIA (Arunachal Pradesh)

Notes

Known only from the type collection, this species is a purple-flowered equivalent of R. monanthum. Its distinctness is dubious (purple/yellow corolla colour variation is known in other species, e.g. R. lepidotum, see p. 149) and further material is necessary before its status can be settled.

Nomenclature

Type: Assam, Delei valley, 8000-11000 ft, Kingdon Ward 8578 (iso. E)

Flags

Subgenus: Rhododendron Habit: Non-Tree

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):61

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Rhododendron concinnum Hemsley

Shrub, 0-5-2 m. Leaves ovate or elliptic, 35-60 x 18-32 mm, rounded to cordate at the base, acute to slightly acuminate at the apex, upper surface lepidote (scales sometimes deciduous), puberulent along the midrib, lower surface grey or brownish with numerous contiguous or almost contiguous large, flat, broadly rimmed scales with a tendency to dimorphism in colour—golden and brown. Inflorescence 2-4-flowered; pedicels (5-)7-13 mm, lepidote. Calyx minute, variably lobed, ciiiate with loriform and filiform-acicular hairs, rarely glabrous. Corolla purple or reddish purple, rarely pale, 20-30 mm, tube 8-15 mm, lepidote on the tube outside, pubescent within the tube. Stamens 10, filaments pubescent towards the base. Ovary lepidote, sometimes minutely pubescent at apex. Style glabrous or puberulent. Capsule lepidote, 8-14 mm

Habitat: Forests and thickets

Distribution: China (NW, SW, C & E Sichuan, W Hubei)

Altitude: 2300-4500m

Illustrations:

Notes

A rather variable species known from material that is, for the most part, poor. Leaf shape and size vary, as does the colour of the leaf undersurface. It is, however, reasonably distinct on the basis of its broad leaves and lepidote, purple corolla. R. apiculatum was based on a poor specimen collected by Wilson, and is identical with R. concinnum except that the extant fragment of the corolla is not lepidote. The varieties recognised by Davidian have no significance other than in horticulture. I have seen no material of R. hutchinsonianum Fang, Acta Phytotax. Sinica 2:83, 1953 (type: Szechuan, Erh-lang-shan, Tien chuan hsien, Hu & Ho 10148, holo. CHENGDU). From the description, it is merely a variant of R. concinnum.

Nomenclature

Type: China, Szechuan, summit of Mt Omei, Faber (holo. K)

Synonymy: R. yanthinum Bureau & Franchet, Journ. de Bot. 5:94 (1891). Type: China, Szechuan, sur les montagnes au sud du Tatsienlu, Henri d'Orleans (holo. P—n.v., iso. E). R. benthamianum Hemsley, Gard. Chron. 47:4 (1910). Type: China, Szechuan, Wilson 1878 (holo. K). R. coombense Hemsley, Bot. Mag. 135: t. 8280 (1909). Type: a cultivated specimen (holo. K). R. apiculatum Rehder & Wilson, PI. Wils. 1:519 (1913). Type: China, Szechuan, west and near Wen chuan hsien, Wilson 3422 (iso. K). R. yanthinum var. lepidanthum Rehder & Wilson, Ioc. cit. Type: China, Szechuan, west and near Wen chuan hsien, 2500 in, vii 1908, Wilson 3419 (n.v.). R. laetevirens [Balfour f. ex] Hutchinson, The Species of Rhododendron, 781 (1930) in syn. R. pseudoyanthinum [Balfour f. ex] Hutchinson, op. cit.: 783. Type: as for R. yanthinum var. lepidanthum. R. concinnum var. benthamianum (Hemsley) Davidian, R.H.S. Rhodo. Yearbook 17:194 (1963). R. concinnum var. pseudoyanthinum (Balfour ex Hutchinson) Davidian, loc. cit.

Flags

Occurs in Countries: CN Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: purple, red

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):75

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Rhododendron coriaceum Franchet

Shrub or small tree, 2-7.5m. Leaves oblanceolate, (12-) 16-25 x 4.8 -6.2cm, 2.5-4 x as long as broad, apex rounded, minutely apiculate, base cuneate, upper surface glabrescent, smooth, lower surface covered with a dense bistrate indumentum, the lower layer compacted, the upper whitish or fawn to pale cinnamon, composed of scarcely fimbriate, broadly cup-shaped hairs; petioles 2-3cm, terete, sparsely whitislj-tomentose. Inflorescence 15-20-flowered; rhachis 10-15(-30)mm; pedicels 20-30mm, sparsely brown-tomentose. Calyx c.lmm, lobes minute. Corolla (5-)7-lobed, funnel-campanulate7; white, sometimes flushed with rose, with a crimson basal blotch, sometimes also with flecks, 35-40mm. Stamens (10-)14. Ovary densely rufous-tomentose. Capsule 18-25 x 4mm, straight or curved.

Habitat: Conifer forests, Rhododendron thickets

Distribution: China (NW Yunnan, SE Xizang)

Altitude: 3000-4000m

Illustrations:

Notes

R. coriaceum is allied to R. rex but may be distinguished from subsp. rex, which also has a pale leaf indumentum, by its more slender leaves and its more westerly distribution. Some forms of subsp. fictolacteum approach R. coriaceum in the size of their leaves but have a consistently darker indumentum.

Nomenclature

Type: China, NW Yunnan, environs de Tsekou, Soulie 1021 (E, K), 1022 (E, K), 1024 (E)

Synonymy: R. foveolatum Rehder & Wilson in Sargent (ed.), PL Wilsonianae 1: 537 (1913). Type: China, NW Yunnan, Tsekou, Mombeig 3 (E)

Flags

Occurs in Countries: CN Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Tree Fl. Colour: crimson, rose, white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):258

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Rhododendron cornu-bovis Sleumer

Small straggling shrub to 2m. Twigs c.1mm in diameter, rounded, tips flattened and densely covered with reddish-brown, sub-stellate scales; internodes 2–4cm. Leaves 4–6 together in pseudowhorls. Blade 25–40 x 8–14mm, obovate-elliptic to obovate; apex broadly tapering, obtuse or rounded; margin slightly recurved; base tapering, scaly on both sides at first, quickly glabrescent above, persistently sub-densely scaly beneath. Scales large, flat, irregularly stellately divided in the marginal zone; centre slightly impressed. Mid-vein grooved above, prominent beneath; lateral veins 3–4 per side, inconspicuous, often obscure beneath. Petiole 2–4mm, scaly. Bracts to 8 x 5mm, broadly ovate to ovate-elliptic, obtuse, glabrous outside, except for the marginal scales. Bracteoles c.5mm, filiform, laxly scaly. Inflorescence 2–3-flowered. Pedicels 10–14 x 0.5–0.7mm, slender, sub-densely stellately scaly and sparsely, shortly patently hairy. Calyx c.2.5mm in diameter, disc-shaped, oblique, scaly and shortly hairy outside, indistinctly 5-lobed. Corolla c.25 x 20mm, obliquely tubular-funnel-shaped, pink to red; tube 12–14 x 4–5 x 6–8mm, sub-densely to laxly covered with reddish-brown sub-stellate scales outside, laxly hairy inside, slightly curved; lobes 9–10 x 6–7mm, spreading, obovate-spathulate. Stamens exserted to c.5mm, sub-equal; filaments filiform, laxly patently hairy for the proximal 2⁄3, glabrous distally; anthers c.1.6mm, broadly oblong. Disc prominent, glabrous. Ovary c.5 x 2mm, sub-cylindrical, densely short-hairy and scaly, the scales covered by the hairs, tapering distally; style oblique, laxly patently hairy in the proximal ½, without scales, glabrous distally, nearly equalling the corolla in length; stigma sub-globose. Fruit (sub-mature) 22 x 4mm, sub-fusiform-cylindric, curved, densely hairy and scaly.

Habitat: Reported to be common in mossy forest and shrubberies

Distribution: Indonesia, New Guinea (W), Waigeou I., (W of Vogelkop), top of Mt Nok (Buffelhoorn)

Altitude: Around 860m

Notes

Latin – cornu – horn; bovis – an ox. After the Dutch name of Mt Nok where it was collected.

Nomenclature

Type: Cheesman 1192, 17 June 1938. New Guinea, Weigeo I., top of Mt Nok (Buffelhoorn), E shore of Majalibit Bay, c.860m (BM).

Flags

Occurs in Countries: ID Altitude Ranges: 0 - 1,000m Subgenus: Vireya Habit: Non-Tree

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:219

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Rhododendron correoides J.J.Sm.

Shrub with erect branches, to 4m. Twigs round to angular, at first densely covered with scales, which give a grey appearance; internodes 1–8cm often with conspicuous rounded lateral buds. Leaves either scattered in loose, or crowded in distinct 5–7-leafed, pseudowhorls. Blade 20–35 x 8–17mm, elliptic or sub-obovate, rarely ovate-elliptic; apex broadly obtusely tapering, sometimes rounded, apiculate with a small terminal gland; margin thickened and crenulate by impressed scales; base very broadly tapering to rounded, densely scaly initially on both sides, glabrescent later above and then with a pitted surface; very densely and more persistently scaly beneath. Scales overlapping with broad transparent, lobed marginal zones which eventually disappear and small to moderately sized centres which are impressed, leaving pits. Mid-vein slightly impressed above, bluntly raised beneath especially in the proximal part, disappearing distally, or sometimes entirely inconspicuous; lateral veins 3–5 per side, curved-ascending, faintly impressed or often obscure above, indistinct beneath. Petiole 3–12 x c.2mm, semi-rounded, grooved above, densely scaly. Buds 15–20 x 8–11mm, narrowly ovate with a slender acute apex and with spreading tips. Bracts to 20 x 10mm; outer bracts ovate-acuminate, sub-acute with a few scales outside near the midline and margins, glabrous elsewhere but often with a greyish waxy deposit; inner ones narrowly ovate to obovate-spathulate, membranous and shiny, glabrous. Bracteoles 10–15mm, linear-sub-­spathulate, glabrous. Inflorescence an open, 3–5-flowered umbel, the flowers hanging vertically, occasionally half-hanging. Pedicels 10–20 x c.1mm, very densely scaly, without hairs, forming an angle with the calyx. Calyx 2.5–3mm in diameter, very shortly cup-shaped, oblique, densely scaly outside, obscurely lobed. Corolla 20–32 x 20–25mm, tubular below, slightly dilated distally, yellow or orange, without scent; tube 12–22 x 4–8 x 6–12mm, sub-densely or laxly scaly outside, glabrous inside; lobes 6–11 x 8–9mm, broadly elliptic to sub-circular, semi-erect, overlapping to halfway, scaly outside away from the margins. Stamens unequal, irregularly clustered around the mouth of the flower; filaments linear, glabrous; anthers 2–2.5 x 1.3–2mm, broadly obovate-oblong. Disc glabrous. Ovary c.4 x 2.5–3mm, conical, densely scaly; style thick, scaly at the very base, glabrous otherwise, as long as the corolla, becoming exserted; stigma thick, 5-lobed. Fruit c.15–20 x 4–5mm, sub-cylindrical, apex long-­tapering, base shortly tapering, becoming erect before maturity. Seeds 4–4.8mm, without tails 1mm, the longest tail c.2.1mm, one tail often much broader than the other.

Habitat: Sub-alpine forest, marginal forest shrubberies and in open vege­tation, also on ridge crests, commonly on mossy or peaty soil, locally abundant

Distribution: Indonesia, New Guinea (W), the Main Range from Mt Jaya (Carstensz), Hubrecht and Orange Mts to Mt Trichora (Wilhelmina).

Altitude: 3100-4300m

Notes

Resembling Correa, Australian trees in the Rutaceae.

Introduced into cultivation in 1993 by Paul Smith, it grows weakly as a leggy shrub in Edinburgh although flowering regularly. It is one of the species used in the Mt Jaya mine to recolonise disturbed ground and spoil heaps as it grows well at high altitude. It is not a spectacular plant, the flowers being rather small. It comes in two colour forms, yellow and orange, although intermediates may occur.

Nomenclature

Type: Pulle (Versteeg) 2435, 7 Feb. 1913. W New Guinea, Hubrecht Mts (lectotype) (L, BO, K, U).

Synonymy: R. coniferum Wernham, Trans. Linn. Soc. London, II, Bot. 1916. 9: 97.

Flags

Occurs in Countries: ID Altitude Ranges: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Vireya Habit: Non-Tree Fl. Colour: orange, yellow

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:135

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Rhododendron coryanum Tagg & Forrest

Shrub or small tree, 2.5—6m. Leaves elliptic to oblanceolate, 8.5—16 x 2.2-4cm, c.4 x as long as broad, apex acute to acuminate, glabrous above, lower surface with a thin compacted silvery to fawn unistrate indumentum embedded in a surface film and intermixed with a few stipitate glands; petioles 1.5—2cm, floccose, with a few shortly stipitate glands. Inflorescence 20-30-flowered; rhachis 15-30mm; pedicels 30-35mm, sparsely dendroid-hairy and glandular. Calyx 2-3mm, lobes triangular, glandular. Corolla funnel-campanulate, whitish with crimson flecks, 25—30mm. Ovary glabrous or with a few whitish simple hairs; style glabrous. Capsule 20-25 x 4-6mm, cylindrical, curved to ± circinnate.

Habitat: Fir forests. Rhododendron thickets

Distribution: China(NW Yunnan & adjacent SE Xizang)

Altitude: 3650-4400m

Notes

The ± glabrous ovary and many-flowered inflorescence distinguish this from the remaining species of the subsection.

Nomenclature

Type: China, SE Xizang, Salween/Kiu-chiang divide, NW of Si-chi-to, vi 1932, Forrest 21693 (holo. E); Forrest 22889-Iater collection (fruiting) (E)

Flags

Occurs in Countries: CN Altitude Ranges: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Tree Fl. Colour: crimson

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):324

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Rhododendron cowanianum Davidian

Deciduous shrub, 0.3-2.3 m. Shoots pale brown, glabrous, ± elepidote. Leaves thin, oblong-elliptic, broadly elliptic or obovate, 42-65 X 22-30 mm, margins loriform-ciliate, upper surface dark green, lepidote, filiform-acicular pubescent along the veins, lower surface pale green, lepidote with distant, pale brown, broadly rimmed scales. Inflorescences 3-5-flowered, pedicels 10-20 mm, lepidote and sparsely puberulent. Calyx lobes reddish, lepidote, glabrous or rarely with a few short loriform cilia, 4-6 mm. Corolla purplish pink, 14-20 mm, very sparsely lepidote outside. Stamens 10. Ovary lepidote. Capsule ovoid-cylindric, lepidote, 8-11 mm

Habitat: Open slopes in forest

Distribution: Nepal

Altitude: 3200-3950m

Illustrations:

Notes

A distinct species of rather uncertain affinities. It was originally placed in subsection Trichoclada (Trichocladum series) because of its deciduous leaves, but it differs from that group in scale type and inflorescence, and is more closely allied to R, lepidotum.

Nomenclature

Type: Nepal, Langtang lateral valley, 3650 m, Polunin 175 (holo. BM, iso. E)

Flags

Occurs in Countries: NP Altitude Ranges: 3,000 - 4,000m Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: pink

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):150

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Rhododendron crassifolium Stapf

Notes

Latin – crassus – thick; folium – leaf. Alluding to the thick leaves.

Nomenclature

Type: Low s.n. North Borneo, Mt Kinabalu, 1525–2745m (K).

Synonymy: R. crassinervium Ridl., J. Str. Br. R. As. Soc. 1912. 63: 61. R. brevitubum J.J.Sm., Ic. Bog. 1914. 4: 253, t.381.

Flags

Occurs in Countries: ID, MY Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Vireya Fl. Colour: orange, pink, red, white

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:257

Rhododendron crassifolium var. crassifolium

Shrub to 2.5m. Twigs 3–5mm in diameter, sparsely scaly, quickly glabrescent; internodes 1.5–15cm. Leaves spirally arranged or in lax pseudowhorls of 3–4 together. Blade 80–140 x 40–80mm, elliptic, or broadly elliptic, occasionally obovate-elliptic; apex obtuse or rounded, sometimes shortly obtusely acuminate; margin entire, flat; base broadly tapering, rounded or truncate, sometimes slightly cordate; initially scaly on both sides, glabrescent and blackish punctate above when mature, scaly for longer beneath. Scales lax, small, flat, irregularly lobed; centre minute, faintly or not impressed. Mid-vein very strongly raised above for the proximal ½–2⁄3, smooth near the apex, only weakly raised beneath or completely smooth; lateral veins 8–12 per side, sub-parallel, broadly spreading to almost a right angle, anastomosing before the margin, slightly raised above and smooth below when fresh, raised on both sides when dry, the surface smooth or distinctly rugosely puckered above, reticulation dense. Petiole 7–15 x 5–8mm, somewhat flattened, not grooved, sparsely scaly. Flower buds to 45 x 25mm, ovate, acute to obtuse, pale translucent pink or whitish, with the outer bracts standing vertically away from the buds or appressed. Bracts ovate-acuminate, glabrous, to 25 x 10mm. Bracteoles to 20mm, linear, glabrous. Inflorescence 8–20-flowered in a complete umbel, semi- erect to half-hanging. Pedicels 20–60 x c.2mm, sparsely scaly. Calyx 3–4mm in diameter, a fleshy ring, glabrous. Corolla 25–30 x 25–45mm, shortly funnel-shaped, pink, red or more rarely orange or white; tube 12–15 x 6–10 x 12–15mm, glabrous outside, sparsely hairy inside, distinctly 5-pouched at the base; lobes 12–22 x 13–19mm, obovate-elliptic, not, or overlapping up to ½, often with the lateral margins revolute. Stamens dimorphic, 12–20mm, regularly arranged around the mouth, only the longest slightly exserted up to 2mm; filaments linear, densely sub-patently hairy in the proximal ¼–1⁄3, filiform and glabrous distally; anthers 2.5–3 x 1.3mm, sub-elliptic. Disc prominent, glabrous. Ovary 5–6 x 2.5–3mm, glabrous, or with some minute scales depressed into pits in the surface, abruptly contracted distally; style 3–4mm, centrally placed, glabrous; stigma 2–3mm in diameter, dark red, 5-lobed. Fruit 18–25 x 5–6mm. Seeds 4–5mm, without tails 0.8mm, the longest tail 2.8mm.

Habitat: Epiphytic in deep shade of mossy forest but also terrestrial on open landslides, locally common and widespread

Distribution: Malaysia (Borneo), Sabah, Kinabalu, Crocker Range, Mt Trus Madi. Sarawak, Mt Mulu, Mt Murud, Mt Dulit, Upper Limbang R., Mt Derian. Indonesia, Kalimantan (Borneo), C Mt Liang Gagang, Mt Mili.

Altitude: 1200-2200m

Notes

Rhododendron crassifolium is a variable but nevertheless very distinct species. Hybrids with R. stenophyllum have been recorded and are very similar to R. nervulosum. Rhododendron x planecostatum is the hybrid with R. bagobonum. Rhododendron brevitubum was reduced to synonymy by Argent et al. (1988). It differed by the hairs inside the corolla tube being in 5 distinct vertical stripes. The hairs inside the corolla of R. crassifolium are commonly in 5 indistinct stripes and in other ways the plants are very similar: at best R. brevitubum could be considered as a local variant.

Rhododendron crassifolium var. pseudomurudense (Sleumer) Argent

Differing only in the glabrous filaments.

Habitat: Common epiphyte in primary forest.

Distribution: Indonesia, Central East Borneo, Mt Kemul. Malaysia (Borneo), Sarawak, Mt Murud

Altitude: 1600-1850m

Notes

Latin – pseudo – false; murudense – of Mt Murud. The original Smith collection having been from Mt Murud.

Nomenclature

Type: Endert 4323, 18 Oct. 1925. Borneo, Central East, W Kutei, Mt Kemul (BO, L).

Synonymy: R. murudense (non Merr.) J.J.Sm., Bull. Jard. Bot. Buit. III, 1935. 13: 449. R. murudense Merr., Sarawak Mus. J. 1928. 3: 542. R. pseudomurudense Sleumer, Reinwardtia 1960. 5: 189.

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Rhododendron crenulatum [Hutchinson ex] Sleumer

Shrub to 1 m. Young branches loriform-setose, the setae persistent. Leaves oblong-elliptic, (25-)30-40 x (12-)15-20 mm, cuneate at the base, rather abruptly narrowed to the acute apex, upper surface with the veins puberulent, margins crenulate, lower surface densely lepidote. Inflorescence 3-4-flowered, pedicels densely lepidote. Calyx 5-lobed, the lobes ± ovate, obtuse, c. 2 mm, densely lepidote, loriform-ciliate. Corolla pale yellow, c. 30 mm, tube 15 mm, lepidote and pilose near the base outside. Stamens 10, pubescent towards the base. Ovary densely lepidote, style impressed, lepidote for most of its length, densely so at the base, more laxly so above. Capsule broadly oblong, 10-13 mm, lepidote.

Distribution: Laos

Notes

Known only from the type collection.

Nomenclature

Type: Laos, prov. Tranh-Ninh, Pu Bia (103° 7' 19° 01'), summit c. 2800 m, 14 iv 1932, Kerr 21044 (holo. K; iso. BM, P-ult. n.v.)

Flags

Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: yellow

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):43

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Rhododendron cretaceum P.X.Tan

Shrub, c.1.5m; young shoots adpressed-strigose at first, soon glabrescent. Leaves dimorphic, chartaceous; spring leaves ovate, 4-5 x 2-2.3cm, c.2 x as long as broad, apex acute to shortly acuminate, base cuneate, margin ciliate towards base, upper surface initally adpressed-strigose, soon glabrescent, lower surface adpressed brownish-strigose especially on midrib; summer leaves 12-18 x 10mm, otherwise as for spring leaves; petioles 2-4mm, strigose. Inflorescence 5-6-flowered; pedicels 3-5mm, reddish strigose. Calyx densely strigose, lobes c.3mm. Corolla funnel-campanulate, white with red flecks, c.l6mm; tube c.9mm long, 5mm wide at base, hairy on outer surface, tapering. Stamens 5, filaments glabrous. Ovary densely reddish-brown-stri-gose; style strigose at base. Capsule not known.

Habitat: Woodland

Distribution: China (Guangdong)

Notes

Superficially resembling R. mariae but differing in the short, hairy corolla tube

Only known from the type

Nomenclature

Type: China, Guangdong, Rhuyuan Xian, 12 iv 1934, X.P. Gao (S.P. Ko) 54106 (holo. IBSC)

Flags

Occurs in Countries: CN Subgenus: Tsutsusi Habit: Non-Tree Fl. Colour: red, white

Chamberlain, D.F. & Rae, S.J. (1990) A Revision of Rhododendron IV Subgenus Tsutsusi. Edinburgh Journal of Botany 47(2):106

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Rhododendron crinigerum Franchet

Shrub or small tree, l-5m; young shoots with a sparse covering of shortly stipitate glands. Leaves subcoriaceous, obovate to oblanceolate, (7—)10—17 x (2.3-)3-4.2cm, 3-4 x as long as broad, apex cuspidate, base rounded, margin not ciliate, upper surface glabrous when mature, lower surface with a dense (occasionally sparse) matted fawn to red-brown tomentum composed of ramiform hairs, intermixed with stipitate glands, especially towards the base; petioles l-2cm, densely stipitate-glandular. Inflorescence 8-14-flowered; rhachis 10-15mm; pedicels 25-30mm, densely stipitate-glandular, also very sparsely hairy. Calyx 5-10mm, densely stipitate-glandular, lobes irregular, Ungulate, rounded. Corolla campanulate, white flushed pink, with at least a few purple flecks and a basal blotch. Ovary stipitate-glandular; style glabrous or glandular at base. Capsule c.15 x 6mm.

Habitat: Open pine forests, rocky slopes

Distribution: China (NW Yunnan, SE Xizang), NE Upper Burma

Altitude: 3350-4000m

Notes

R. crinigerum is less setose that the remaining species of this subsection and in this respect approaches some members of subsection Taliensia. However, in leaf shape and in leaf characters, it is closer to the remaining members of subsection Glischra.

Flags

Occurs in Countries: CN, MM Altitude Ranges: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Tree Fl. Colour: pink, purple, white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):288

Rhododendron crinigerum var. crinigerum

Nomenclature

Type: China, NW Yunnan, Tsekou, environs de Thrana, 15 v 1895, Soulie 1011 (holo. P, n.v.)

Synonymy: R. ixeunticum Balfour f. & W. W. Smith, Notes R.B.G. Edinb. 9: 240 (1916). Type: China, NW Yunnan, Kari Pass, Mekong/Yangtze divide, 12000ft, viii 1914, Forrest 12944 (holo. E).

Rhododendron crinigerum var. euadenium Tagg & Forrest

Notes

The leaves of all the specimens of var. euadenium are more glandular than those of var. crinigerum and most are less densely hairy. The type, however, is more densely tomentose. The following specimens are intermediate between the two varieties in that the lower surface of the leaves is densely tomentose but also with many stipitate glands: Rock 10967, 22504.

Nomenclature

Type: China, NW Yunnan, Salween/Kiu-chiang divide, vii 1924, Forrest 25619 (holo. E).

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Rhododendron cruttwellii Sleumer

Tree to 6m. Twigs semi-rounded, laxly to densely scaly; internodes 2.5–14cm. Leaves 5–7 together in tight pseudowhorls, with some much smaller than the others. Blade 50–100 x 20–40mm, obovate-elliptic or elliptic to broadly elliptic; apex shortly gradually acuminate, obtuse to broadly acute, sometimes with a small terminal gland; margin entire, flat; base broadly tapering, dark green above, paler and dull beneath, glabrescent above, laxly to sub-densely scaly beneath. Scales with a broad, thin marginal zone variously dentately divided; centre small, somewhat impressed and more persistent. Mid-vein raised and grooved for a few millimetres proximally otherwise slightly depressed above, raised beneath; lateral veins 8–10 per side, lower ones irregular, distinctly grooved above in the basal part, upper ones more straight and sub-parallel, curved-anastomosing with each other, smooth when fresh, prominent on both sides when dry, reticulation dense and visibly raised on both sides when dry, very distinct underneath when fresh. Petiole 6–12 x 1.5–2mm, grooved above, slightly flattened, scaly. Flower buds to 25 x 15mm, imbricate, green, smooth with the bracts appressed. Bracts to 15 x 10mm, ovate-acuminate, laxly scaly in the middle outside, also with hairs all over the outer and undersurface, glandular-ciliate. Bracteoles to 15mm, narrowly linear, glabrous. Inflorescence 4–9-flowered in erect to spreading umbels. Pedicels 10–15 x 1–1.5mm, laxly patently hairy and scaly especially in the distal 1⁄3, obliquely thickened below the calyx. Calyx c.2.5mm in diameter, membranous, indistinctly 5-lobed, laxly scaly and hairy. Corolla 60–70 x 25–30mm, trumpet-shaped, pure white, scented; tube 50–60 x 4–5 x 8–10mm, slightly curved, a little lobed at the base, sparsely scaly outside, densely hairy in the proximal ½ and glabrous distally inside; lobes 10–13 x 7–12mm, spreading, broadly obovate to sub-circular, glabrous. Stamens exserted to 10mm; filaments linear, hairy in the proximal ½, glabrous distally; anthers 2–2.3 x c.1mm, oblong, base obtuse. Disc low, glabrous. Ovary 6–7 x c.1.5mm, cylindrical, gradually narrowed distally, densely covered with sub-patent white or greyish hairs, and some obscure scales; style c.60mm, patently hairy and scaly for over ½ its length, becoming scaly only, glabrous for the distal 6–10mm; stigma exserted to 10mm, conical-globose, crenulate. Fruit (immature) to 30 x 5mm, fusiform, often curved.

Habitat: In open evergreen forest, margins of valley forest, on moss-covered ground among non-calcareous rocks in shade.

Distribution: Papua New Guinea, Maneau Range: Mt Maneao, Mt Yauama and Mt Simpson. Central Province: Mt Albert Edward. Eastern Highlands District: Mt Gahavisuka.

Altitude: 1860-2600m

Notes

Named after the collector, the Reverend Canon Norman Cruttwell, for most of his life a missionary in Papua New Guinea but also a keen botanist who collected many vireyas.

Nomenclature

Type: Cruttwell 525, 11 June 1954. New Guinea (SE), North-eastern District, Mt Maneao, 2590m (K, E).

Flags

Occurs in Countries: PG Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Vireya Habit: Tree Fl. Colour: white

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:180

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Rhododendron cuffeanum [Craib ex] Hutchinson

Shrub of uncertain height. Stem swollen and tuber-like at the base. Young growth lepidote. Leaves rather narrowly elliptic, acuminate at apex 100-125 x 30-40 mm, upper surface brownish green, sparsely lepidote, lower surface pale green, lepidote with distant, golden scales; petiole iepidote and with a few sparse loriform setae. Inflorescence c. 5-flowered, pedicels lepidote and sparsely pubescent. Calyx unequally 5-lobed, the longest lobe c. 7 mm, all oblong-ovate, foliaceous, lepidote and sparsely pubescent outside, fringed with loriform setae. Corolla funnel-campanulate, white with a yellow blotch inside, 55-65 mm, the tube 22-35 mm, pubescent outside at the base, sparsely lepidote all over, tube glabrous inside. Stamens 10, filaments pubescent towards the base. Ovary densely lepidote, style impressed, lepidote in the lower half, pubescent near the base. Capsule unknown.

Distribution: Known only in cultivation

Illustrations:

Notes

This is an obscure species in many ways. There is no herbarium material from the wild and it is known only from cultivated material. Young plants were reputedly collected by Lady Cuffe on Mt Victoria in Burma and grown on at Glasnevin, Dublin. The notes with the type description in the Botanical Magazine suggest that the place of origin was Sindaung on the edge of the Shan plateau, but this was later altered to Mt Victoria by Hutchinson. The swollen stem base, which is illustrated in the Botanical Magazine plate appears to be unique in this group of rhododendrons. Hutchinson's two descriptions (Bot. Mag.y cited above, and Notes R.B.G. Edinb. 12:52, 1919) do not agree entirely with material at Edinburgh said to come from the type plant and determined by him: for instance, in this material the corolla is sparsely lepidote all over, not 'not lepidote except towards the 5 lobes which are sparingly so towards the middle'; and thestyle is pubescent and lepidote at the base, not just lepidote. I have not been able to trace a type specimen, so this matter cannot be resolved.

Flags

Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: white, yellow

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):45

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Rhododendron culminicola F.Muell.

Notes

Latin – culmen – summit; cola – inhabiting. Summit-dwelling.

Nomenclature

Type: MacGregor s.n., 1889. New Guinea (E), Mt Victoria (MEL).

Synonymy: R. culminicolum F.Muell., Trans. R. Soc. Vict. n.s. 1889. 1(2): 23 (orthographic variant). R. nodosum C.H.Wright, Kew Bull. 1899. 103. R. keysseri Foerster, Fedde Rep. 1914. 13: 223. R. angiense J.J.Sm. in Gibbs, Phyto. Fl. Arfak Mts, 1917. 169, non J.J.Sm. (1914). R. convexum Sleumer, Reinwardtia 1960. 5: 218. R. gregarium Sleumer, Reinwardtia 1960. 5: 221.

Flags

Occurs in Countries: ID, PG Altitude Ranges: 0 - 1,000m: 1,000 - 2,000m: 2,000 - 3,000m: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Vireya Habit: Tree Fl. Colour: pink, purple, red

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:308

Rhododendron culminicola var. angiense (J.J.Sm.) Sleumer

Differs from var. culminicola in having smaller more rounded scales, corollas 25–35mm and smaller fruits, 4–5mm in diameter.

Habitat: In disturbed Nothofagus/Tristania forest or forest margins and open summit areas, locally common, but often sterile, mostly terrestrial.

Distribution: Indonesia, New Guinea (W), Vogelkop Peninsula, Arfak, Nettoti and Tohkiri Mts. Papua New Guinea, Star Mts, Tel Basin.

Altitude: 900-2300m

Notes

Named after the lakes where the type specimen originated.

Nomenclature

Type: Gjellerup 1217. New Guinea (W), Arfak Mts, Anggi Lakes, 1900m (BO, L).

Rhododendron culminicola var. culminicola

Shrub or tree to 8m. Twigs 2–5mm in diameter, scaly but early glabrescent; internodes 2–10cm. Leaves 3–7 together in tight pseudowhorls. Blade 25–80 x 1–45mm, elliptic, broadly elliptic, obovate or more rarely ovate; apex obtuse to rounded, sometimes abruptly sub-acuminate; margin revolute; base broadly tapering, rounded to sub-cordate; at first densely covered on both sides with flattish, pale scales, glabrescent above at maturity, laxly scaly beneath. Scales small, flat, shallowly and irregularly lobed with a broad flange and small slightly impressed centre. Mid-vein narrowly impressed above, broadened, wrinkled, and prominent in the proximal part; lateral veins 4–8 per side, curved-spreading and indistinctly anastomosing before the margin, slightly impressed above, somewhat raised beneath, reticulation sub-dense, obscure above, slightly raised beneath. Petiole 2–9 x 1–3mm, grooved above, scaly. Flower buds to 25 x 15mm, ovoid or broadly ovoid, smooth with all bracts appressed. Outer bracts sub-circular to ovate, sometimes with a short narrow point, inner ones ovate to obovate, laxly scaly and sometimes hairy at the base outside, glabrous or laxly to sub-densely hairy inside. Bracteoles filiform to linear, glabrous, to 20 x 3mm. Inflorescence 4–9 flowers in an open umbel, curving downwards. Pedicels 15–24 x c.1mm, laxly to sub-densely scaly, sometimes also hairy. Calyx obliquely disc-shaped, wavy, obtusely and shortly lobed, c.4mm in diameter, scaly outside, occasionally fringed with hairs. Corolla 35–45 x 12–25mm, obliquely tubular, red to purple, sometimes pink; tube 25–40 x 4–6 x 8–15mm, distinctly curved, laxly to sub-densely scaly outside, sparsely to sub-densely hairy in the lower part of the tube inside; lobes 8–18 x 8–15mm, broadly obovate to sub-circular, sub-erect or spreading, overlapping 1⁄3–2⁄3. Stamens sub-equal, not or only weakly exserted; filaments linear, laxly to sub-densely hairy in the lower ½, glabrous distally; anthers 2–3.5 x 1–1.5mm, obovate to broadly oblong, base often minutely apiculate. Disc prominent, shortly hairy at the upper margin. Ovary 5–7 x 2–3mm, sub-cylindrical, white or yellowish hairy, and densely (but obscurely) scaly, gradually tapering distally; style slender, mostly with some sparse hairs and scales at the base, rarely so up to the proximal 1⁄3, becoming exserted; stigma round. Fruit 25–40 x 6–8mm, sub-cylindrical, tapering at both ends, scaly and laxly hairy.

Habitat: Low mossy forest or the margins of sub-alpine shrubberies, open slopes or summit vegetation, also found in alpine pasture, in both primary and secondary communities, often as part of the forest undergrowth, locally plentiful.

Distribution: Indonesia and Papua New Guinea. Widespread on the island of New Guinea on the Main Range, from Mt Jaya (Carstensz) to the Southern and Western Highlands and in the Owen Stanley Range, also in the Mt Saruwaged–Rawlinson Range area.

Altitude: 2400-4000m

Notes

Rhododendron culminicola is conceived here in the broad sense of Sleumer (1966) with the exception that the variety nubicola has been reinstated as a good species. Specimens from the upper montane forest (at the lower elevations from c.2400m) tend to have larger flowers and tapering leaf bases. Forms at higher elevations (3200–4000m) have smaller flowers and smaller, stiffer, short-petioled or sub-sessile leaves with rounded or sub-cordate bases. It is one of the small number of variable species which are distributed all over the mountainous part of New Guinea.

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Rhododendron cumberlandense E. L. Braun

Shrub or small tree to 2m tall, usually rhizomatous; young twigs reddish brown, sparsely to densely covered with unicellular hairs and multicellular eglandular hairs, rarely glabrous or with only multicellular eglandular hairs. Vegetative bud scales glabrous abaxially; margin unicellular-ciliate. Leaf blade membranaceous, ovate or obovate to elliptic, (3.1-)4.6-7.0(-8.1) x (1.3-)1.8-2.9(-3.5)cm; base acute to oblique; apex acute to obtuse, often mucronate; adaxial surface glabrous, occasionally with sparse multicellular eglandular hairs, the midvein densely covered with unicellular hairs; abaxial surface glabrous, or very sparsely covered with multicellular eglandular hairs usually also glaucous, the midrib sparsely to densely covered with unicellular hairs and multicellular eglandular hairs, rarely with only multicellular eglandular hairs; margin entire, ciliate with multicellular eglandular hairs; petiole (0.2-)0.3-0.5cm long, sparsely to densely covered with unicellular hairs and multicellular eglandular hairs, rarely with only unicellular hairs. Flower bud scales chestnut brown; abaxial surface glabrous; margin ciliate at the apex and glandular below, rarely glandular to the apex. Flowers appearing after the leaves have expanded; inflorescence a shortened raceme of 3 to 7 flowers. Pedicels (0.4-)0.5-0.7(-Q.9)cm long, sparsely to densely covered with unicellular hairs and multicellular eglandular hairs, rarely with multicellular gland-tipped hairs and then the sepals eglandular. Sepals less than 0.1-0.2(-0.3)cm long, often varying in length on the same flower; margins setose with multicellular eglandular hairs, rarely with multicellular gland-tipped hairs and then the pedicels eglandular; abaxial surface sparsely to densely covered with unicellular hairs and multicellular eglandular hairs, rarely with only multicellular eglandular hairs. Corolla red, fragrance acrid, the tube longer than the limb and abruptly expanding into it; upper corolla lobe 1.3ó1.8(ó2.1) x l.l-1.6(-2.0)cm; lateral lobes 1.4-1.9(-2.5) x 0.7-1,2cm; corolla tube (1.4-)1.6-2.1(-2.4)cm long, 0.2-0.3cm wide at base; outer surface of corolla densely covered with unicellular hairs and sparsely covered with multicellular gland-tipped hairs that continue up the corolla lobes; inner surface of corolla densely covered with unicellular hairs. Stamens (4.2-)4.9-6. l(-6.2)cm long, with dense terete or flattened unicellular hairs on proximal (1.7-)2.3-3.0(-3.1)cm of filament, exserted (2.7-)3.1-4.1(-4.3)cm beyond throat of corolla. Style (3.9-)4.5-6.5(-7.2)cm long, exserted (2.8-)3.0-4.9(-5.5)cm beyond throat of corolla, densely covered with unicellular hairs on proximal 0.1-1.7(-2.8)cm; stigma 0. l-0.2cm wide. Ovary 0.2-0.3(-0.4)cm long, 0. l-0.2cm wide at the base, densely covered with multicellular eglandular hairs over dense unicellular hairs, nectary with a crown of dense unicellular hairs. Capsules (1.2-) 1.4-2.3(-2.8) x 0.5-0.7(-0.8)cm, ovate to broadly ovate, sparsely to moderately covered with unicellular hairs and sparsely to densely covered with multicellular eglandular hairs. Seeds pale to dark chestnut brown, ovate or elliptic to fusiform, (1.8-)2.1-3.4 (-4.5) x (0.5-)0.7-l.l(-1.4)mm, body (0.8-)l.l-1.6(-1.9) x (0.2-)0.4-0.6(-0.8)mm; testa expanded and dorsiventrally flattened, surrounding the body, the cells short, end-walls transverse.

Habitat: Ridge-tops above 900m, but also occasionally at lower elevations, in mixed mesophytic forests.

Distribution: Western most Virginia and eastern Kentucky in the Cumberland Mountains and Plateau, south through Tennessee to northern Alabama, and east of the Tennessee River Valley in the southern Blue Ridge, along the border of Tennessee and North Carolina, south to northern Georgia. Isolated populations occur in Talladega, Cleburne and Randolph counties in Alabama

Altitude: Around 900m

Illustrations:

Notes

The name R. bakeri (Lemmon, 1938) has been used for this diploid flame azalea since Skinner (1955) considered R. bakeri to be the same taxon as R. cumberiandense. Since R. bakeri, was an earlier name, it was properly used over R. cumberiandense. However, the type specimen of Azalea bakeri (= R. bakeri) is not at all similar to the type of R. cumberiandense. The specimen, which is labelled Azalea bakeri by Lemmon, has young expanding leaves, which are densely pubescent on the abaxial surface. In addition, the margins of the floral bud scales are all unicellular-ciliate, and the corolla possesses both glandular and eglandular multicellular hairs. None of the above characters is found in R. cumberiandense, which flowers well after the leaves have expanded and usually has glabrous leaves (never densely pubescent). In addition, the floral bud-scale margins and the outer surface of the corolla are consistently glandular in R. cumberiandense. Therefore Lemmon's specimen is probably a hybrid between R.flammeum and R. canescens (see hybrid names, p. 362). Thus, the correct name for the diploid flame azalea is Rhododendron cumberiandense.

Chromosome number: 2n = 26 (Li, 1957; WEEngham, 1973).

Rhododendron cumberiandense is most closely related to R. calendulaceum (see Phylogenetic Analysis) and can be distinguished from the latter by its flowering well after the leaves have expanded, and by the eglandular condition of the pedicel and sepal margins. In addition, the leaves are very glaucous abaxially, and often are bluish green to dark olive-green in colour, especiaMy upon drying. This species is primarily restricted to the Cumberland Mountains and Plateau, where it is morphologically and phenologically distinct from R. calendulaceum. In the southern Blue Ridge, however, R. cumberiandense can hybridize with R. arborescens or R. viscosum. It can also occupy the same kinds of habitats as high-altitude late-flowering individuals of R. calendulaceum. In these areas it is more difficult to distinguish R. cumberiandense from R. calendulaceum (see discussion under R. calendulaceum). See Appendix for citation of representative hybrid specimens.

Nomenclature

Synonymy: Azalea cumberlandense (E. L. Braun) Copeland, Am. Midi. Nat. 30: 533-625 (1943). Type: Kentucky, McCreary Co.: Yahoo Ridge, 15 vi 1935, E. L. Braun 971 (holo. Herb. Braun, n.v.; iso. A).

Flags

Altitude Ranges: 0 - 1,000m Subgenus: Pentanthera Habit: Tree

Kron, K.A. (1993) A Revision of Rhododendron Section Pentanthera. Edinburgh Journal of Botany 50(3):309

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Rhododendron cuneatum W. W. Smith

Shrub, l-2(-4) m. Leaves densely lepidote, 11-70 x 5-26 mm, narrowly to broadly elliptic, apex acute, obtuse or rounded, strongly mucronate, base cuneate, undersurface uniformly fawn to deep rust or occasionally with darker spots, the scales contiguous or overlapping. Inflorescence up to 6-flowered, pedicels 2-13 mm, lepidote. Calyx (2-)5-8(-12) mm, lobes usually oblong, apex rounded to acute, with pale scales forming a central band, margin long-ciliate, sometimes with a few scales. Corolla deep purple to rose-lavender, often with darker markings, rarely almost white, funnel-shaped, (12-)22-31 mm, tube (5-)10-16 rmn, pubescent within and often ouside also, lepidote or elepidote outside. Stamens 10, pubescent in the lower part, varying in length. Ovary lepidote, style declinate, longer than or rarely equal to stamens, pubescent towards the base. Capsule lepidote, ovoid, up to 14 mm

Distribution: China (N & W Yunnan, SW Sichuan)

Notes

A distinctive species, in many ways similar to the species of subsection Heliolepida (p. 87), from which it differs mainly in the possession of a large, deeply Iobed calyx. It is in many ways (large, zygomorphic flower, type of scaling, etc.) aberrant in subsection Lapponica, and stands in an intermediate position between Lapponica and Heliolepida. The Philipsons (1975, p. 16) note the occurrence of natural hybrids with R. hippophaeoides and other, undetermined, species.

Nomenclature

Type: China, Yunnan, eastern flank of Lichiang range, 3650 m, x 1910, Forrest 6738 (holo. E)

Synonymy: R. ravum Balfour f. & W. W. Smith, Notes R.B.G. Edinb. 9:270 (1916). Type: China, Yunnan, mts. in NE of the Yangtze bend, 11000 ft, vii 1913, Forrest 10423 (holo. E). R. cinereum Balfour f. in Millais, Rhododendrons 145 (1917) nom. nud. R. cheilanthum Balfour f. & Forrest, Notes R.B.G. Edinb. 11:32 (1919). Type: China, Yunnan, mts in NE of Yangtze bend, 10-11000 ft, vii 1913, Forrest 11736 (holo. E). R. sclerocladum Balfour f. & Forrest, op. cit. 11:133 (1919). Type: China, Yunnan, mts of Chungtien plateau, 11000 ft, vii 1914, Forrest 12665 (holo. E)

Flags

Occurs in Countries: CN Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: purple, rose, white

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):95

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Rhododendron cuneifolium Stapf

Notes

Latin – cuneus – a wedge; folium – leaf. Alluding to the wedge-shaped leaf base.

Nomenclature

Type: Haviland 1180. North Borneo, Mt Kinabalu, 1650–2745m (K, SAR).

Synonymy: R. quadrasianum S.Vidal var. cuneifolium (Stapf) H.F.Copel., Phil. J. Sc. 1929. 40: 145.

Flags

Occurs in Countries: MY Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Vireya

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:47

Rhododendron cuneifolium var. cuneifolium

Shrub to 2m. Twigs smooth apart from some raised leaf scars, red or green passing to brown, minutely shortly hairy and sparsely scaly. Leaves spirally arranged, or only weakly grouped into loose pseudowhorls. Blade 10–30 x 3–7mm, narrowly obovate to spathulate; apex retuse to rounded; margin entire or sometimes crenulate in the distal ½; base tapering, laxly silvery scaly becoming glabrescent above, laxly and more persistently impressed scaly beneath. Scales circular with a moderately broad flange which is often marked with radial furrows and a broad centre. Mid-vein deeply impressed above and raised below but obscure in high altitude forms; lateral veins obscure, rarely 1 or 2 per side. Petiole 2 x 1mm, without a conspicu­ous groove, sparsely scaly and often very finely hairy. Flower buds c.6 x 3mm, ellipsoid, brown, with a few scales outside distally and a broad fringe of white hairs. Bracts ovoid. Inflorescence of mostly solitary flowers, occasionally up to 3-flowered, flowers half-hanging, occasionally horizontal or vertically hanging. Pedicels c.5 x 1mm, green with white scales but no hairs. Calyx of 5 equal ovate-triangular lobes to 1.5mm or sometimes with 2 longer lobes to 2mm. Corolla 15–20 x c.8mm, pale red to orange-red, without scent, sub-cylindrical or narrowly funnel-shaped; tube c.15 x 6 x 7mm, densely scaly outside, glabrous inside; lobes c.5 x 4mm, semi-erect to spreading, overlapping ½–2⁄3, scaly outside except near the margin. Stamens in a loose cluster on the lower side of the mouth, exserted to 8mm; filaments c.18mm, pale pink, glabrous, tapering from just above the base; anthers c.1 x 0.75mm, dark brown. Ovary c.2.5 x 2mm, green, densely covered with silvery scales but no hairs; style 16–20 x c.1mm, glabrous apart from a few scales at the base, pale yellow, lying on the lower side of the corolla but curving upwards; stigma circular. Fruit 7–11 x 4–5mm, the valves curving back on opening. Seeds c.1.9mm, without tails 0.7mm, the longest tail 0.6mm.

Habitat: Mostly terrestrial, sometimes epiphytic. Common on Mt Kinabalu from 1500 to 2800m, where it occupies a zone between that of R. borneense and R. ericoides.

Distribution: Malaysia (Borneo), Sabah, Mt Kinabalu and Mt Alab. Reported from Sulawesi but this has not been properly substantiated (Monod de Froideville 187 from Makale, Makale-Bi(n)tuang, Rante Karua, (Rantepao), SW Central Sulawesi, 1200m).

Altitude: 1500-2800m

Notes

Flowers Jan.–Dec. but apparently not continuously, having rest periods between flushes of flowers.

Rhododendron cuneifolium var. microcarpum Argent, A.Lamb & Phillipps

Differing from the type mainly in the following. Twigs prominently grooved with leaf supports and covered in scales but without hairs. Blade 5–8 x 1.5–2.5mm, narrowly obovate; lateral veins always obscure. Ovary 1.5–2 x 1.5–2mm. Fruit 4–4.5 x 3mm. Seeds 0.8–0.9mm, without tails 0.4mm, the longest tail 0.3mm.

Notes

Greek – micro – little or small; carpus – fruit. Alluding to the very small fruit of this variety.

An extreme form of R. cuneifolium known only from Mt Trus Madi, Sabah, E Malaysia.

Nomenclature

Type: Collenette 646b, 7 Jan. 1961. Sabah, Mt Trus Madi, Crest of main ridge, 2300m (K).

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Rhododendron curviflorum J.J.Sm.

Shrub to 2.5m. Twigs semi-rounded, 2.5–4mm in diameter, tips sub-densely sub-stellately scaly, older parts glabrescent; internodes 4–17cm. Leaves 4–7 together in tight pseudowhorls. Blade 100–130 x 50–70mm, ovate to ovate-elliptic; apex shortly apiculate, broadly acute; margin entire or slightly sinuate, flat or weakly recurved; base rounded or occasionally broadly tapering, dark green and glabrescent above, sub-densely brown-scaly beneath. Scales dense, small, irregularly and deeply stellate; centre dark brown, finally blackish, faintly impressed but with occasional long-stalked scales from the flat surface. Mid-vein narrowly impressed above, strongly raised below; lateral veins 5–8 per side, spreading at a wide angle, straight below, curved upwards and anastomosing, slightly impressed above, prominent beneath, reticulation dense, faintly impressed or raised above, much more distinct and prominent beneath at least when dry. Petiole 7–17 x 2–3mm, grooved above, densely brown scaly but becoming glabrescent. Flower buds to 40 x 25mm, ovate, smooth with all the bracts appressed, dull pale green except for brown marks at the apices of the bracts, minutely hairy outside and with areas of small brown scales towards the bract apices. Outermost bracts broadly ovate and apiculate; central bracts to 20mm, hemispherical to broadly ovate, shortly emarginate, minutely hairy outside, scaly distally near the apex and fringed with small brown scales, glabrous inside; innermost bracts spathulate. Bracteoles 36 x c.1mm, linear becoming slightly broadened towards the apex, white hairy throughout and with slender, brown, long-stalked scales near the apex. Inflorescence an open 5–11-flowered umbel, the flowers mostly horizontal but the mouth facing downwards due to the curvature of the tube. Pedicels 20–35 x 2–3mm, densely shortly hairy, without scales, except for a few distally just under the calyx. Calyx 4–6mm in diameter, disc-shaped, patently white hairy outside but fringed on the margin with scales, the lobes c.1mm, shortly triangular, obtuse. Corolla 60–65 x 40–50mm, tubular, oblique, unequally 5-lobed, yellow (or mauve; see note below), without scent; tube 35–40 x 9–11 x 11–17mm, cylindrical but sulcate and 5-angled in the proximal ½, slightly compressed laterally in the upper ½, densely shortly patent hairy outside and without scales, hairy in the lower ½ of the tube inside; lobes 22–25 x 18–20mm, hairy outside except near the margins, all lobes spreading to the horizontal, the three upper lobes overlapping to halfway, the two lower lobes not overlapping. Stamens clustered on the upper side of the mouth, exserted to c.12mm; filaments linear, densely to sparsely patently hairy below, more slender and glabrous towards the top; anthers c.4 x 1.8–2mm, brown, broadly oblong, the base obtuse. Disc prominent, deeply lobed, densely hairy above, less so below. Ovary 6–7 x 4–5mm, elongate-conical, tapering distally, densely hairy with slightly forward-pointing white hairs; style deep within the tube on the flower opening, becoming exserted to 15mm, green, densely patently hairy nearly to the top; stigma thick, lobed, reddish-brown. Fruit 40–50 x 6–7mm, fusiform, often curved and longitudinally grooved. Seeds 60–70mm, without tails c.1mm, the longest tail 3.8mm.

Habitat: Epiphytic or terrestrial in secondary forest or landslips.

Distribution: Indonesia, New Guinea (W), Keyts Mts and Bele R. around Pabililo and the Ibele valley, near Wamena.

Altitude: 1900-2700m

Notes

Latin – curvi – curved; florum – with flowers. Alluding to the curved flowers.

Sleumer (1966) notes: ‘The size of the corolla in Smith’s description of 1914 differs from that in t.36 B; unfortunately, the type material, conserved in formaline at Bogor, is practically useless. I have drawn a new description of it based on good and apparently conspecific specimens (BRASS 11215 AND 11536) from the Bele R., which have yellow flowers instead of “lilac” as said of the type mater­ial, which came from the Keyts Mts. Also the description of the perulae [bracts], not given in the original diagnosis, is made after the BRASS collections’. I have followed Sleumer’s interpretation of this species; the anatomical characters certainly agree closely with Smith’s descriptions but I cannot find the discrepancy in measurements that he mentions. Rhododendron curviflorum was common around the village of Pabilio above Wamena and was all very uniform yellow in colour. It would be odd for this species to occur in the lilac mentioned in the original type description. This may have been an error in the field descriptions or we may still be dealing with two different species. Further collecting in the Keyts Mts will need to be done to resolve this.

Nomenclature

Type: Cocq d’Armandville 233, Dec. 1912. New Guinea (SW), Johannes Keyts Mts (BOG†). Neotype: Brass 11215. New Guinea (W), Bele R., c.18km NE of Lake Habbema (L).

Flags

Occurs in Countries: ID Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Vireya Habit: Epiphyte, Non-Tree Fl. Colour: mauve, yellow

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:303

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Rhododendron cuspidellum Sleumer

Terrestrial shrub to 1.5m. Twigs 3–6mm in diameter, rounded, scaly becoming glabrescent; internodes 8–17cm. Leaves 4–7 together in tight pseudowhorls of very variably sized leaves at the same node. Blade 70–200 x 20–70mm, narrowly ovate or elliptic; apex acuminate, with long sub-caudate points, acute; margin entire, very narrowly slightly revolute; base broadly tapering, rounded to sub-cordate; glabrescent above, laxly and more persistently scaly beneath. Scales small, marginal zone irregularly sub-stellately lobed; centre darker and slightly impressed. Mid-vein narrowly impressed above, strongly raised below, becoming gradually more slender from base to apex; lateral veins 8–10 per side, wide-spreading, straight below, indistinctly curved-anastomosing before the margin, faintly raised on both sides, sometimes inconspicuous especially beneath. Petiole 3–6 x 2–3mm, grooved above, scaly. Flower buds 35 x 25mm, sub-orbicular-ovoid. Bracts to 35 x 23mm; outer bracts ovate, apex very shortly subulate, the inner ones larger, ovate, obtuse, innermost ones spathulate, all laxly sub-stellately scaly and very shortly hairy outside and along the margin. Bracteoles to 30 x 4mm, linear to linear-sub-spathulate, shortly hairy. Inflor­escence a 9–12-flowered complete umbel. Pedicels 25–60 x c.1mm, laxly scaly, without hairs. Calyx c.3mm in diam­eter, disc-shaped, wavy and obscurely lobed, densely scaly outside. Corolla 35–45 x c.35mm, tubular-funnel-shaped, orange or orange-yellow; tube 15–20 x 5–6 x 15–17mm, straight, 5-angular, lobed at the base, sub-densely to laxly sub-stellately scaly outside, sparsely or very sparsely hairy proximally inside; lobes 23–27 x 15–22mm, broadly obovate-spathulate or sub-circular. Stamens c.25mm, sub-equal, slightly exserted; filaments linear and densely patently hairy in the proximal ½, glabrous distally; anthers c.4 x 1mm, oblong. Disc hairy. Ovary 5–6 x c.2.5mm, cylindrical-conical, white-hairy and scaly, abruptly contracted distally; style nearly equalling the stamens, hairy and distinctly scaly in the proximal 1⁄3–2⁄3; stigma deeply 5-lobed.

Habitat: Secondary forest, locally common.

Distribution: Indonesia, New Guinea (W), Wissel Lakes region; Armina, Sjuga-Wagura area, Babo District.

Altitude: 150-1900m

Notes

Latin – cuspis – a sharp rigid point; ellum – diminutive. The leaves being sharply pointed.

Very similar to R. baenitzianum but said to differ by the smaller flowers; more collections are badly needed to evaluate this.

Nomenclature

Type: Versteeg BW 3008, 20 March 1959. New Guinea (W), Wissel Lakes, Enarotali, 1900m (L, E).

Flags

Occurs in Countries: ID Altitude Ranges: 0 - 1,000m: 1,000 - 2,000m Subgenus: Vireya Habit: Non-Tree

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:319

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Rhododendron cyanocarpum (Franchet) W. W. Smith

Shrub or small tree, l-3.8m; bark rough; young shoots glabrous. Leaves broadly elliptic to orbicular, 6.5-12.5 x 4.2-9cm, 1.2-1.6 x as long as broad, apex and base rounded, upper surface glabrous, lower surface ± glaucous with epidermis mammillate, glabrous or with a few scattered hairs on the midrib towards the base; petioles 1 -3cm, often shghtly winged, glabrous. Inflorescence 6-11-flowered; rhachis 5-10mm; pedicels 10-20mm, glabrous. Calyx (2-)7-15mm, cupular, greenish, glabrous, lobes truncate. Corolla ± campanulate to funnel-campanulate, white or cream to clear pink, with dark nectar pouches, flecks lacking, (40—)50—60mm. Ovary glabrous or rarely with a few glands, style glabrous. Capsule 15-20 x 8-10mm, usually with a glaucous bloom.

Habitat: Open pasture, forest margins

Distribution: China (W Yunnan)

Altitude: 3000-4000m

Notes

Superficially close to R. thomsonii but differing in the paler flowers and the mammillate leaf epidermis. Var. eriphyllum, which is only known from the type and differs only it its sparsely glandular ovary, is not worthy of formal recognition.

Nomenclature

Type: China, Yunnan, rochers de Tsang-chan, Delavay 3947, 4166 (K). R. hedythamnum Balfour f. & Forrest var. eglandulosum Handel-Mazzetti, Akad. Wiss. Wien Math.-Naturwiss. Kl., Anz. 19: 3 (1923). Type: China, Yunnan, orient, montis Dsang-schan, prope Dali, 3900-4050m, 13 v 1910, Handel-Mazzetti 8712, n.v. R. cyanocarpum (Franchet) W. W. Smith var. eriphyttum [Balfour f. & W. W. Smith ex] Tagg in Stevenson (ed.), The Species of Rhododendron 738 (1930). Type: China, Yunnan, western flank of the Tali Range, 11000ft, vii 1913, Forrest 11593 (holo. E; iso K)

Synonymy: R. thomsonii Hooker f. var. cyanocarpum Franchet, J. Bot. (Morot) 9: 389 (1895)

Flags

Occurs in Countries: CN Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Tree Fl. Colour: cream, pink, white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):423

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Rhododendron cyrtophyllum Wernham

Shrub. Twigs thick, c.2mm in diameter, rounded, the tips densely covered with sessile or very shortly stalked roundish scales, lower parts glabrescent, becoming smooth; internodes 2–4cm. Leaves 3–5 together in loose pseudowhorls at the upper nodes, sometimes spiral. Blade 25–32 x 12–19mm, elliptic or ovate-elliptic; apex gradually tapering, obtuse, apiculate; margin strongly revolute in the distal 2⁄3, hardly at all proximally; base rounded or sub-truncate, sub-densely to laxly scaly on both sides initially, slowly glabrescent above, persistently scaly beneath. Scales round, entire, marginal zone narrow; centre thick, little or not impressed. Mid-vein slightly impressed above, very prominent beneath; lateral veins 5–6 per side, irregular, spreading, a little raised above, more distinctly so beneath, reticulation obscure. Petiole 2–3 x c.0.8mm, thick, scaly. Bracts to 10 x 6mm, ovate, obtuse, glabrous except for some scales near the top outside, shortly patently hairy inside. Inflorescence a 5–8-flowered umbel. Pedicels 7–12mm, slender, scaly. Calyx oblique, obscurely 5-lobed, c.2.5mm in diameter. Corolla c.35mm, pinkish-red, tubular below, dilated upwards; tube 25–30 x 4 x 7–10mm, very densely scaly outside, glabrous inside, curved; lobes c.8mm, spreading, rounded. Stamens c.25mm; filaments linear, sparsely hairy proximally, glabrous upwards; anthers 2.5mm, broadly oblong. Disc glabrous. Ovary c.5 x 2mm, densely scaly and laxly patently short-hairy; abruptly contracted distally; style 20mm, glabrous.

Distribution: Indonesia, New Guinea (W), Mt Jaya (Carstensz), along the Utakwa R.

Altitude: 2520-3050m

Notes

Greek – kryptos – hidden; phyllon – leaf. A somewhat obscure allusion!

Not yet recollected and remaining poorly known. Very distinctive in the unusual feature of the leaves being more revolute distally than proximally which is the reverse of the usual situation.

Nomenclature

Type: Kloss s.n. New Guinea (S), Mt Carstensz (BM).

Flags

Occurs in Countries: ID Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Vireya Habit: Non-Tree

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:60

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Rhododendron daiyumcum P.X.Tan

Shrub; young shoots becoming glabrous. Leaves coriaceous, oblong-lanceolate, 2.8-3.8 x 1.3-1.7cm, apex slightly acute, upper surface greenish, opaquely brown when dry, lower surface paler below, covered with thin lanate indumentum, with the midrib setulose; petioles 3-4mm, densely brownish, strigose with some longer setose hairs. Inflorescence 1-flowered; pedicels 6-8mm, densely strigose. Calyx densely brown-strigose, lobes crenulatc, 5mm. Corolla obliquely funnel-campanulate, rose, c.25mm, lobes 20-22mm, obovate-oblong. Stamens 10, filaments puberulent. Style glabrous. Fruit not known.

Distribution: China (Fujian)

Notes

Known only from the type. Allied to R. farrerae but differing in several distinctive characters.

Nomenclature

Type: China, Fujian, Dehua Xian, prope Catervam Daiyuan, 20 iv 1975, L.K. Ling 3040 (holo. Fujian Normal Univ.)

Synonymy: R. daiyuenshanicum P.X.Tan, Survey Gen. Rhododendron S. China 96, f.22, 3 (1983). Type as above.

Flags

Occurs in Countries: CN Subgenus: Tsutsusi Habit: Non-Tree Fl. Colour: rose

Chamberlain, D.F. & Rae, S.J. (1990) A Revision of Rhododendron IV Subgenus Tsutsusi. Edinburgh Journal of Botany 47(2):145

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Rhododendron dalhousiae Hooker

Epiphytic or more rarely free-growing shrub. Young shoots loriform-setose. Leaves mostly narrowly elliptic, more rarely tending to obovate, (75-)100-170 x 35-70 mm, tapered to the base and to the ± rounded apex, petioles variably loriform-ciliate, lower surface greyish or brownish green with small, slightly unequal, reddish scales more than their own diameter apart; margins often crenulate. Inflorescence 2-3-flowered, pedicels 15-20 mm, lepidote and pubescent, accrescent in fruit. Calyx conspicuous, deeply 5-lobed, the lobes oblong or oblong-triangular, rounded at the apex, 10-15 x 5-10 mm, lepidote at the base, the middles of the lobes with few to many filiform-acicular hairs. Corolla narrowly funnel-campanulate to funnel-campanulate, white or cream, often yellowish inside, sometimes with 5 red lines running from the base of the tube to the apices of the lobes, 85-105 mm, tube 60-75 mm, very sparsely lepidote to elepidote outside. Stamens 10, filaments pubescent in the lower part. Ovary lepidote, tapered into the style which is lepidote in the lower part. Capsule cylindric-fusiform, 40-50 x 15-20 mm, lepidote, rather strongly 5-ridged.

Flags

Occurs in Countries: BT, CN, IN, NP Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: cream, red, white, yellow

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):37

Rhododendron dalhousiae var. dalhousiae

Corolla without 5 longitudinal red lines

Habitat: Epiphytic on trees, or on rocks and cliffs in forest and scrub

Distribution: Nepal, India (Sikkim, W Bengal), Bhutan, China (S Xizang)

Altitude: 1800-2450m

Illustrations:

  • The Garden 28: opp. p. 318 (1885)
  • Flora & Sylva 3:40 (1905)
  • Bot. Mag. 79: t. 4718 (1853)
  • Rhodo. lmmerg. Laubg. Jahrb. 1968:56.
Nomenclature

Type: Sikkim Himalaya, 7000-9000 ft, Hooker (holo. K)

Rhododendron dalhousiae var. rhabdotum (Balfour f. & Cooper) Cullen

Corolla with 5 longitudinal red lines

Habitat: Epiphytic in forests or free-growing on hillsides

Distribution: India (Arunachal Pradesh), China (S Xizang)

Altitude: 1500-2600m

Illustrations:

  • Gard. Chron. 90:235 (1931)
  • Gard. Chron. 96: 34 (1934)
  • Bot. Mag. 159: t. 9447 (1936)
Notes

The red-striped flower is the only distinguishing feature of var. rhabdotum.

Nomenclature

Synonymy: R. rhabdotum Balfour f. & Cooper, Notes R.B.G. Edinb. 10:141 (1917). Type: Bhutan, Punakka, 8000 ft, 29 v 1915, Cooper 3987 (holo. E)

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Rhododendron dasycladoides Handel-Mazzetti

Shrub or small tree, 2-5m; young shoots densely glandular-setose. Leaves ovate to obovate, 4.5-9 x 2.9-4cm, 2-3.5 x as long as broad, apex rounded, apiculate, base rounded, margin glandular-ciliate at base, upper surface glabrous when mature or with traces of hairs at base, lower surface with lamina glabrous and midrib glandular-setose; petioles 1-1.5cm, glandular-setose and floccose-tomentose. Inflorescence 5-8-fIowered; rhachis c.2mm; pedicels c.l5mm, tomentose and stipitate-glandular. Calyx 2-7mm, stipitate-glandular, lobes rounded. Corolla funnel-shaped, pale to deep purplish rose, with darker flecks, 35-40mm. Ovary dendroid-tomentose; style glabrous. Capsule up to 30 X 5mm, curved.

Habitat: Forests, etc.

Distribution: China (SW Sichuan, adjacent NW Yunnan)

Altitude: 3000-4850m

Notes

Doubtfully distinct from R. selense subsp. dasycladum but apparently with no intermediates and a more easterly distribution. Kingdon-Ward 5201 is a mixed gathering containing both taxa.

Nomenclature

Type: China, S Sichuan, in montibus supra Molien, c.4000m, 26 v 1914, Schneider 4083 (iso. E)

Flags

Occurs in Countries: CN Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Tree Fl. Colour: rose

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):277

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Rhododendron dasypetalum Balfour f. & Forrest

Much branched shrub to 75 cm. Leaves 8-15 x 3-7.5 mm, elliptic or oblong-elliptic, apex obtuse or rounded, mucronate, base broadly cuneate, sometimes with a few simple cilia near the base and on the petiole, undersurface uniformly tawny brown, densely covered with contiguous scales. inflorescence 2-flowered, pedicels lepidote and puberulous, 3-4 mm. Calyx 3 mm, lobes broadly strap-shaped, rounded, pubescent and lepidote, margin ciliate. Corolla bright purplish rose, broadly funnel-shaped, 12-15(-18) mm, lube 4—5(—8) mm, pubescent inside, pilose outside. Stamens 10, filaments pubescent towards the base. Ovary lepidote, style exceeding stamens, pubescent at base. Capsule ovoid, c. 5 mm, lepidote.

Habitat: Open stony pasture, 3500 m

Distribution: China (NW Yunnan)

Notes

Known only from one collection

Nomenclature

Type: China, Yunnan, Li-ti-ping, 3500 m, vi 1917, Forrest 13905 (holo. E, iso. K)

Flags

Occurs in Countries: CN Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: rose

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):100

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Rhododendron datiandingense Z.J.Feng

Shrub to 50cm. Body of the plant sparsely scaly. Lower branches creeping, curved, the upper spreading, grey-brown. Leaves in pseudowhorls of 3–5 near the apices of the branches. Blade 20–40 x 10–20mm, elliptic to narrowly obovate or elliptic-obovate; apex bluntly acute; margin entire but distinctly revolute; base narrowed, often decurrent; shiny dark-green above, paler below. Mid-vein and lateral veins impressed above when dry, the laterals quickly becoming obscure beneath. Petiole 3–5mm, flattened. Flower buds rounded-ovate, bracts ovate or ovate-spathulate, ciliate on the margins. Inflorescence a terminal umbel with 4–7 flowers. Pedicels 7–12mm. Flowers yellow, the calyx small; lobes reflexed, obtuse-crenulate. Corolla 8–10 x c.12mm, shortly campanulate; tube 4–5 x 3–4mm, with white hairs within the upper part; lobes 5 x 4mm, rounded-ovate; apex broadly rounded. Stamens 6mm; filaments cylindrical above, flattened below the middle, glabrous at the base, white hairy below the middle. Ovary 3mm, ovate-rounded; style shorter than the stamens, c.3mm, club-shaped, downwardly curved; stigma flattened rounded, to 5-lobed. Fruit 10–13 x 6mm, elongate-ellipsoid.

Distribution: China, Guangdong, Xinyi, Datianding. Epiphytic.

Notes

Named after Datianding, the place of the original collection.

Flowers June, Fruit Oct.

Said to be similar to R. rupivalleculatum but differing in the oblong-elliptic leaves, 2–4 x 1–2cm; the leaf apex obtuse, not recurved; the inflorescence of a 4–7- flowered umbel; the stamens and pistil much shorter, and the ellipsoidal capsule. Very reminiscent of R. rushforthii in the umbellate inflorescence. The much smaller vegetative measurements may be accounted for by differences between growing in cultivation and in a harsh wild environment but the lack of description of the indumentum on the ovary and style leaves doubt about the identity of this species. Only an examination of the type specimen will settle the matter of whether these two species are truly different. Rhododendron datiandingense is the older name by a few months and would take precedence if they are found to be conspecific.

Nomenclature

Type: Z.J. Feng 54123, 10 June 1990. Datianding, Xinyi, Guangdong, China (CANT).

Flags

Occurs in Countries: CN Subgenus: Vireya Habit: Non-Tree

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:35

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Rhododendron dauricum Linnaeus

Straggling shrubs, 0.5-1.5 m. Young growth lepidote and puberulous. At least some of the leaves overwintering, coriaceous, glabrous except for the shortly puberulent upper surface of the midrib, obtuse to retuse at the apex, densely lepidote beneath, 10-36 x 5-20 mm. Pedicels very short, obscure. Calyx very small, rim-like, densely lepidote. Corolla 14-21 mm, tube 5-11 mm, 20-35 mm in diameter, pink or violet-pink, pilose outside near the base, ± elepidote. Stamens 10, exserted, filaments pubescent towards the base, anthers grey. Ovary lepidote, style glabrous. Capsule ovoid, lepidote.

Distribution: USSR (eastern Siberia, Altai mountains, Angara-Sayan region, Ussuri region, Dahuria, region around the river Lena), MONGOLIA, China (northern part, adjacent to Mongolia), Japan (Hokkaido)

Illustrations:

Notes

R. dauricum is a widely distributed and variable species. Two variants have been described as separate species in the Russian literature, but I have not seen enough material to judge their distinctness. They are: R. ledebourii Pojarkova in Komarov (ed.) Fl. S.S.S.R. 18:722, t. 2 f. 3 (1952), Type: USSR, Altai, nr mouth of river Kainzci, on stony slopes, 11 vii 1915, Krylov (LE); and R. sichotense Pojarkova, loc. cit., t. 2 f. 1, Type: USSR, Reg. Ussuri, around the Olga bay, 28 iv 1913, Bjeloussov (LE)

Nomenclature

Type: Habitat in Dauria'

Flags

Occurs in Countries: CN, JP, MN, RU Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: pink

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):112

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Rhododendron davidii Franchet

Shrub or tree,3-8m. Leaves oblanceolate, 9.5-15.5 x 2-3cm,3.5-5.2 x as long as broad, apex long-acuminate to shortly cuspidate, base cuneate, lower surface glabrous; petioles 1.5-2.5 cm, glabrous. Inflorescence 7-12-flowered; rhachis 25-60 mm; pedicels 15-20 mm, stipitate-glandular. Calyx 1 -2 mm, stipitate-glandular. Corolla 7-8-lobed, open-campanulate, sparsely glandular outside, glabrous within, pink to rose-purple, with darker flecks, 40-55 mm. Stamens 14-16, filaments glabrous. Ovary stipitate-glandular; style glabrous or with a few glands and then usually only at the base, only occasionally for up to two-thirds of its length, stigma capitate. Capsule unknown.

Habitat: Open places, bamboo thickets

Distribution: China (C & S Sichuan, NE Yunnan)

Altitude: 1900-4000m

Illustrations:

Notes

Allied to R. huianum but lacking the well-developed calyx of that species. The style is usually ± glabrous though even the type has some glandular styles.

Nomenclature

Type: China, Sichuan, Moupine, 3000-4000 m, ii-iv 1869, PireDavid (iso. E, K)

Flags

Occurs in Countries: CN Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Tree Fl. Colour: pink, rose

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):228

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Rhododendron davidsonianum Rehder & Wilson

Shrub, 0-6-5 m. Young growth greenish or brownish. Leaves 3 or more x longer than broad, (27-)30-62 x 11-20 mm, acute at the apex, cuneate at the base, often ± V-shaped in section, lower surface densely lepidote with small brown scales with narrow rims, the darker centre making up more than Vi the diameter of the scale, 1-2 x their own diameter apart. Inflorescence open, few-flowered, pedicels lepidote, (8—)11—15 mm. Calyx disc-like or undulate, sometimes ciliate. Corolla (21-)23-27 mm, pink, pinkish lavender or lavender, ± elepidote outside. Capsule 11-13 mm

Habitat: In thickets and on forest margins

Distribution: China (SW & C Sichuan)

Altitude: 2000-3300m

Illustrations:

Nomenclature

Type: China, W Szechuan, southeast of Tachienlu, 2000-2500 m, v & x 1908, Wilson 1275 (iso. E)

Synonymy: R. charianthum Hutchinson, Bot. Mag. 142: t. 8665 (1916). Type: a cultivated specimen (holo. K)

Flags

Occurs in Countries: CN Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: lavender, pink

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):66

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Rhododendron decandrum (Makino) Makino

Shrub or small tree; young shoots soon glabrous. Leaves broadly rhombic, 2-3(-6) x 2~4cm, apex acuminate, upper surface with glands, especially on midrib and veins, also with a few scattered hairs, lower surface with scattered villose hairs and glands; petioles 10-15mm, sparsely glandular, also with villose hairs. Inflorescence 1-3-flow-ered, flowers appearing before leaves; pedicels 5-8mm, villose, densely so at base, also with glands. Calyx minute, glandular, lobes ciliate. Corolla open funnel-campanulate, 25-28mm, magenta, spotted; lobes c.20mm, narrowly oblong. Stamens 10, unequal, filaments glabrous. Ovary glandular, with a few villose hairs; style glabrous. Capsule 8-15mm, curved.

Habitat: Forested hillsides

Distribution: Japan (S Honshu, Shikoku)

Altitude: Around 800m

Illustrations:

Notes

R. dilatatum var. satsumense is described as differing from R. decandrum in its dilatate-ovate leaves, shining above, in the involucre being lightly reflexed before anthesis, in the glabrescent floral buds and in the glandular-punctate, usually not ciliate, capsules. We assume that this taxon has ten stamens since it has been allied by the original author to R. decandrum; we have not however seen any material of it.

Flags

Occurs in Countries: JP Altitude Ranges: 0 - 1,000m Subgenus: Tsutsusi Habit: Tree Fl. Colour: magenta

Chamberlain, D.F. & Rae, S.J. (1990) A Revision of Rhododendron IV Subgenus Tsutsusi. Edinburgh Journal of Botany 47(2):147

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Rhododendron decorum Franchet

Shrub or small tree, 1-6 m. Leaves oblanceolate to elliptic, (5.5—)7—15 x (2.2-)3-6.8 cm, (2-)2.3-3 x as long as broad, apex ± rounded, mucronate, base rounded, lower surface glabrous when mature except for punctulate hair bases; petioles 1.5-4 cm, glabrous. Inflorescence 7-10-flowered; rhachis 15-30 mm; pedicels 15-30 mm, stipitate-glandular. Calyx 1-3 mm, lobes minute, rounded, stipitate-glandular. Corolla 6-7-lobed, funnel-campanulate, usually sparsely glandular outside, often more densely so within, white to pale pink, with or without green or crimson flecks, 45-55(-62) mm. Stamens 14-16, filaments puberulent below. Ovary and style stipitate-glandular, glands whitish. Capsule 20-30 x c. 12 mm, usually slightly curved.

Habitat: Dry situations, in open forests and amongst scrub

Distribution: NE Burma, China (Yunnan, Sichuan, W Guizhou)

Altitude: 1800-3600m

Illustrations:

Notes

The colour of the stylar glands is not clear in all herbarium specimens. The pubescent stamens have therefore been used for differentiating R. decorum from the closely related R. vernicosum. Some ± intermediate plants occur in one or two localities, suggesting local hybridisation (Rock 24619, 25172, etc.). Some specimens (e.g. Forrest 11916ScFarrer979) approachR. diaprepesm the size of their corollas or leaves; these apparently occur at lower altitudes than is usual for R. decorum. One specimen (Rock 16474), assumed to be a hybrid of R. decorum, differs in its sparsely dendroid-tomentose ovary and style base with glands extending only half way up the style.

Nomenclature

Type: China, Sichuan, Moupine, 3000 m, Pere David (n.v.); ad montem Tsong Chan, 2200 m, Delavay 1123 (n.v.); supra Ta-pin-tze, 22 v 1886, Delavay, s.n. (E,K)

Synonymy: R. franchetianum Leveille, Bull. Soc. Agric. Sarthe 39: 45 (1903). Syntypes: China, Yunnan, environs de Yunnan-sen, 11 xi 1896, Bodinier (E) & 28 iii 1897, Ducloux (E). R. spooneri Hemsley & Wilson, Kew Bull. 1910: 110 (1910). Syntypes: China, W Sichuan, nr Tatsien-lu, 2650-3650 m, vi 1904, Wilson 3975 (A); NW Yunnan, Tsekou, Monbeig (K). R. giraudissii Leveille, Feddes Repert. 18: 340 (1914). Type: China, E Yunnan, mont de Siao-ou-long, 2700 m, vi 1913, Maire (holo. E)

Flags

Occurs in Countries: CN, MM Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Hymenanthes Habit: Tree Fl. Colour: crimson, green, pink, white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):230

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Rhododendron dekatanum Cowan

Very similar to R. sulfureum, differing as follows: leaves broadly ovate-oblong, 45-50 x 27-30 mm, the scales beneath contiguous, markedly unequal, flat, borne above the surface, not obviously sunk in pits; corolla c. 25 mm, tube 16 mm

Habitat: Rhododendron and bamboo forest

Distribution: China (S Xizang)

Notes

Known only from the type collection. A specimen hitherto identified as R. sulfureum (Burma, Kaw-ji pass, 10500 ft, Farrer 1550) has scales which match those of dekatanum; in other respects it is typical of sulfureum, and its status is uncertain.

Nomenclature

Type: China, SE Tibet, Chayul Chu, Natrampa, Ludlow & Sherriff 1360 (holo. BM, iso. E)

Flags

Occurs in Countries: CN Subgenus: Rhododendron Habit: Non-Tree

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):136

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Rhododendron delicatulum Sleumer

Notes

Latin – delicatulus – delicate, alluding to the delicate or dainty nature of the specimen.

Nomenclature

Type: Brass 11876, Jan. 1939. New Guinea (W), Northern part, 15km SW of Bernhard Camp, Idenburg River, mossy forest (A).

Flags

Occurs in Countries: ID Altitude Ranges: 1,000 - 2,000m Subgenus: Vireya Fl. Colour: yellow

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:79

Rhododendron delicatulum var. delicatulum

Shrub to 50cm. Twigs 1–2mm in diameter, very slender, rounded, laxly leafy, the tips densely stellate-scaly, glabrescent below; internodes 3–6cm. Leaves 3–4 together in pseudowhorls at the upper nodes. Blade 30–65 x 4–7mm, very narrowly ovate-elliptic to almost linear, mostly widest below the middle; apex gradually acuminate and somewhat curved, sub-acute; margin slightly revolute; base broadly tapering to nearly rounded; very young leaves densely covered on both sides with deeply stellately divided or shortly dendroid scales, which are on top of persistent epidermal tubercles, early glabrescent and rough to the touch above, slowly so beneath. Mid-vein impressed above, prominent beneath; lateral veins obscure. Petiole c.2 x 0.5–0.7mm, scaly. Bracts to 20 x 6mm; outer bracts subulate; inner ones ovate, with a subulate acumen for the ultimate 3–10mm, densely stellately scaly outside, glabrous internally, fringed with scales. Bracteoles to 15 x 1mm, linear-sub-­spathulate, very laxly hairy. Inflorescence c.3-flowered. Pedicels c.12mm, slender, densely reddish-brown stellately scaly. Flowers hanging or half-hanging. Calyx c.2mm in diameter, small, oblique, circular or obscurely lobed, thin, stellately scaly, shortly fringed. Corolla c.27mm, tubular below, widened at the mouth, zygomorphic, pink; tube 15–18 x 3 x 6mm, sub-densely, shortly, whitish hairy (but not scaly) outside, laxly hairy inside; lobes 5–7 x 5–6mm, spreading, broadly obovate-spathulate or sub-circular. Stamens almost equalling the corolla in length; filaments filiform, very laxly hairy proximally, glabrous distally; anthers 1.3 x 0.8mm, broadly oblong. Disc very shortly yellowish hairy at the upper margin, glabrous below. Ovary c.5 x 1.8mm, conical-cylindric, densely dark-brown stellately scaly, gradually tapering distally; style slender, as long as the corolla and covered with spreading yellowish hairs to the top; stigma sub-globose.

Habitat: Mossy forest

Distribution: Indonesia, New Guinea (W), Bernard Camp, Idenburg R.

Altitude: Around 1800m

Notes

Known only from the type collection.

Rhododendron delicatulum var. lanceolatoides Sleumer

Differing from the type in that the leaves are wider, 25–50 x 7–12mm, and the pedicels shorter, 5–7mm.

Habitat: On peaty soil

Distribution: Indonesia, New Guinea (W), Star Mts, 1km E of the mouth of the Minam R. in the Bon R.

Altitude: Around 1500m

Notes

Latin – lanceolatus – spear-shaped, the leaves being lanceolate in shape.

Once collected.

Nomenclature

Type: Kalkman 4400 (A, L).

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Rhododendron dendricola Hutchinson

Epiphytic or free-growing shrub. Young growth rarely loriform-setose. Leaves narrowly elliptic to narrowly obovate, tapered to the base, rather abruptly acute or with a short drip-tip, 70-120 x 30-48 mm, undersurface with a covering of scales of variable density. Calyx disc-like or very obscurely lobed, not loriform-ciliate. Corolla white, often with a yellow, orange or greenish blotch and/or flushed pink, lepidote outside, pilose at the base of the tube. Ovary lepidote, usually waisted towards the apex. Capsule up to 20 mm.

Distribution: India (Arunachal Pradesh), ne Burma, China (NW, W & C Yunnan, SE Xizang). Rocks, cliffs, etc., or epiphytic, 1200-1400 m

Illustrations:

Notes

A very variable species in terms of indumentum, density of scales and corolla colour; all this variation is, however, continuous. Its distribution is rather disjunct, with one main mass of records in the Taron valley (c. 28° N), the other further south in the Salween valley (c. 25-26° N). In spite of this, no clear distinction into two units can be made.

Nomenclature

Type: N Burma, Nwai valley, 11 v 1914, Kingdon Ward 1538 (holo. E)

Synonymy: R. atentsiense Handel-Mazzetti, Anz. Akad. Wiss. Wien 18:14 (1921). Type: China, Yunnan bor.-occid., in monte inter pagum Atentse et fluvium Mekong sito, versus .4000 m, 1914, Gebauer (holo. WU—n.v., iso. E). R. notatum Hutchinson, Notes R.B.G. Edinb. 16:177 (1931). Type: Upper Burma, Seinghku Wang, 5000-5500 ft, Kingdon Ward 6711 (holo. E). R. taronense Hutchinson, op. cit.: 178. Type: China, Yunnan, Taron valley, 4000-5000 ft, Kingdon Ward 5501 (holo. E)

Flags

Occurs in Countries: CN, IN, MM Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: green, orange, pink, yellow

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):48

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Rhododendron dendrocharis Franchet

Very similar to R. moupinense, differing as follows: shrub to 0-7 m; leaves 13-17 x 6-10 mm; calyx lobes up to 3 mm, ± elepidote; corolla rose pink, 20-22 mm, tube 10-13 mm; style shorter than stamens. Capsule unknown.

Habitat: On old logs

Distribution: China (C Sichuan)

Altitude: 2600-3000m

Illustrations:

Nomenclature

Type: China, Mupin, ad truncos putridos, in sylvis regionis altissimae, v 1869, David (holo. P—n.v., iso. E)

Flags

Occurs in Countries: CN Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: pink

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):58

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Rhododendron densifolium K.M.Feng

Shrub to 1.3m. Twigs c.1.5mm in diameter, red or green, densely covered with warty scale bases and brown scales; internodes 3–10mm. Leaves in loose pseudo­whorls, 7–15 together, 5–15mm apart, when in exposed places, clustered at the ends of the twigs. Blade 6–12 x 3.5–5mm, obovate, spathulate; apex emarginate and mucronate with a small gland at the apex; margin entire and revolute; base tapering; upper surface green shiny and glabrescent; lower surface paler green, sparsely but persistently scaly. Scales small, brown, circular or slightly lobed with large centres. Mid-vein slightly impressed above, raised below; lateral veins obscure. Petiole 2–3 x 0.7–1mm, faintly grooved above, sparsely scaly. Flower buds to 6 x 2.5mm, ovate, green, turning brown before opening, smooth, glabrous except along the margins of the bracts. Outer bracts ovate, glabrous with shortly ciliate margins. Inflorescence of solitary flowers held horizontally to half-hanging. Flowers 6–7 x 15–18mm. Pedicels 9–14 x 1mm, sparsely scaly, without hairs. Calyx shallowly 5-lobed, lobes c.1.5–2 x 1.5mm, scaly outside. Corolla 8–10mm, campanulate, yellow, without spots or visible markings; tube c.5 x 4 x 4mm, sparsely scaly outside, hairy inside, lobes 6–7 x 3.5–4.5mm, elliptic, spreading to the horizontal or slightly reflexed, not or only slightly overlapping. Stamens exserted to c.5mm, arranged all round the mouth, filaments hairy; anthers brown. Ovary ovoid, densely scaly and hairy; style 2–4mm, curved downwards; stigma globose. Fruit 7–11 x 3–4mm, with a persistent style. Seeds 4mm, without tails c.1mm, the longest tail 1.5mm.

Habitat: In mixed forests on the ground in light shade or exposed on ridges on rocky sometimes limestone mountains

Distribution: China, SE Yunnan, Malipo and Xichou.

Altitude: 1000-1800m

Notes

Latin – densus – dense; folium – leaf. Alluding to the densely leafy stems.

Flowers Sept.–Oct., although one plant was flowering in June. The fruit said to be ripe Sept.–Oct. of the following year.

Very similar to R. emarginatum but with consistently smaller, narrower leaves which gradually broaden upwards to near the apex. It also has hairs on the ovary as well as scales. It might be thought to be a high altitude form of R. emarginatum except that this species is reported at even higher altitudes than R. densifolium. These two species do grow together in the wild and are clearly distinct on leaf size. The marginal hairs on the bracts are exceptionally short, barely reaching 0.1mm. Recently introduced into cultivation but not yet known to have flowered.

Nomenclature

Type: K.M. Feng 12815, 3 Nov. 1947. Yunnan, Mar-li-po: Chung-dzai, 1600–1800m (KUN)

Flags

Occurs in Countries: CN Altitude Ranges: 0 - 1,000m: 1,000 - 2,000m Subgenus: Vireya Habit: Non-Tree Fl. Colour: yellow

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:33

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Rhododendron denudatum Leveille

Shrub, 2-3m. Leaves sub-coriaceous, elliptic, 12.5-20 X 4-7cm, 2.5-3 x as long as broad, apex apiculate, upper surface glabrous, with impressed veins, lower surface with a bistrate indumentum, the lower layer whitish, compacted and adpressed, the upper yellow to cinnamon, even when mature, lanate, ± detersile, hairs ramiform, sometimes lacking on the older leaves, veins prominent and ± glabrous; petioles 1— 2cm, tomentose. Inflorescence 8—10-flowered; rhachis up to 7mm; pedicels 10-15mm, densely tomentose. Calyx c.lmm, tomentose, lobes minute. Corolla campanulate, rose to wine-red, probably with interior markings, c.40mm. Ovary densely whitish-tomentose; style glabrous. Capsule not known.

Habitat: Mountains

Distribution: China (C & S Sichuan, NE Yunnan, NW Guizhou)

Altitude: 3100-3300m

Notes

Closely allied to R. floribundum and doubtfully distinct. The" leaves are apparently thinner and also differ in the detersile yellowish upper layer of the indumentum.

Nomenclature

Type: China, Yunnan, rochers de Tien Sin, iv 1911, Maire (holo. E; iso. K).

Synonymy: R. xanthoneuron Leveille, ibid. 13: 340 (1914). Type: China, Yunnan, Mont Ta-Pe-Lou, 3200m, v 1911, Maire (holo. E)

Flags

Occurs in Countries: CN Altitude Ranges: 3,000 - 4,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: rose

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):321

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Rhododendron detersile Franchet

Dwarf shrub, 0.3- lm; perulae persistent. Leaves oblanceolate to elliptic, 4-5 x 1.5-1.8cm, c.2.7 x as long as broad, apex acute, base cuneate, upper surface with impressed veins so appearing bullate, lower surface with a unistrate red-brown detersile lanate ramiform indumentum; petioles c.0.5cm, densely tomentose. Inflorescence c.lO-flowered; pedicels c.lOmm, densely glandular-hirsute. Calyx c.3mm, densely hairy and stipitate-glandular, lobes ligulate, rounded. Corolla campanulate, pinkish, 25-30mm. Ovary glandular-pilose; style glandular in the lower half. Capsule not known.

Habitat: Rocky slopes

Distribution: China (E Sichuan)

Altitude: Around 2500m

Notes

Only known from material collected by Farges near the type locality. The bullate leaves and leaf indumentum suggest a distant affinity with R. mltonii but the glandular ovary and well-developed calyx suggest that it is closer to R. adenogynum and its immediate allies.

Nomenclature

Type: China, E Sichuan, rochers de Touan tchen, s.p. de Ta-lin-hien, 2500m, Farges 1382 (iso. E,K).

Flags

Occurs in Countries: CN Altitude Ranges: 2,000 - 3,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: pink

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):337

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Rhododendron detznerianum Sleumer

Rigidly erect shrub to 1.5m. Twigs with shortly stalked scales, later rough and minutely warty after the scales have fallen. Leaves densely spirally arranged. Blade 10–15 x 2–4mm, elliptic to spathulate; apex broadly acute to obtuse, margin narrowly revolute, sub-crenulate with scale attachments; base narrowly tapering, decurrent, laxly scaly above but quickly glabrescent, below sub-densely and persistently scaly. Scales with a narrow marginal flange and thick rounded and partly impressed centre. Mid-vein impressed above, slightly raised below; lateral veins and reticulation not visible. Petiole c.1mm, scaly. Bracts to 4mm, ovate sub-acuminate to apiculate, outside scaly along the middle line, without hairs except for the ciliate margins. Inflorescence of 1–3 vertically hanging flowers. Pedicels 6–8mm, slender, densely scaly but without hairs. Calyx c.2.5mm in diameter, shortly 5-lobed, densely scaly. Corolla c.12mm, red, cylindrical; tube c.10 x 3 x 4mm, densely scaly outside, glabrous inside; lobes c.3 x 3mm, sub-circular, semi-erect, scaly outside, without hairs but with a denticulate margin. Stamens as long as the corolla tube; filaments c.10mm, glabrous; anthers 1.5mm, broadly oblong. Disc glabrous but with scales on the upper side. Ovary c.2 x 1mm, cylindrical, vertically striate, densely round-scaly; style c.8mm, slender, densely scaly for the proximal 1mm, glabrous distally; stigma club-shaped. Fruit 6–7 x c.3mm, sub-cylindrical.

Habitat: In the grassland border with Podocarpus/Papuacedrus forest, and tree fern grassland

Distribution: Papua New Guinea, Central District, Goilala subdistrict, Mt Dickson; Morobe District, above Bakaia, c.15 miles SE of Garaina.

Altitude: 2745-3500m

Notes

Dedicated to the memory of H. Detzner, an admirer of New Guinea rhododendrons who was in the Mt Dickson area with the Kaiser Wilhelm Land Boundary Commission in 1914.

Said to be closely related to R. erosipetalum from the Vogelkop Peninsula but that species has bracts and pedicels which are both hairy and scaly outside and also has hairs on the corolla lobes.

Nomenclature

Type: Hartley 12959, 10 Feb. 1964. New Guinea (E), Central District, Goilala subdistrict, Mt Dickson, 3500m (L, CANB, K, LAE).

Flags

Occurs in Countries: PG Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Vireya Habit: Non-Tree

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:58

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Rhododendron dianthosmum Sleumer

Shrub to 2m. Twigs slender, densely scaly, early glabrescent and often whitish; internodes 6–16cm. Leaves 3–4 together in pseudowhorls at the upper 2 or 3 nodes. Blade 70–140 x 30–55mm, broadly elliptic or elliptic or slightly obovate; apex broadly acute to obtuse; margin entire, flat, a little recurved when dry; base broadly tapering to rounded, young leaves densely reddish-brown stellate-scaly, mature ones glabrescent, on both sides covered with numerous epidermal tubercles which make them feel rough to the touch. Scales dendroid; marginal zone divided to, or almost to, the centre; centre small, deepened or prolonged into a short stalk. Mid-vein slightly prominent proximally above, gradually becoming flat in the distal part above; below as thick as the petiole in the proximal part, gradually decreasing distally; lateral veins 8–12 per side, irregular, inarched before the margin, slightly prominent on both sides, veins laxly reticulate, not very conspicuous. Petiole 10–15 x 2–2.5mm, densely scaly initially. Bracts 10–35 x 10–15mm, dull red; outer ones ovate, inner ones elliptic-ovate and apiculate, innermost ones broadly spathulate, scaly and/or appressed-hairy. Bract­eoles c.20 x 1–2mm, linear, glabrous. Inflorescence a 3–6-flowered open umbel, the flowers held stiffly horizontally or half-hanging. Pedicels 10–15 x 1.5mm, very densely brown stellate-scaly, without hairs. Calyx c.3mm in diameter, obliquely disc-shaped. Corolla 50–70 x c.70mm, pure white, or pink with darker pink edges, with a scent of carnations; tube 25–40 x 6–10 x 12–15mm, tubular, straight, glabrous outside, shortly hairy inside; lobes 6–7 in number, 20–35 x 20–30mm, spathulate, 3 or 4 of them generally smaller than the others, horizontally spreading. Stamens exserted to c.10mm; filaments linear, densely or more laxly hairy in the proximal ¾, glabrous distally; anthers 3.5–4 x c.1mm, elongate-oblong, the base obtuse. Disc glabrous below, hairy at the upper margin. Ovary 8–10 x 2–3mm, sub-cylindrical, covered with whitish to yellowish, distally directed hairs, which cover the scales, tapering gradually; style c.30mm, slender, densely hairy proximally, the hairs becoming laxer distally and completely glabrous in the uppermost ¼, without scales; stigma 2.5–3mm.

Habitat: Epiphytic in primary forest, 800–1400m, descending along ravines to c.500m.

Distribution: Indonesia, New Guinea (W), above Jayapura on the W slope of Mt Dafonsero; Cycloop Mts, Faita R. camp and along path from Ifar to Ormu.

Altitude: 500-1400m

Notes

Named after the genus Dianthus because the flowers have a similar perfume.

In cultivation since 1961 when Professor Sleumer sent seed from New Guinea to the USA from where it has been distributed. Probably all genuine materials of this species are from this introduction. Slow growing and fairly compact.

Nomenclature

Type: van Royen & Sleumer 5736, 8 June 1961. New Guinea (N), Cycloop Mts, Faita R. camp (L, A, CANB).

Flags

Occurs in Countries: ID Altitude Ranges: 0 - 1,000m: 1,000 - 2,000m Subgenus: Vireya Habit: Epiphyte, Non-Tree

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:79

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Rhododendron diaprepes Balfour f. &W. W. Smith

Shrub or tree, 1-14 m. Leaves elliptic-oblong to ovate, 12—19(—30) x 4.4-11 cm, 1.7-3 x as long as broad, apex ± rounded and minutely mucronate, base rounded, lower surface glabrous when mature except for persistent punctulate hair bases; petioles 2-3.5 cm, glabrous. Inflorescence 5-10-flowered; rhachis 15-20 mm; pedicels 15-30 mm, ± stipitate-glandular. Calyx 2-6 mm, lobes shallow to well-developed, stipitate-glandular. Corolla 7—8-lobed, open- to funnel-campanulate, ± glandular outside, puberulent within, white, sometimes flushed rose, (65-)80-100 mm. Stamens 18-20, filaments puberulent below. Ovary and entire style with white-stipitate glands. Capsule 30-60 x 12 mm, curved

Distribution: NE Burma, China (W Yunnan), Laos

Illustrations:

Notes

Closely allied to R. decorum but with larger leaves and corollas, also close to R.faithae(q.v.)

Further material seen since the completion of the manuscript suggests that R. diaprepes is best treated as a subspecies of R. decorum as several intermediate specimens are now known from the extreme western part of Yunnan, within the range of R. diaprepes. The necessary combination is R. decorum Franchet subsp. diaprepes (Balfour f. & W. W. Smith) T. L. Ming, based on R. diaprepes as cited above.

Nomenclature

Type: China, W Yunnan, Shweli/Salween Divide, 9000 ft, vi 1913, Forrest 11958 (holo. E; iso. K)

Synonymy: R. rarile Balfour f. & W. W. Smith, ibid. 10: 139 (1917). Type: China, W Yunnan, hills around Tengyueh, 6000-7000 ft, v 1912, Forrest 7940 (holo. E)

Flags

Occurs in Countries: CN, MM Subgenus: Hymenanthes Habit: Tree Fl. Colour: rose, white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):233

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Rhododendron dichroanthum Diels

Dwarf shrub, 0.3-2.3m; young shoots with a white floccose indumentum, sometimes also glandular- or eglandular-setose; perulae deciduous. Leaves oblanceolate to elliptic, 4—9.5 X 2-4cm, 1.9-3.2 x as long as broad, apex apiculate, base ± rounded to cuneate, glabrous above, with a continuous silvery to fawn, ± loose to compacted rosulate indumentum beneath; petioles 0.5-lcm, indumentum white, floccose. Inflorescence 3-6-flowered; rhachis 5(-8)mm; pedicels 15-25mm, rufous-tomentose or stipitate-glandular. Calyx 3-15mm, coloured, cupular when well-developed, though usually irregular, glabrous except for the rounded, glandular-ciliate lobes. Corolla fleshy, tubular-campanulate, orange-red, occasionally yellow flushed red or even carmine, 35-50mm. Ovary rufous-tomentose, with or without stipitate glands. Capsule 10-15 x 4-6mm.

Habitat: Open rocky slopes, cliff ledges, cane brakes, etc.

Altitude: 2750-4550m

Notes

A variable species showing some geographical variation; closely allied to R. sanguineum. A specimen, Forrest 27071, with yellow flowers flushed rose, sparsely hairy leaves and persistent perulae, is almost certainly a hybrid between R. dichroanthum and R. aperantum.

Flags

Occurs in Countries: CN, MM Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: carmine, orange, red, yellow

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):393

Rhododendron dichroanthum subsp. apodectum (Balfour f. & W. W. Smith) Cowan

Ovary lacking stipitate glands, rarely with one or two towards the base; young shoots with eglandular setae or setae absent. Leaves 1.9-2.4(-2.5) x as long as broad; silvery to fawn.

Distribution: China (W Yunnan), ne Upper Burma

Illustrations:

  • Bot. Mag. 149: t.9014 (1924)
Nomenclature

Synonymy: R. apodectum Balfour f. & W. W. Smith, Notes R.B.G. Edinb. 10: 83 (1917). Type: China, Yunnan, western flank of the Tali Range, 25°20'N, 10-11000ft, viii 1912, Forrest mi (holo. E; iso. K). R. jangtzowense Balfour f. & Forrest, Notes R.B.G. Edinb. 13: 271 (1922). Type: China, W Yunnan, Shweli/Salween divide, Jangtzow Shan, 11000ft, vi 1919, Forrest 18167 (holo. E; iso. K). R. liratum Balfour f. & Forrest, ibid. 13: 274 (1922). Type: China, W Yunnan, Shweli/Salween divide, Jangtzow Shan, 11000ft, vi 1919, Forrest 18153 (holo. E; iso. K).

Rhododendron dichroanthum subsp. dichroanthum

Ovary lacking stipitate glands, rarely with one or two towards the base; young shoots with eglandular setae or setae absent. Indumentum silvery, compacted; leaves 2.5-3 x as long as broad.

Illustrations:

  • Bot. Mag. 145: t.8815 (1919)
  • Gard. Chron. 79: 383 (1926). china (W Yunnan, around Dali)
Nomenclature

Type: China, Yunnan, E flank of the Tali Range, 9-10000ft, vii 1916, Forrest 4138 (holo. E; iso. K)

Rhododendron dichroanthum subsp. scyphocalyx (Balfour f. & Forrest) Cowan

Ovary with a number of stipitate glands; young shoots often glandular-setose. Leaves 1.9-2.5(-2.7) x as long as broad.

Distribution: NE Upper Burma, China (W Yunnan)

Nomenclature

Synonymy: R. scyphocalyx Balfour f. & Forrest, Notes R.B.G. Edinb. 13: 291 (1922). Type: NE Upper Burma, western flank of the N'Maikha/ Salween divide, 26°25'N, v 1919, Forrest 18050 (holo. E). R. herpesticum Balfour f. & Kingdon-Ward, Notes R.B.G. Edinb. 10:114 (1917). Type: E Upper Burma, Mwai divide, Ridge of Naung Chanung, 12-13000ft, 16 vii 1914, Kingdon-Ward 1793 (holo. E; iso. K). R. torquatum Balfour f. & Farrer, Notes R.B.G. Edinb. 13: 303 (1922). Type: NE Upper Burma, Maguchi Pass, 11-12000ft, 31 vii 1920, Farrer 1775 (holo. E). R. dichroanthum Diels subsp. herpesticum (Balfour f. & Kingdon-Ward) Cowan, Notes R.B.G. Edinb. 20: 87 (1940).

Rhododendron dichroanthum subsp. septentrionale Cowan

Ovary with a number of stipitate glands; young shoots often glandular-setose. Leaves 3-3.3 x as long as broad. Indumentum whitish to fawn, leaves 3-3.3 x as long as broad.

Nomenclature

Type: NE Upper Burma, western flank of the Salween/Kiu-chiang divide, 27°18'N, 98°40'E, 13-14000ft, vii 1924, Forrest 25750 (holo. E).

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Rhododendron dielsianum Schltr.

Notes

Named after Friedrich L.E. Diels, 1874–1945, a German botanist.

Nomenclature

Type: Schlechter 17770. New Guinea (NE), Kani Mts, Above Bolobo, c.1400m (B†, P).

Synonymy: R. laureola Schltr., Bot. Jahr. 1918. 55: 151.

Flags

Occurs in Countries: PG Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Vireya

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:80

Rhododendron dielsianum var. dielsianum

Shrub to 1.5m. Twigs rounded, 1.5–3mm in diameter, the tips densely brown with stellate scales which give an almost hairy appearance; older parts glabrescent, smooth, brown; internodes 1.5–8cm. Leaves mostly 3–4 together in tight pseudowhorls at the upper 2–3 nodes. Blade 30–55 x 8–25mm, elliptic; apex shortly acuminate, apiculate, sub-acute; margin flat or slightly revolute; base broadly tapering, or rarely almost rounded; densely scaly on both sides initially, quickly glabrescent above, more persistently scaly beneath especially near the mid-vein, finally glabrescent and a little rough to the touch on both sides. Scales small, deeply stellately divided, sessile or shortly dendroid and on top of low, persistent, epidermal tubercles. Mid-vein somewhat impressed above, raised beneath; lateral veins c.6 per side, very faintly impressed above and raised beneath, inconspicuous on both sides. Petiole 2–5mm, grooved above, slender, densely scaly. Flower buds to 18 x 6mm, slenderly ellipsoid or ovate, the apex acute, the bract tips appressed or only slightly spreading. Bracts to 15 x 6mm; the outer subulate, often with the point as long as the broad part; inner ones ovate-subulate to ovate-apiculate, stellate-scaly in the upper ½ and shortly fringed with stalked scales. Bracteoles to c.10mm, filiform, laxly scaly. Inflorescence of mostly solitary or paired flowers, hanging or half-hanging, rarely in up to 5-flowered open umbels. Pedicels 10–13mm, slender, densely brown-stellate-scaly. Calyx c.2.5mm in diameter, often slightly oblique, disc-shaped, densely stellately scaly, very shortly obtusely 5-lobed. Corolla 25–35 x 11–14mm, tubular to c.4⁄5 of its total length, slightly curved and zygomorphic, pale pink; tube 12–20 x 8–10 x 6–8mm, slightly laterally compressed, narrowest about the middle, weakly pouched at the base, sparsely scaly outside, glabrous or sparsely hairy inside; lobes c.6–8 x 5–7mm, broadly spathulate to sub-circular, spreading. Stamens clustered on the upper side of the flower, unequal, the longest exserted from the mouth to c.6mm, shorter ones at the mouth; filaments red, linear to filiform, glabrous or very slightly hairy; anthers c.2 x 1mm, brown. Disc prom­inent, glabrous. Ovary 5–6 x c.1.5mm, sub-cylindrical, densely stellate-scaly, gradually tapering distally; style slender, glabrous or scaly at the very base only, becoming slightly exserted from the mouth when receptive; stigma sub-globose, slightly 5-lobed. Fruit 17–30 x 3–5mm, cylindrical, grooved longitudinally and often curved. Seeds 40–52mm, without tails 10–11mm, the longest tail c.25mm, irregularly crimped.

Habitat: Epiphytic on tall trees in ravines and wooded slopes, in dense shade, terrestrial in secondary grassland and along roadsides

Distribution: Papua New Guinea, Upper Sepik R. region; Kani, Finisterre and Saruwaged Mts. Common in the Eastern Highlands, also in the Simbu and Western Highlands. Possibly in W New Guinea; see notes under R. bryophilum.

Altitude: 1200-1940m

Rhododendron dielsianum var. stylotrichum Sleumer

Slender erect shrub to 3m. Corolla pink. Differs from var. dielsianum by the style which is laxly shortly hairy with spreading hairs in its lower ½.

Habitat: Hillside secondary grasslands locally common.

Distribution: Papua New Guinea, Eastern Highlands: Upper Dunantina Valley, the road between Kami and Lufa and Mt Kesegete, Namaro, Benabena District.

Altitude: 1700-2000m

Notes

Latin – stylus – the style; trichoma – hair. Alluding to the hairs at the base of the style which distinguishes this variety from the type one.

Nomenclature

Type: Hoogland & Pullen 5307. Papua New Guinea, Eastern Highlands, Goroka subdistrict, Upper Dunantina valley, near Sosomepari village (LAE, B, BRI, CANB, K, L).

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Rhododendron dignabile Cowan

Shrub or small tree, 0.6-6m. Leaves elliptic to obovate-lanceolate, 7.5-18 x 4-6.5cm, 1.8-2.7 x as long as broad, apex acute to apiculate, base cordate to ± rounded, lower surface with a thin discontinuous unistrate brown indumentum composed of the scattered remains of hairs and glands; petioles 0.5-2cm, sparsely floccose or glabrescent. Inflorescence 5- 15-flowered; rhachis c.lOmm; pedicels 5-20mm, glabrescent or sparsely floccose. Calyx 0.5-3mm, lobes rounded, usually glandular-ciliate. Corolla campanulatc to funnel-campanulate, white to yellow, sometimes flushed pink, with or without purple flecks and basal blotch, 25-45mm. Ovary glabrous or with a brownish-red floccose indumentum, sometimes interspersed with glands; style usually glabrous, occasionally glandular below. Capsule not known.

Habitat: Forests, open stony slopes

Distribution: China (E Xizang)

Altitude: 3350-4550m

Notes

A variable species. Specimens from open habitats are significantly smaller, with shorter corollas and leaves. There also appears to be considerable variation in the amount of indumentum on the ovaries.

Nomenclature

Type: China, SE Xizang, Le La (Kyimpu), Chayul Charme, 13000ft, 9 v 1936, Ludlow & Sherriff 1564 (holo. BM; iso. E).

Flags

Occurs in Countries: CN Altitude Ranges: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Tree Fl. Colour: pink, purple, white, yellow

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):365

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Rhododendron dilatatum Miquel

Shrub or small tree; shoots glabrous. Leaves rhombic, 3-5 x 1.5-3.5cm, apex acuminate, both surfaces covered with adpressed pilose hairs when young, at maturity upper surface glabrous, lower surface with sparse pilose hairs; petioles 3~5mm, papillate. Inflorescence 1-3-flowered, flowers appearing before leaves; pedicels 5-8mm, covered with adpressed brown hairs and glands. Calyx minute, glandular, lobes ciliate. Corolla open funnel-shaped, 20-30mm, rose-purple, lobes 15-25mm, oblong. Stamens 5, filaments glabrous. Ovary glandular; style glabrous.

Distribution: Japan (S Honshu)

Altitude: Around 1000m

Illustrations:

Notes

Rehder states that the type lacks flowers. Therefore our concept of R. dilatatum follows that of Maximovicz (in Rhododendr. As. Orient. 27, 1870).

Flags

Occurs in Countries: JP Altitude Ranges: 0 - 1,000m: 1,000 - 2,000m Subgenus: Tsutsusi Habit: Tree Fl. Colour: rose

Chamberlain, D.F. & Rae, S.J. (1990) A Revision of Rhododendron IV Subgenus Tsutsusi. Edinburgh Journal of Botany 47(2):146

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Rhododendron dimitrium Balfour f. & Forrest

Shrub, 1 — 3m. Leaves coriaceous, oblanceolate to elliptic, 6.5—9 X 2.2-3.2cm, c.3 x as long as broad, apex acuminate to apiculate, base ± cuneate, with lamina narrowly decurrent, margin with red sessile glands, entirely glabrous at maturity, lower epidermis epapillate; petioles 0.7-1cm, floccose-hairy at first, soon giabrescent. Inflorescence lax, 8—12-flowered; rhachis c.lOmm; pedicels 7-10mm, dendroid-tomentose. Calyx cupular, up to 10mm, lobes broadly ovate, glabrous except for the gland-fringed margin. Corolla tubular-campanulate, white flushed rose to deep rose-pink, with at least a few purple flecks, papillate-pubescent within towards base, 35-40mm. Ovary densely tomentose, with a few stipitate glands; style tomentose, at least in the lower half. Capsule not known.

Habitat: Open thickets

Distribution: China (W Yunnan, around Dali)

Altitude: 3000-3350m

Notes

This species is apparently intermediate between subsections Irrorata and Neriiflora; the corolla suggests an alliance with the former and the well-developed calyx with the latter. R. dimitrium might be a hybrid between R. irroratum and R. neriiflorum, both of which occur in the vicinity of Dali. However, the five specimens seen suggest that a stabilised population has developed thus meriting formal taxonomic treatment.

Nomenclature

Type: China, Mid-W Yunnan, western flank of the Tali Range, 25°40'N, 10000ft, v 1917, Forrest 13736 (holo. E; iso. K).

Flags

Occurs in Countries: CN Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: purple, rose, white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):428

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Rhododendron disterigmoides Sleumer

Notes

Like a Disterigma, a genus of South American Ericaceae.

Nomenclature

Type: Brass 9022, Aug. 1938. New Guinea (N), Mt Wilhelmina, Lake Habbema, 3225m camp (A, L, fragment).

Flags

Occurs in Countries: ID, PG Altitude Ranges: 3,000 - 4,000m Subgenus: Vireya Fl. Colour: red, white

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:147

Rhododendron disterigmoides subsp. astromontium Argent

Erect shrub to 1m. Leaves shiny dark green above, light green with brown scales below, arranged in distinct pseudowhorls. Flower buds to 10 x 4mm, outer bracts broadly elliptic, with long points, inner bracts ovate, acuminate, also with long slender subulate points, completely glabrous except for a dense fringe of scales around the bract margins. Pedicels pink. Corolla deep red with white scales. Stamens pink with white pollen. Ovary brown.

Habitat: Podocarp­us–Phyllocladus woodland with Gahnia tussocks dominating the ground layer, locally common.

Distribution: Papua New Guinea, West Sepik District, Telefomin subdistrict, Ridge top W of Tel Basin, 2.5km E of Mt Capella. Indonesia, New Guinea (W), Star Mts, Mt Antares

Altitude: 3380-3800m

Notes

Latin – aster – a star; montes – mountains. Alluding to the Star Mountains where it has been collected.

Differing from the type subspecies chiefly in the distinctly pseudowhorled leaf arrangement.

Rhododendron disterigmoides was described from the Lake Habbema area in West New Guinea, not a great distance from the locality of this subspecies. The type of ssp. disterigmoides was described incompletely in that the flower buds were not collected. It is possible that flower bud characters from the type area will show sufficient difference from those of this new subspecies to warrant that this taxon be raised to specific level. Apart from the difference in leaf arrangement there are some other minor differences: the leaves of this subspecies are less revolute, the margins being so only in the proximal 1⁄3, the apices are often obtuse rather than acute to acuminate, and the leaf bases are often broadly tapering rather than rounded or sub-truncate. This subspecies has been confused in the past with R. pulleanum. It is easily distinguished on the marginal bud scale indumentum which is of simple hairs in R. pulleanum, not scales.

Nomenclature

Type: Vinas LAE 67036, 7 April 1975. Papua New Guinea, West Sepik District, Telefomin Subdistrict, Ridge-top, west of Tel Basin 2.5km E of Mt Capella, 3800m (LAE, A, BISH, CANB, E, K, L, SYD).

Rhododendron disterigmoides subsp. disterigmoides

Shrub to 80cm, with strong erect branches. Twigs 1.5–2mm in diameter, when young covered with reddish-brown, stalked, stellate scales, later glabrescent. Leaves sub-densely spirally arranged. Blade 6–10 x 4–6mm, ovate; apex acuminate, apiculate, acute; margin thickened and pale, distinctly revolute, crenulate with impressed scales; base rounded to sub-truncate; glabrescent above, persistently laxly scaly beneath. Scales small, irregularly stellate-incised, weakly or not impressed. Mid-vein obtusely prominent beneath, obscure above; lateral veins obscure. Petiole c.1mm. Inflorescence 2–4-flowered, flowers half-hanging to hanging. Pedicels 8–12mm, slender, densely shortly stalked, stellate-scaly, without hairs. Calyx c.2.5mm in diameter, shortly cup-shaped, shortly obtusely 5-lobed, densely scaly outside. Corolla 22–23mm, tubular, deep red; tube c.17 x 4 x 7mm, laxly to sub-densely scaly outside, glabrous inside; lobes c.8 x 8mm, sub-circular, with a few scales outside. Stamens exserted to c.2mm, unequal; filaments linear, glabrous; anthers c.1.8 x 1mm, broadly obovate-oblong. Disc glabrous. Ovary 4–5 x c.2mm, sub-conical-cylindrical, densely scaly gradually tapering distally; style 8–9mm, glabrous, columnar; stigma club-shaped-globose.

Habitat: A common terrestrial in shrubberies and on peaty ridges

Distribution: Indonesia, New Guinea (W), Lake Habbema.

Altitude: Around 3225m

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Rhododendron dumicola Tagg & Forrest in Stevenson (ed.)

Shrub, l-2.5m. Leaves obovate to broadly elliptic, 6.5-7.5 x 3-4cm, 1.8-2.2 x as long as broad, apex apiculate to acuminate, base rounded, lower surface with a thin unistrate lanate brown evanescent indumentum; petioles 0.5-1.5cm, glabrescent. Inflorescence 5-10-flowered; rhachis c.5mm; pedicels c.20mm, glandular-tomentose. Calyx 7-10mm, with broad chartaceous, glabrous or glandular-ciliate lobes. Corolla white flushed rose, with purple flecks, c.40mm. Ovary stipitate-glandular; style glabrous. Capsule c. 12 x 6mm, curved.

Distribution: China (NW Yunnan)

Notes

A distinctive species on account of its often acuminate leaves and well-developed calyces. The calyx is reminiscent of that found in subsection Thomsonia and it is possible that this taxon is a hybrid.

Nomenclature

Type: China, NW Yunnan, Mekong/Salween divide, 14000ft, 27°N, 99°2'E, vii 1924, Forrest 25580 (holo. E)

Flags

Occurs in Countries: CN Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: purple, rose

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):338

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Rhododendron durionifolium Becc.

Notes

Latin – Durio, the genus of fruit trees in the family Bombacaceae; folium – leaf. Alluding to the similarity of the scales on the leaf to those of a durian.

Nomenclature

Type: Beccari 3230. Malaysia, Sarawak (Borneo), Batang Lupar, Mt Tiang Laju (FI, P).

Flags

Occurs in Countries: ID, MY Altitude Ranges: 0 - 1,000m: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Vireya Habit: Tree Fl. Colour: orange, red, yellow

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:113

Rhododendron durionifolium subsp. durionifolium

Shrub or small tree to 3m. Twigs rounded, thick, initially entirely covered in the younger parts with brown to dark golden scales; internodes 3–16cm. Leaves 3–5 in pseudowhorls, in the apical part of the stem. Blade 70–170 x 20–65mm, ovate to ovate-elliptic; apex long-­acuminate to shortly caudate; margin flat or narrowly reflexed especially when dry, mostly irregularly wavy, sometimes minutely toothed; base rounded to cordate or auriculate; with very thin silvery scales above which leave small pits as they disappear, entirely and persistently covered with the orange-brown scales beneath. Scales with broad striate flanges and large swollen centres, the largest darker and forming clearly visible spots. Mid-vein distinctly impressed above, very broad and prominent beneath for at least ¾ of its length; lateral veins 6–9 per side, straight and spreading below, curved and anastomosing towards the edge, smooth or slightly impressed above in mature leaves only, indistinct beneath, veins laxly reticulate and mostly minutely impressed on the upper side only; silvery green when dry above turning green when wet, coppery orange-brown beneath. Petiole 1–4 x c.3mm, densely scaly, without a groove when fresh, but mostly very short or almost lacking. Flower buds 20–25 x 12–15mm, smooth, ovoid. Bracts to 20 x 12mm, the outer fully appressed, ovate, obtuse to sub-apiculate, the base truncate, often with minute hairs outside, scaly along the upper outer side near the middle, finely white ciliate along the margins, the inner ones spathulate. Bracteoles to 15mm, filiform, papillose-hairy, often sub-spathulate and very short-ciliate at the apex. Inflorescence an open, or more rarely, a complete umbel of 10–35 flowers. Flowers erect to spreading. Pedicels 10–15 x c.1mm, densely scaly. Calyx a very low, disc-like ring. Corolla 24–30mm, yellow? to orange, or red, tubular to narrowly funnel-shaped; tube c.5 x 5 x 8mm, mostly completely glabrous, rarely with a few (apparently rapidly falling) scales on the lower part of the tube outside, glabrous or slightly hairy at the base of the tube inside, straight, often somewhat pouched at the base; lobes c.12 x 8mm, spreading, obovate to nearly rounded, overlapping in the basal 1⁄3, as long as the corolla tube. Stamens c.20mm, spreading all round the mouth, slightly unequal; filaments linear, flattened and densely whitish hairy in the basal 1⁄3, filiform and glabrous distally; anthers 2.5–3.5 x 0.5–0.8mm, brown, oblong, often curved. Disc glabrous. Ovary 5–8 x c.1.5mm, elongate-conical, densely scaly, gradually tapering distally; style 7–10mm, thick and scaly in the proximal ½, glabrous distally; stigma rounded or slightly 5-lobed, lobes enlarging into separate club-shaped spreading parts as the fruit develops. Fruit 25–45 x 3–4mm, cylindrical, often somewhat curved, densely scaly, slightly 5-ribbed, the valves curling right back. Seeds 6mm, without tails 0.7mm, the longest tail 2.6mm.

Habitat: Widespread, growing both terrestrially and epiphytically in moss forest, low shrubberies and on bare sandstone rocks, locally common

Distribution: Malaysia (Borneo), Sarawak and Sabah. Indonesia, C and SE Borneo.

Altitude: 800-2400m

Notes

This species is extremely variable throughout its entire range but may be known amongst the section Malayovireya by its short petioles and the relatively long, tubular, mostly orange-red flowers which are without scales or only slightly scaly at the base and aggregated together into umbels of 10 or more. I have never seen yellow-flowered specimens and this report may be an error although there are occasional purplish-pink-flowered populations which are similar in colour to many of the forms of R. malayanum. A puzzling aspect of this species is the variable shape and size of the flowers. A population in a peat swamp area in southern Sabah had three distinct size classes of flower – large, intermediate and small – which did not appear to intergrade and were all growing together. It is closely related to R. fallacinum, which is maintained in this account although distinguished with difficulty from the complex variation that occurs in R. durionifolium. Rhododendron fallacinum usually has a shorter corolla tube and the flowers are densely scaly outside, with scales occurring right up onto the backs of the corolla lobes. Slender forms of ssp. sabahense approach R. malayanum in form but the petioles do not get quite as long as in that species, the flowers are more numerous from a single flower bud and R. durionifolium never normally produces lateral inflorescences. Rhododendron acuminatum could also be confused but apart from occurring at higher altitude, this species has more strongly puckered leaves with the lateral veins deeply impressed on the upper side and like R. malayanum it has much longer petioles than R. durionifolium.

Rhododendron durionifolium subsp. sabahense Argent, A.Lamb & Phillipps

Differing from the type subspecies in the more slender, narrowly elliptic to elliptic leaves, 90–160 x 20–50mm, with a tapering base; longer petioles: 4–7mm; leaves which are greener and more quickly glabrescent above and flowers predominantly pink or red rather than orange in colour.

Altitude: 900-2400m

Notes

Latin – Sabah – the country; ensis – place or origin. Coming or originating from Sabah.

This subspecies occurs above 900m in fairly uniform populations on Mt Lumarku, Mt Lotung and near Long Pasia, in the Sipitang District. With its red or pink flowers and long corolla tubes it would be suitable for bird pollin­ation but this has not been observed. The only hybrid seen is with R. micromalayanum on Mt Lumarku and in the Long Pasia region. This subspecies has been cultivated since 1980. It grows slowly but has most attractive flowers.

Nomenclature

Type: A. Phillipps SAN 93169, May 1981. Malaysia, Sabah (Borneo), Sipitang District, Long Pasia Track (SAN).

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Rhododendron eclecteum Balfour f. & Forrest

Shrub, 1 -3(-4.5)m; bark smooth and peeling; young shoots usually sparsely glandular. Leaves obovate-lanceolate (jargonelle-shaped) to elliptic, (4-)6-14.5 x (3-)3.5-5.6cm, 1.9-2.3 x as long as broad, apex rounded, apiculate to retuse, base ± cuneate to rounded, upper surface glabrous, lower surface with epidermis epapillate, glabrous though often with at least some simple straight hairs on either side of the midrib, veins conspicuous; petioles 0.4-3cm, narrowly winged, glabrous or with a few stipitate glands. Inflorescence dense, 6-11-flowered; rhachis 5- 15mm; pedicels 10-25mm, glabrous or sparsely glandular. Calyx 2-15mm, usually cupular, ± glabrous, lobes rounded. Corolla campanulate or widely funnel-campanulate, white or cream to (more usually) deep crimson, with or without purple flecks, (30-)40-50mm. Ovary densely stipitate-glandular; style glabrous. Capsule 15-25 x 6-10mm, often glaucous.

Habitat: Bouldery slopes, thickets, cane brakes

Distribution: China (SE Xizang, NW Yunnan, SW Sichuan), ne Upper Burma.

Altitude: 3000-4000m

Notes

R. eclecteum hybridises with R. pocophorum (see under R. x hemigynum). Kingdon-Ward 6900, with leaves typical of R. eclecteum except that they have a floccose but persistent indumentum, may also be of hybrid origin.

Flags

Occurs in Countries: CN, MM Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: cream, crimson, magenta, purple, rose, white, yellow

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):425

Rhododendron eclecteum var. bellatulum [Balfour f. ex] Tagg

Petioles 8-30mm; leaf lamina 6-12.5 x as long as petioles, usually lacking simple hairs; corolla usually white to yellow, sometimes flushed with rose

Notes

Flowering specimens with relatively long petioles and elliptic leaves almost always have pale flowers but well over half the specimens seen lack flowers or flower colour notes. Therefore, the status of var. bellatulum, which apparently intergrades with var. eclecteum, will remain uncertain until field studies are carried out.

Nomenclature

Type: China, Yunnan, Londre Pass, Mekong/ Salween divide, 12000ft, vi 1921, Forrest 19535 (holo. E)

Rhododendron eclecteum var. eclecteum

Petioles 4-10mm; leaf lamina 11-18 x as long as petioles, at least some simple straight hairs usually present near the midrib; corolla usually deep magenta-rose to crimson

Notes

Cowan & Davidian (loc. cit.) state that var. brachyandrum differs from var. eclecteum in its darker flowers. However, there is no indication of the flower colour of the type of var. eclecteum, or indeed of the majority of the herbarium specimens seen. The type of var. brachyandrum has small flowers, the diagnostic character used by the original authors, although, like Cowan & Davidian, 1 consider that to be of little taxonomic significance. If var. eclecteum is restricted to plants with relatively short petioles and deeply coloured flowers then the following specimens are intermediate between vars. eclecteum and bellatulum: Forrest 18023, 25603; Rock 8748, 8750, 9205, 22222, 22224, 22230, 22661, 22664, 22665.

Nomenclature

Type: China, Yunnan, be 1917, Forrest 14804 (holo. E).

Synonymy: R. brachyandrum Balfour f. & Forrest, Notes R.B.G. Edinb. 13: 32 (1920). Type: China, SE Xizang, Tsarong, Salween/Kiu-chiang divide, vii 1919, Forrest 18943 (holo. E). R. eclecteum Balfour f. & Forrest var. brachyandrum (Balfour f. & Forrest) Cowan & Davidian, Rhododendron Yearbook 6: 169 (1951).

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Rhododendron edanoi Merr. & Quisumb.

Notes

Named after Gregorio Edaño, a Philippine collector employed by the Bureau of Science, Manila.

Nomenclature

Type: Edaño PNH 153, 13 May 1947. Philippines, Palawan, Mt Mantalingahan, Brook’s Point (A, BM, E, K, L, PNH†).

Flags

Occurs in Countries: ID, MY, PH Altitude Ranges: 0 - 1,000m: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Vireya Habit: Tree Fl. Colour: brown

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:160

Rhododendron edanoi subsp. edanoi

Shrub to 40cm. Twigs rounded, densely stellate-scaly; internodes 2–5cm. Leaves 4–6 together in tight pseudowhorls. Blade 25–55 x 15–25mm, elliptic, broadly elliptic or obovate-elliptic; apex obtuse to rounded, often with a pale gland-like spot at the apex; margin entire, narrowly revolute; base broadly tapering to rounded; quickly glabrescent above, densely and sub-persistently scaly beneath. Scales stellate, margin deeply divided; centre very small, each on top of a small persistent epidermal tubercle. Mid-vein impressed above, strongly raised beneath throughout its length; lateral veins 3–6 per side, straight, slightly impressed above, obscure beneath; reticu­lation not visible. Petiole 5–7 x c.1.5mm, grooved above, densely scaly. Flower buds to 15 x 8mm, slender, ovoid. Bracts broadly subulate with the upper sides rolled and the tips reflexed, green, with a few scales outside and densely scaly along the margins. Bracts to 15 x 7mm, ovate to elliptic to spathulate, densely scaly outside in the upper 1⁄3, glabrous elsewhere. Bracteoles to 15mm, linear to sub-spathulate. Inflorescence 7–15-flowered, an open umbel, flowers white, horizontal to half-hanging, scented. Pedicels 9–15 x c.1mm, densely stellate-scaly and laxly shortly hairy. Calyx disc-like, oblique, sometimes obscurely 5-lobed. Corolla trumpet-shaped, 30–50 x 25–30mm; tube 25–42 x 6–7 x 4–5mm, straight or slightly curved, densely silvery-scaly outside, (the scales turning brown on drying), laxly hairy inside in the proximal 1⁄3, glabrous distally; lobes 14–16 x 9–11mm, spreading to reflexed, with a few scales outside. Stamens irregularly arranged, at different heights well below the mouth of the tube; filaments 24–30mm, linear, sub-densely hairy at the base only, glabrous distally; anthers c.1.5–2.5 x 1mm, oblong, the bases with small points. Disc densely hairy. Ovary 5–6 x 2–2.5mm, cylindrical, densely scaly and shortly hairy, abruptly tapering distally; style c.25mm, becoming exserted up to 7mm, hairy and scaly in the proximal 1⁄3, laxly hairy in the middle, glabrous in the distal ½; stigma to 1.5mm in diameter, rounded, white or red. Fruit 30–40 x c.5mm, the valves splitting away from the base or apex and often spirally twisting, the placentae becoming slightly separated curving outwards. Seeds 3.5mm, without tails 0.9mm, the longest tail 1.5mm.

Habitat: In mossy sub-montane forest.

Distribution: Philippines, Palawan, Mt Mantalingajan, Thumb Peak, Cleopatra Needle

Altitude: 1500-1725m

Rhododendron edanoi subsp. pneumonanthum (Sleumer) Argent

Shrub or small tree to 3m. Scales blackish-brown. Lateral veins 5–9 per side, straight or curving away from the mid-vein and disappearing before the edge of the leaf, hardly raised but usually distinct both above and below and without visible reticulation. Petiole 1–3 x 3–4mm, dark red, often broader than long and with dark-brown scales, weakly grooved above.

Habitat: Epiphytic in montane mossy forest.

Distribution: Malaysia (Borneo), Sarawak, Mt Lemakok, Mt Lawai, Mt Murut, Mt Murud. Sabah, vicinity of Long Pasia. Indonesia, Mt Kemul, Mt Batu Ajoh, Kayan R.

Altitude: 700-2400m

Notes

Greek – pneumon – lungs; anthos – flower. Applying to the inflated-looking corolla tubes, but not particularly apt.

Rhododendron pneumonanthum has been reduced to a subspecies of R. edanoi (Argent 2004). Sleumer (1966) distinguished these two species: ‘Corolla tube more or less manifestly and gradually narrowed from the base upwards. Leaves sub-sessile [R. pneumonanthum] vs. Corolla tube equally wide all over or slightly and gradually widened from the base upwards. Leaves distinctly petioled. [R. edanoi]’. An examination of isotypes of the original collection of R. edanoi showed that the first character is not a valid difference. Several corolla tubes exhibit quite definite narrowing from the proximal to the distal ends. The corollas from cultivated plants from both Palawan and Borneo in the fresh state all quite clearly taper from base to mouth. After pressing, the tube can appear to at least look parallel sided. There is a difference in petiole length between Bornean and Philippine materials but again there is a good deal of variation even on one plant and this alone would not support maintaining these plants as different species. There is also a very small difference in the scales on the leaves from the two islands – those from Bornean materials are darker and more variable in size – but both have essentially the same sub-stellate shape, are tall and are set on pronounced epidermal tubercles. The vegetative habit of the plants in cultivation from the different islands is certainly very different. Both Philippine collections are slow and low growing compared with the tall, ‘leggy’ and much more vigorous Bornean plants. Differences in habit between different populations of the same species are known elsewhere (R. burttii and R. leptanthum). The clinching factor in regarding the Bornean R. pneumonanthum to be, at best, a subspecies and not specifically distinct from R. edanoi is the fact that the distinctive flower bud morphology is identical in plants from both Borneo and Palawan.

Nomenclature

Type: Endert 4522, 23 Oct. 1925. SE Borneo, W Kutei, Mt Kemul, c.1700m (L, A, BO, SING).

Synonymy: R. jasminiflorum (non Hook.) Ridl., J. Str. Br. R. As. Soc. 1912. 63: 60. R. pneumonanthum Sleumer, Reinwardtia 1960. 5: 132.

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Rhododendron edgeworthii Hooker

Shrub to 2-5 m, epiphytic or scrambling on rocks. Indumentum dark orange to pale beige brown. Leaves oblong-ovate, oblong-lanceolate or rarely elliptic, 6-15 x 2-5-5 cm, usually acuminate, upper surface strongly bullate and glabrous; scales on the lower surface completely obscured by the indumentum, small, distant, golden. Inflorescence 2-3-flowered, pedicels up to 2 cm, densely tomentose. Flowers usually fragrant. Calyx clearly lobed, the lobes oblong-orbicular, densely tomentose on the margins and also usually on the outer surface, lepidote on the outer surface, the inner surface finely pubescent, 11-14 mm. Corolla funnel-campanulate, (35-)45-60(-66) mm, the tube (19-)25-30(-40) mm, white, sometimes flushed pink and/or with a yellow blotch at the base, glabrous within, lepidote outside. Stamens 10, declinate, filaments densely pilose in the lower part. Ovary densely tomentose. Style about as long as the corolla, declinate, exceeding the stamens, tomentose and/or lepidote for a variable distance above the base. Capsule densely tomentose, oblong-globose, c. 18 x 12 mm.

Habitat: In dense forest.

Distribution: India (Sikkim, W Bengal, Arunachal Pradesh), Bhutan, e Burma, China (N, NW & C Yunnan, S Xizang).

Altitude: 2100-3300m

Illustrations:

Notes

Variable in size and habit across a very wide distribution area; the variation, however, is not amenable to taxonomic recognition.

Nomenclature

Type: Sikkim Himalaya, in valleys on the inner range, 7000-9000 ft, fl. May-June, fr. November, Hooker (K)

Synonymy: R. bullatum Franchet Bull. Soc. Bot. Fr. 34:281 (1887) China, Yunnan, ad pedem montis Tsang-chan, alt. 2500 m, 20 iv 1886, Delavay 2062 (P) R. sciaphilum Balfour f. & Kingdon Ward Notes R.B.G. Edinb. 10:146 (1917) E Burma, Htawjaw, valley of Naung chaung, Lashi country, 7000-8000 ft, 4 vi 1914, Kingdon Ward 1629 (holo. E)

Flags

Occurs in Countries: BT, CN, IN, MM Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: pink, white, yellow

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):26

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Rhododendron elegantulum Tagg & Forrest

Shrub, 1-1.6m. Leaves elliptic-oblong, 7-13 x 2.4-3.5cm, 3-3.7 x as long as broad, apex acute, base rounded, lower surface covered with a dense unistrate ramiform lanate indumentum, deep pink when young, maturing to a rich rufous brown; petioles 1 —1.5cm, tomentose at first, later glabrescent. Inflorescence 10-20-flowered; rhachis 2-3mm; pedicels c.20mm, rufous-tomentose, at least at first. Calyx c.l2mm, stipitate-glandular, lobes oblong, rounded, glandular-ciliate. Corolla campanulate, pale purplish pink, with crimson flecks, 30-4Omm. Ovary densely stipitate-glandular; style with a few glands at base. Capsule c.15 x 5mm.

Habitat: Among conifers, rocky slopes, meadows

Distribution: China (NW Yunnan, SW Sichuan, nr Yungning)

Altitude: 3650-3950m

Notes

Closely allied to R. bureavii and possibly a hybrid between that species and R. adenogynum

Nomenclature

Type: China, SW Sichuan, Yung-ning, 13000ft, 7 v 1922, Kingdon-Ward5U (holo. E).

Flags

Occurs in Countries: CN Altitude Ranges: 3,000 - 4,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: crimson, pink

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):339

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Rhododendron elliottii Watt in Brandis

Small straggling shrub; young shoots stellate-tomentose and stipitate-glandular. Leaves lanceolate to elliptic, 8.5-10 x 3.5-4.2cm,c.2.5 x aslongas broad, apex rounded, apiculate, base rounded, glabrous when mature on both surfaces; petioles 1.5-2.5cm, glabrous. Inflorescence 6—10-flowered; rhachis c.20mm; pedicels c.lOmm, shortly stipitate-glandular. Calyx 3—4mm, glandular, lobes rounded, glandular-ciliate. Corolla funnel-campanulate, rose-purple, with darker flecks, 40-50mm. Ovary densely rufous stellate-tomentose, intermixed with stipitate glands; style tomentose and glandular to tip. Capsule c.15 x 5-6mm.

Distribution: NE India (Nagaland)

Altitude: 2700-3000m

Illustrations:

Notes

Allied to R. kyawi and R. facetum but differing from both in its generally smaller leaves and apparently in the shape of the corolla.

Nomenclature

Type: NE India, Manipur, Japoo, 9000ft, v 1882, Watt 6893 (holo. K; iso. E).

Flags

Occurs in Countries: IN Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: rose

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):379

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Rhododendron emarginatum Hemsl. & E.H.Wilson

Shrub to 2m. Twigs 1–2mm in diameter, green, with stalked scales, conspicuously rough with the persistent protruding scale bases; internodes 1–4cm. Leaves 4–7 together in tight pseudowhorls. Blade 12–40 x 5–25mm, broadly elliptic to obovate; apex emarginate or rounded, with a small protruding mucronate gland; margin entire, slightly revolute; base narrowly tapering; upper surface green, glabrescent, lower surface sparsely covered with scales, pale green. Scales sub-circular, brown or translucent, mostly pale, variable in size and slightly impressed. Mid-vein impressed above and raised beneath, lateral veins 2–4 per side, weakly impressed above and raised beneath or obscure in smaller leaves. Petiole 2–4mm, grooved above, rounded below, brown scaly and very shortly hairy above. Flower buds 6–8 x 3–4mm, green becoming pale brown, ovate, smooth with broadly acute points. Bracts minutely shortly hairy outside and fringed with longer white hairs, glabrous inside. Bracteoles 1.5mm, filiform with a few white hairs, withering quickly. Pedicels 15–25 x c.1mm, green, moderately to densely scaly from an uneven surface. Inflorescence of solitary, or paired, flowers, semi-erect, horizontal to half-hanging. Flowers 6–8 x 16–22mm, campanulate. Calyx green, densely scaly, wavy to distinctly lobed with rounded or weakly triangular lobes to 3mm. Corolla yellow; tube 4–5 x 4–5 x 4–5mm, moderately densely scaly outside with inconspicuous translucent scales, and with long patent white hairs just below the mouth inside; lobes 6–8 x 5–7mm, the three upper patterned with rows of faint orange-brown spots on the inner side and with a few translucent scales outside, reflexed to the horizontal or a little beyond, overlapping up to 1⁄3. Stamens arranged all round the mouth but with a gap on the lower side where the style is placed, irregularly dimorphic and exserted to 5mm; filaments yellow, tapering to the base in the lower 1⁄3 and also upwards for about 2⁄3, with long patent white hairs in the middle part; anthers 2–2.5 x c.1mm, brown. Disc green, glabrous. Ovary 2.8 x 2.2mm, green, densely covered in silvery scales. Fruit 12–16 x 4–5mm, the pedicel turning to place them erect, green passing to brown, cylindrical with longitudinal grooves and a persistent deflexed style; valves splitting to the base and curving backwards, straight, not twisting, the placentae remaining firmly adherent to the central column. Seeds 4–4.7mm, bright orange-brown, without tails 1.2–1.9mm, the longest tail 1.2–1.5mm, tails mostly straight, sometimes a little crimped usually at just one end.

Habitat: In tropical monsoon forests, often epiphytic on branches of trees

Distribution: China, SE Yunnan, Pingbian, Xichou, Malipo and Mengzi. Guangxi, Daimiaoshan Xian, Pingshixiang, Jiuwandai shan. Vietnam, Province Lao Cai.

Altitude: 1200-2900m

Notes

Latin – emarginatus – shallowly notched, alluding to the often emarginate tips to the leaves.

Professor Sleumer compared the types of R. euonymifolium and R. poilanei (Sleumer 1958) and reduced these species to synonymy. These types have also been examined for the present study and their reduction appears logical. Rhododendron leiboense was differentiated in having more slender branches, triangular calyx lobes and flowers in twos. It does not appear to warrant even varietal recognition on these characters. I have reduced R. maguanense after examining the type material. Feng (1983) said this species was close to R. emarginatum but differentiated it on its smaller leaves and longer calyx lobes. Neither of these characters are sufficiently significant. The calyx lobe development is considered variable in R. emarginatum and the smaller leaves with less conspicuous venation appear to be reduction due to exposure.

Nomenclature

Type: Henry 9166. China, Yunnan, Mountains SW of Mengtsze (K)

Synonymy: R. euonymifolium H.Lév., Fedde Rep. 1913. 12: 228. R. poilanei Dop, Fl. Gén. I.-C. 1930. 3: 739. R. maguanense K.M.Feng, Acta Bot. Yunnan. 1983. 5(3): 268. R. leiboense Z.J.Zhao, Bull. Bot. Research 1987. 7(3): 57, f.1, 63.

Flags

Occurs in Countries: CN Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Vireya Habit: Epiphyte, Non-Tree Fl. Colour: orange, white

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:31

Rhododendron emarginatum var. eriocarpum K.M.Feng

Differing chiefly in that the ovary is both hairy and scaly. The calyx lobes are also well developed, 1.8 x 2mm, with scales along the margins of the lobes. Seeds 2.5–3mm, without tails c.1mm, the longest tail 1.2mm.

Distribution: Known from the type locality in China and Guangxi Province, Daimiaoshan Xian, Pingshixiang, Jiuwandai shan

Altitude: 1200-2180m

Notes

Greek – erio – woolly; carpon – fruit. Alluding to the hairy ovary.

Recorded flowering in Aug. and Oct. The hairy ovary is one of the significant characters separating R. emarginatum from R. insculptum. This variety confuses this distinction.

The leaves of var. eriocarpum are quite distinct in being less revolute and more distinctly tapering towards the base than those of R. emarginatum. It might yet warrant specific status.

Nomenclature

Type: K.M. Feng 4852, 10 Oct. 1954. China, Yunnan, Pingbian Xian, Daiweishan (KUN)

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Rhododendron englerianum Koord.

Shrub to 1.2m. Twigs 5–7mm in diameter, rounded, scaly at first, quickly becoming glabrescent; internodes 4–10cm. Leaves 3–4 together in pseudowhorls, large, sub-sessile. Blade 120–250 x 40–90mm, elliptic, or sub-ovate-elliptic; apex short to long-acuminate, acute or sub-acute; margin narrowly but very distinctly revolute; base broadly tapering, the extreme base truncate-rounded or slightly cordate, glabrescent above when mature, laxly scaly beneath. Scales small, marginal zone irregularly and shallowly lobed; centre slightly impressed. Mid-vein narrow and markedly impressed above, strongly prominent on the underside proximally; lateral veins 8–14 per side, with additional shorter ones between, irregular and ascending, arching inwards before the margin, slightly raised above, more distinctly so beneath, reticulation lax, slightly raised on both sides. Petiole 4–7 x 3–4mm, grooved above, densely scaly. Bracts to 55 x 15mm; outer bracts ovate-lanceolate, long acute hairy and scaly outside; inner ones broadly ovate-acuminate and sub-acute to elliptic-spathulate, also hairy and scaly, glabrous inside. Bracteoles to 30 x 1mm, linear-filiform, scaly and hairy. Inflorescence 4–9-flowered, an open umbel. Pedicels 60–110 x c.1.5mm, erect, laxly scaly, minutely and sparsely hairy. Calyx c.5mm in diameter, rounded or very shortly, obtusely 5-lobed, scaly outside. Corolla c.80 x 100mm, funnel-shaped, orange or reddish to pink, flushed yellow outside; tube 25–30 x 5–8 x 15–20mm, lobed at the base, laxly stellate-scaly outside, laxly hairy inside, with prominent dark veins running lengthwise to the apices of the lobes in the dry state; lobes 50–60 x 30mm, obovate, spreading. Stamens exserted to 25mm; filaments linear and densely hairy in the proximal ½, filiform and glabrous distally; anthers 6–7 x 1mm, linear-oblong, slightly curved. Disc prominent, hairy in the upper ½, glabrous below. Ovary 9–10 x c.3mm, sub-cylindrical, hairy, with numerous minute brown scales between the hairs, tapering gradually distally; style as long as the stamens and covered with short hairs and clearly visible scales in the proximal ½–2⁄3; stigma thick, 5-lobed. Fruit 60–100 x c.5mm, elongate-cylindrical, laxly hairy and scaly.

Habitat: Epiphytic in Agathis forest, or terrestrial in rain forest, 400–600m, also reported from rocks near a river, 1220–2745m.

Distribution: Indonesia, New Guinea (W), Noord R.; Vogelkop, Dalman, near Nabire. Papua New Guinea, Central District, Musgrave Range; Mt Yule.

Altitude: 400-2745m

Notes

Named after Victor G.A. Engler (1885–1917).

Very similar to R. baenitzianum but apparently distinct in the clearly revolute margin to the leaf and longer petioles. Baron von Mueller used the invalid name ‘megalo­stigma’ for this species which has extremely divided stigmatic lobes.

Nomenclature

Type: Versteeg 1632, 3 July 1907. New Guinea (SW), Noord R., Bivak, Alkmaar (BO, K, L, U).

Flags

Occurs in Countries: ID, PG Altitude Ranges: 0 - 1,000m: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Vireya Habit: Epiphyte, Non-Tree

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:318

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Rhododendron erastum Balfour f. & Forrest

Dwarf shrub, 0.05-0.5m; young shoots ± densely rufous floccose-tomentose; perulae apparently ± persistent. Leaves elliptic to narrowly elliptic, 2.5-4.7 x 0.7-1.7cm, 2.6-5 x as long as broad, apex rounded, apiculate, base ± rounded, upper surface ± glabrous when mature, lower surface purple or green, with the remnants of a floccose ramiform tomentum and often a few stipitate glands, especially on the midrib; petioles c.0.5cm, floccose-tomentose. Inflorescence 1 -3-flowered; rhachis minute; pedicels c. 10mm, sparsely tomentose. Calyx c. 1.5mm, fleshy, ± floccose. Corolla tubular-campanulate, rose-pink, 25-30mm. Ovary with a whitish to rufous tomentum intermixed with stipitate glands. Capsule not known.

Habitat: Rocky meadows

Distribution: China (SE Xizang, NW Yunnan)

Altitude: 3950-4250m

Notes

Allied to R. chamaethomsonii and R. forrestii and possibly of hybrid origin. Intermediates between R. chamaethomsonii and R. erastum are as follows: Forrest 16700, 17444, 19491, 20032.

Nomenclature

Type: China, W NW Yunnan, Mekong/Salween divide, 28°12'N, 14000ft, vii 1917, Forrest 14373 (holo. E; iso. K)

Synonymy: R. porphyrophyllum Balfour f. & Forrest, Notes R.B.G. Edinb. 11: 108 (1919). Type: China, SE Xizang, Tsarong, on Ka-gwr-pw, 13000ft, vi 1918, Forrest 16695 (holo. E). R. serpens Balfour f. & Forrest, ibid. 11: 135 (1919). Type: China, SE Xizang, Tsarong, on the northern slopes of Ka-gwr-pw, 14000ft, vii 1918, Forrest 16698 (holo. E).

Flags

Occurs in Countries: CN Altitude Ranges: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: rose

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):405

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Rhododendron ericoides Low ex Hook.f.

Erect wiry shrub, to 1.5m, dwarfed at its highest localities. Twigs densely leafy, scaly and sometimes minutely hairy on the youngest growth. Stems with protruding leaf-cushions in the younger parts. Leaves spirally and evenly arranged, very dense and imbricate in the upper part of the twigs and held sub-erect. Blade 4–8 x 0.8–1.6mm, ‘ericoid’, linear or very narrowly elliptic; apex acute (with the extreme point rounded), with an obtuse glandular point; margin entire or somewhat indented with irregular crenulations, somewhat thickened and slightly or not revolute; base tapering, glabrescent above, laxly scaly beneath. Scales disc-shaped, entire with the darker centre thick and slightly impressed. Mid-vein very slightly impressed above, swollen underneath; lateral veins obscure. Petiole 0.6–1 x 0.4–0.6mm, scaly and with a few simple hairs, minutely grooved above and with a swollen, bulbous base. Flower buds to 3.5 x 2.5mm, pink, scaly outside. Bracts all appressed, the outermost subulate, inner ovate, scaly in the upper ½ outside, all with a ciliate margin of white hairs. Inflorescence of solitary flowers or paired, rarely up to 4 in an umbel, hanging vertically. Bracteoles c.3 x 0.5mm, linear-spathulate, long-ciliate upwards, falling early. Pedicels 5–8mm, slender, densely scaly, without hairs. Calyx slightly oblique, scaly outside, glabrous inside, with 5 distinct erect lobes, c.2 x 1–1.3mm, initially appressed to the corolla, later spreading, narrowly sub-ovate-triangular, obtuse. Corolla bright red, tubular, not or slightly oblique and curved, c.15 x 11mm; tube c.11 x 6 x 7mm, densely scaly outside, glabrous inside; lobes c.4 x 5mm, scaly outside except near the margins, broadly ovate to rounded, half-spreading and overlapping to c.halfway, the margins irregularly denticulate. Stamens grouped on the lower side of the flower, slightly exserted to c.1mm; filaments glabrous, c.11mm; anthers brown, c.0.9mm. Disc glabrous. Ovary c.1.8mm, conical, green, densely scaly, gradually tapering distally; style red, to 14mm, glabrous, finally exserted, to c.3mm; stigma club-shaped. Fruit oblong-ovoid, often a little oblique and curved, 7–10 x 3–4mm. Seeds 1.5–2mm, without tails 0.75mm, the longest tail to 0.5mm, the tails often with multiple points.

Habitat: In primary mossy forest, abundant terrestrially on the open granite dome in exposed sunny places

Distribution: Malaysia (Borneo), Sabah, Mt Kinabalu, endemic (records from other mountains are all referable to R. borneense).

Altitude: 2700-4000m

Notes

Greek – Erica – a genus of mainly South African shrubs; oides – indicating resemblance, the small leaves of this species being very like those of an Erica.

Flower and fruit Jan.–Dec.

Rhododendron x silvicola Sleumer (R. cuneifolium x R. ericoides) Rhododendrons of Sabah, Sabah Parks Publ. 1988. 8: 102. Type: J. & M.S. Clemens 30081, April–June 1932. Borneo, North Borneo, Mt Kinabalu, Tenompok, 5000ft (E, K). Derivation: Latin – silva – wood or forest; cola – inhabitant. An inhabitant of the forest since it was first thought to be a shade form of R. ericoides. Synonyms: R. ericoides var. silvicolum Sleumer, Reinwardtia 1960. 5: 62 (orthographic variant). R. x silvicolum Sleumer, Rhododendrons of Sabah 1988: 102 (orthographic variant). Shrub to 3m. Similar to R. ericoides but with larger leaves, 9–11 x 1.8–2mm, flowers red, usually with elong­ate calyx lobes. Malaysia (Borneo), Sabah. Fairly common on Mt Kinabalu around the zone of overlap between the two parent species. Recent records are all between 2800 and 3200m although the type collection was recorded at 1525m – this is possibly an error. A large shrub of this hybrid has persisted over more than 20 years beside the main trail up Kinabalu where it is very conspicuous.

Nomenclature

Type: Low s.n., March 1851. Borneo, North Borneo, Mt Kinabalu (CGE, K).

Flags

Occurs in Countries: MY Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Vireya Habit: Non-Tree Fl. Colour: red

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:48

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Rhododendron eriocarpum (Hayata) Nakai

Habitat: Thickets, open woodland

Distribution: Japan (Kyushyu, Ryukyu Islands)

Altitude: Around 300m

Illustrations:

Notes

Contrary to Ohwi's most recent statement in the new edition of his Flora of Japan, we are convinced that R. tamurae is a synonym of R. eriocarpum. R. tawadae is described as having small reddish-purple flowers; this agrees better with R. eriocarpum than it does with R. simsii, with which it has been synonymized in the past.

Nomenclature

Type: Japan, Liukiu, Nakanoshima, 2 viii 1910, Hayata 96 (holo. TI).

Synonymy: R. indicum Sweet var. eriocarpum Hayata, Icon. PI. Formosan. 3: 134(1913). R. indicum Sweet var. tamurai [sphalm. pro tamurae] Makino in Bot. Mag. Tokyo 18: 102,103, L (1904); R. tamurae (Makino) Masamune, Prelim. Rep. Veg. Yakus. 106 (1929) & Mem. Sci. Agric. Taihoku Imp. Univ. Bot. 11(4): 349 (1934). Type: Japan, Tokyo, cult., vi 1904, Makino, n.v. R. eriocarpum (Hayata) Nakai var. tawadae Ohwi in Bull. Nat. Sci. Mus. Tokyo n.s. 1: 4 (1954); R. tawadae (Ohwi) Ohwi. J. Jap. Bot. 29: 369 (1954). Type: Japan, Ryukyu, vertice Ivi. Uwotsuridake ins. Uwotsuri, 300-320m, 17 iv 1953, Tawada 29, n.v.

Flags

Occurs in Countries: JP Altitude Ranges: 0 - 1,000m Subgenus: Tsutsusi

Chamberlain, D.F. & Rae, S.J. (1990) A Revision of Rhododendron IV Subgenus Tsutsusi. Edinburgh Journal of Botany 47(2):118

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Rhododendron erosipetalum J.J.Sm.

Erect or spreading shrub to 2m. Twigs densely covered with stalked scales, the lower parts rough where the scales have gone and the stalks remain. Leaves spiral, often somewhat crowded in the upper part of the twigs. Blade 6–13 x 2–4mm, narrowly obovate; apex obtuse or mostly rounded, often slightly retuse; margin revolute; base gradually tapering, dark green above, paler beneath, glabrescent above, laxly scaly beneath. Scales circular, their marginal zone narrow, entire; centre darker, thick, slightly impressed. Mid-vein slightly or not impressed above, raised beneath; lateral veins not visible. Petiole 1–1.5mm. Bracts to 4 x 3mm, ovate, apiculate, hairy and laxly scaly outside, shortly white-ciliate on the margins. Bract­eoles to 5mm, filiform. Inflorescence of solitary flowers, hanging vertically. Pedicels 8–10mm, laxly to sub-densely covered with scales and minute white, patent hairs. Calyx small, disc-like, 5-angular or shortly obtusely 5-lobed, scaly. Corolla c.20 x 10mm, tubular, somewhat curved and a little compressed laterally, deep pink to dark red; tube 15–18 x 3–4 x 5–6mm, laxly scaly outside, glabrous inside; lobes c.3–4 x c.3mm, unequal, minutely hairy distally outside, ovate or ovate-elliptic, the apex rounded and minutely irregularly denticulate. Stamens unequal, some slightly exserted from the corolla; filaments narrowly linear, glabrous; anthers c.1.2mm. Disc glabrous. Ovary c.3mm, obliquely conical, longitudinally 5-grooved, densely scaly, tapering distally; style c.13mm, glabrous, somewhat thickened distally to the club-shaped irregularly lobed stigma. Fruit 8–15 x c.3mm, sub-cylindrical, deeply 5-grooved. Seeds 0.15–2mm, shortly tailed at both ends.

Distribution: Indonesia, New Guinea (W), Vogelkop Peninsula, Arfak Mts, Tohkiri, Tamrau and Nettoti Range. Epiphytic or terrestrial, rare on a burnt open summit, mostly on the edge of moss forest, or summit scrub on peaty soil

Altitude: 1400-2650m

Notes

Latin – erosus – having an irregular apparently gnawed margin; petalum – of the petals. The corolla lobes having an erose, or raggedly irregular, margin.

Nomenclature

Type: Mayr 18, 27 May 1928. New Guinea (W), Arfak Mts, 1800m (BO, lectotype, L, fragment).

Flags

Occurs in Countries: ID Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Vireya Habit: Non-Tree

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:57

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Rhododendron erosum Cowan

Tree, 3.5-6.5m; young shoots with numerous gland-tipped setae. Leaves broadly obovate, 8—10 x 3.7—7cm, 1.5—2.1 x as long as broad, apex and base rounded, upper surface glabrous, lower surface with sparse stout gland-tipped setae and a floccose lanate indumentum, dense at first, becoming thinner with age, midrib with a few bristles; petioles clem, sparsely glandular-bristly. Inflorescence dense, 12-15-flowered; rhachis c.lOmm; pedicels c.lOmm, stipitate-glandular. Calyx reddish, 3-4mm, glabrous, lobes rounded. Corolla tubular-campanulate, rose-pink to crimson, 30-35mm. Ovary densely stipitate-glandular; style glabrous. Capsule c.20 x 6mm, curved.

Habitat: Under Abies, etc.

Distribution: China (SE Xizang)

Altitude: 3000-3800m

Notes

Closely allied to R. exasperatum but differing in several minor characters; possibly of hybrid origin.

Nomenclature

Type: China, S Xizang, Chayul Chu, Natrampa, Kashong La, 12500ft, 2 v 1936, Ludlow & Sherriff1541 (holo. BM; iso. E).

Flags

Occurs in Countries: CN Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Hymenanthes Habit: Tree Fl. Colour: crimson, rose

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):382

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Rhododendron esetulosum Balfour f. & Forrest

Shrub, 1.5-2m; young shoots glabrous or with minute stipitate glands. Leaves coriaceous, ovate to elliptic, 6-12 x 3-4cm, 2(-3) x as long as broad, apex rounded, apicuiate, base + cordate, upper surface glabrous, lower surface with a thin scattered adpressed indumentum, even when mature; petioles l-2cm, glabrous when mature. Inflorescence 8-10-flowered; rhachis less than 5mm; pedicels 15-30(-40)mm, densely stipitate-glandular. Calyx (1-) 4-10mm, lobes broadly ovate and rounded when well-developed, stipitate-glandular. Corolla funnel-campanulate, white flushed rose, with or without purple flecks, 30-35mm. Ovary densely stipitate-glandular, style glandular, at least at base. Capsule c. 20 x 10mm.

Habitat: Thicket margins, bouldcry slopes

Distribution: China (NW Yunnan, SE Xizang)

Altitude: 3000-4250m

Notes

The large coriaceous leaves distinguish this species from the remaining members of subsection Selensia. The length of the calyx lobes is variable, even within a single gathering (cf. Rock 11094).

Nomenclature

Type: China, E NW Yunnan, Mts NE of Chungtien, vii 1918, Forrest 16581 (holo. E; iso. K)

Synonymy: R. manopeplum Balfour f. & Forrest, Notes R.B.G. Edinb. 13: 275 (1922). Type: China, SE Xizang, Tsarong Province, duplicate of Forrest no.?, 1919, Forrest 18654 (holo. E; iso. K).

Flags

Occurs in Countries: CN Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: purple, rose, white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):281

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Rhododendron esquirolii Leveille

Shrub, young branches glabrous. Leaves glabrous; blade elliptic-lanceolate, 35-100 x 12-18 mm, base cuneate, apex acuminate, coriaceous; petiole c.6 mm long. Inflorescence buds lateral, clustered at the ends of leafy shoots, 1-2-flowered; bud scales glabrous and shining on their backs, margins of the upper scales ciliate; pedicels c. 12 mm long, glabrous. Calyx of 5 triangular or sometimes linear, lobes, glabrous. Corolla small (c.25 mm long) with a relatively long tube (c.l2mm long), glabrous. Stamens 10, filaments almost glabrous. Ovary cylindric, c.5mm long, glabrous; style glabrous. Capsule not seen.

Distribution: China (Guizhou)

Notes

A rare species, the only specimens seen being those collected by Esquirol and Cavalerie. It has the smallest flowers and the smallest average leaf size of any species of the section. It falls within the group combining glabrous pedicels with (mainly) 1-flowered inflorescences.

Nomenclature

Type: China, Guizhou, vi 1905, Esquirol 476 (holo. E).

Synonymy: R. vaniotii Leveille, Feddes Repert. 13:148 (1914). Type: China, Guizhou, Gan-chuan, iv 1912, Cavalerie 3886 (holo. E).

Flags

Occurs in Countries: CN Subgenus: Azaleastrum Habit: Non-Tree

Philipson, W.R. & Philipson, M.N. (1986) A Revision of Rhododendron III. Subgenera Azaleastrum, Mumeazalea, Candidastrum and Therorhodion. Notes from the Royal Botanic Garden Edinburgh 44(1):10

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Rhododendron euchroum Balfour f. & Kingdon-Ward

Dwarf shrub, up to 0.7m; young shoots floccose-tomentose and stipitate-glandular. Leaves oblanceolate to elliptic, 4.5-7.5 x 1.7-2.3 cm, 2.7-3.3 x as long as broad, apex rounded, minutely apiculate, base ± rounded to cuneate, upper surface glabrous, lower surface with a bistrate indumentum, the upper layer fulvous, ramiform-tomentose, the lower adpressed, whitish, epidermis epapillate; petioles 0.5—lcm, narrowly winged, setulose-glandular, also sparsely floccose-tomentose. Inflorescence 4—5-flowered; rhachis minute; pedicels 7—10mm, densely stipitate-glandular and floccose-tomentose. Calyx 1—2mm, lobes rounded, glandular and tomentose. Corolla fleshy, tubular-campanulate, bright brick-red to scarlet, 25-30mm. Ovary densely stipitate-glandular and stellate-tomentose, tapering into the style which is sparsely tomentose below. Capsule not known.

Habitat: Undershrub in thickets

Distribution: NE Upper Burma

Altitude: 3000-3400m

Notes

Apparently allied to R. albertsenianum on account of its bistrate indumentum but differing in its glandular indumentum and smaller leaves.

Nomenclature

Type: E Upper Burma, Mwai divide, ridge of Naung-Chaung, 10000ft, 14 vii 1914, Kingdon-Ward 1778 (holo. E; iso. K).

Flags

Occurs in Countries: MM Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: brick, scarlet

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):413

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Rhododendron eudoxum Balfour f. & Forrest

Dwarf shrub, 0.3—1.2m; young shoots tomentose, usually also with a few weak setae, rarely ± densely and strongly setose. Leaves elliptic, 3.5-9 x 1—3cm, 2.8—3.5 x as long as broad, apex rounded, apiculate, base rounded, upper surface glabrous, lower surfaces with a thin discontinuous, whitish to brown indumentum and a greenish epapillate epidermis; petioles 0.5-l(—1.5)cm, usually tomentose, sometimes also weakly setose. Inflorescence 2—6-flowered; rhachis c.5mm; pedicels 10-20mm, tomentose, sometimes also glandular. Calyx 2-7mm, cupular when well-developed, lobes rounded, very sparsely tomentose or glandular. Corolla not fleshy (perhaps so in var. mesopolium), tubular-campanulate to campanulate, pink to rose-carmine, 25—40mm. Ovary predominantly glandular to predominantly tomentose. Capsule 15-20 x c.5mm.

Habitat: Cliffs, rocky slopes, thickets, etc.

Distribution: China (border of SE Xizang & NW Yunnan)

Altitude: 3350-4250m

Notes

The distinction between var. brunneifolium and var. mesopolium, as implied by the key, is of a fairly trivial nature but, despite this, var. mesopolium may be more distantly allied to var. brunneifolium and var. eudoxum than these two are to one another. Although it cannot be confirmed for certain from herbarium material, the corollas of var. mesopolium do appear to have been more fleshy and more obviously tubular-campanulate than those of the other two varieties. In these respects var. mesopolium is apparently closer to R. sanguineum and its allies.

The following sterile specimens are referable to R. eudoxum s.L: Forrest 14762, 17334, 17336, 20052, 22700.

Flags

Occurs in Countries: CN Altitude Ranges: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: magenta, rose, white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):401

Rhododendron eudoxum var. brunneifolium (Balfour f. & Forrest) Chamberlain

Notes

Young shoots and pedicels tomentose, with a few weak glandular setae; leaves 7—9cm, with a thin floccose brownish indumentum beneath, not papillate. Inflorescence lax, corolla c.40mm, rose-carmine. Ovary tomentose, eglandular.

Nomenclature

Synonymy: R. brunneifolium Balfour f. & Forrest, Notes R.B.G. Edinb. 13: 33 (1920). Type: China, SE Xizang, Tsarong, Kiu-chiang divide, vii 1919, Forrest 19025 (holo. E; iso. K). R. eudoxum Balfour f. & Forrest subsp. brunneifolium (Balfour f. & Forrest) Tagg in Stevenson (ed.), The Species of Rhododendron 549 (1930).

Rhododendron eudoxum var. eudoxum

Young shoots and pedicels tomentose, usually also with a few weak glandular setae. Leaves 3.5-7(-8.5)cm, with a thin brownish discontinuous indumentum beneath. Inflorescence lax. Corolla 30(-37)mm, rose-pink to magenta, rarely white. Ovary predominantly stipitate-glandular.

Notes

R. fulvastrum var. albipetalum is apparently no more than an albino form of var. eudoxum. The young shoots of the types of both R. trichomiscum and R. trichophlebium are ± densely covered with stout setae as in R. temenium but otherwise are closer to R. eudoxum.

Nomenclature

Type: China, NW Yunnan, Mekong/Salween divide, 28°12'N, 11000ft, vii 1917, Forrest 14245 (holo. E; iso. K)

Synonymy: R. trichomiscum Balfour f. Forrest, ibid. 12: A69 (1920). Type: China, SE Xizang, Tsarong, Ka-gwr-pw, 14000ft, 28°24;N, vii 1918, Forrest 16826 (holo. E; iso. K). R. trichophlebium Balfour f. & Forrest, Notes R.B.G. Edinb. 13: 62 (1920). Type: China, SE Xizang, Tsarong, (1917), Forrest 18632 (holo. E). R. eudoxum Balfour f. & Forrest subsp. trichomiscum (Balfour f. & Forrest) Tagg in Stevenson (ed.), The Species of Rhododendron 549 (1930). R. fulvastrum Balfour f. & Forrest subsp. trichomiscum (Balfour f. & Forrest) Cowan and subsp. trichophlebium (Balfour f. & Forrest) Cowan, Notes R.B.G. Edinb. 20: 79 (1940). R. temenium Balfour f. & Forrest subsp. albipetalum Cowan, ibid. 20: 83 (1940). Type: China, SE Xizang, Tsarong, Solo-la, 13000ft, v-vi 1932, Rock 22295 (holo. E). R. temenium Balfour f. & Forrest subsp. rhodanthum Cowan, ibid. 20: 83 (1940). Type: China, NW Yunnan, Mts of Londre, Mekong/Salween divide, 1923, Rock 10285 (holo. E).

Rhododendron eudoxum var. mesopolium (Balfour f. & Forrest) Chamberlain

Young shoots and pedicels usually floccose-tomentose, eglandular, not strongly setose; leaves 3.5-7cm, with ± prominent veins and a thin whitish discontinuous indumentum beneath; corolla 30-35mm, rose-pink; ovary predominantly tomentose though sometimes also with a few glands.

Nomenclature

Synonymy: R. mesopolium Balfour f. & Forrest, Notes R.B.G. Edinb. 13: 57 (1920). Type: China, SE Xizang, Tsarong, Dokar La, 13- 14000ft, vii— viii 1918, Forrest 16751 (holo. E; iso. K). R. asteium Balfour f. & Forrest, ibid. 13: 235 (1922). Type: China, SE Xizang, Tsarong, Salween/Kiu-chiang divide, 28°40'N, 98°15'E, vii 1919, Forrest 18937 (holo. E; iso. K). R. epipastum Balfour f. & Forrest, ibid. 13: 258 (1922). Type: China, SE Xizang, Tsarong, 1919, Forrest 18645 (holo. E; iso. K). R. eudoxum Balfour f. & Forrest subsp. asteium (Balfour f. & Forrest) Tagg, subsp. epipastum (Balfour f. & Forrest) Tagg and subsp. mesopolium (Balfour f. & Forrest) Tagg in Stevenson (ed.), The Species of Rhododendron 549 (1930). R. fulvastrum Balfour f. & Forrest subsp. mesopolium (Balfour f. & Forrest) Cowan & subsp. epipastum (Balfour f. & Forrest) Cowan, Notes R.B.G. Edinb. 20: 79-80 (1940).

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Rhododendron eurysiphon Tagg & Forrest

Shrub, 1-1.8m; young shoots minutely stipitate-glandular. Leaves 3.5-5.5 x 1.8-2.lcm, 2-2.5 x as long as broad, apex rounded, apiculate, base rounded, upper and lower surfaces glabrous, epidermis epapillate, glaucous beneath; petioles 0.5-0.7cm, glabrous to stipitate-glandular at maturity. Inflorescence 1-3-flowered, lax; rhachis c.3mm; pedicels 12-20mm, sparsely stipitate-glandular. Calyx c.3mm, sparsely stipitate-glandular. Corolla campanulate, creamy white flushed pale rose, with conspicuous flecks, 30-40mm. Ovary and most of style densely stipitate-glandular. Capsule 13-18 x c.6mm, curved.

Habitat: Thickets, etc.

Distribution: China (SE Xizang)

Altitude: Around 4000m

Notes

This species has been traditionally allied to R. martinianum (subsection Selensia) but it differs in its campanulate corolla with nectar pouches, a character that excludes it from subsection Selensia. Several sheets cited in the type description are said to be referable to R. stewartianum (Cowan & Davidian, Rhododendron Yearbook 6: 177, 1952), which in some respects it resembles and of which it may be a hybrid.

Nomenclature

Type: China, SE Xizang, Tsarong, Salween/Kiu-chiang divide, NW of Si-chi-to, 13000ft, vi 1922, Forrest 21694 (holo. E)

Flags

Occurs in Countries: CN Altitude Ranges: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: cream, rose, white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):426

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Rhododendron evelyneae Danet

Erect shrub to 2m. Twigs cylindrical, 2–4mm in diameter, densely scaly and warty after the scales have fallen. Leaves erect, in pseudowhorls of 4–6 together, with some cataphylls along the internodes. Blade 20–60 x 10–30mm; apex acute to obtuse, with a hooked point that often falls early to leave a small callosity; margin entire, strongly revolute, the sides often being bent into a tube; base rounded to cordate; upper side at first densely scaly and rough, the scales quickly falling then remaining rough from the scale bases, green; lower side densely and more persistently scaly and warty. Scales orange-brown, irregularly stellate, the centres small from a stalk mounted on an acute persistent protuberance. Mid-vein slightly impressed above and prominent below. Petiole 1–3mm, grooved above, rigid and rugose. External bracts triangular to ovate, caudate to cuspidate at the apex, scaly and rough and shortly hairy outside, scaly on the margin, glabrous inside; internal bracts to 25 x 20mm, obovate-obcordate to broadly spathulate-obcordate, apiculate or mucronate at the apex, glabrous or with a few hairs outside. Bracteoles 15mm, linear, broadened to spathulate distally, sub-glabrous. Inflorescence of 3–7 hanging flowers, without scent. Pedicels 20–30 x c.1.5mm, shortly hairy and densely scaly, rough with papillae. Calyx obliquely discoid, c.4mm in diameter, sub-entire, shortly hairy and densely scaly. Corolla 30–40 x c.25mm, pink, tubular; tube 23–31 x 7 x 12mm, straight or a little curved, sometimes slightly laterally compressed, hairy and scaly outside, distinctly hairy inside; lobes 7–12mm in diameter, half-spreading to spreading, overlapping to c.½, broadly elliptic to sub-circular, rounded or a little retuse at the apex, scaly outside except near the margins. Stamens irregular, exserted to c.5mm; filaments pink, shortly hairy at the base; anthers c.3 x 1.5mm, deep purple, oblong, with rounded bases to the cells. Disc 10-lobed, glabrous except at the top where it is densely short-hairy. Ovary c.5 x 3mm, ovoid, tapering to the style, densely short-hairy and scaly, the white hairs covering the reddish-brown scales; style red or pink, slightly exserted from the mouth of the flower, shortly hairy up to halfway; stigma 5-lobed. Fruit 20 x 8mm, ellipsoid-oblong, grooved, hairy and scaly, the valves a little or not curving on dehiscence. Seeds 4–5mm including the tails.

Distribution: Indonesia, New Guinea (W), at the watershed between Mt Yonowe and Mt Jayawijaya, on the Longimik lateral moraine

Altitude: 3140-3190m

Notes

Named after the author’s mother, Evelyne Danet.

Known at present only from the type collection.

Close to R. spondylophyllum but differing chiefly in: the longer petiole, 1–3mm (1mm); the pedicels scaly and hairy (scaly only) and the style shortly hairy in the basal 1⁄3 (hairy and scaly for c.2⁄3).

Nomenclature

Type: Danet 4193, 8 Dec. 2002. Indonesia, Papua, Mt Jayawijaya east to Mt Yonowe (LYJB, BO, CANB, E, L, LAE, MAN, P).

Flags

Occurs in Countries: ID Altitude Ranges: 3,000 - 4,000m Subgenus: Vireya Habit: Non-Tree

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:106

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Rhododendron exasperatura Tagg

Shrub or small tree, 2-5m; young shoots with a dense covering of stout gland-tipped bristles. Leaves broadly obovate to elliptic, 11 — 13.5 x 6-7.5cm, 1.6—2.2 x as long as broad, apex and base rounded, upper surface glabrous, lower surface of lamina with stout gland-tipped setae that intergrade with longer gland-tipped bristles on the midrib; petioles 5- 10mm, with long bristles. Inflorescence dense, 10-15-flowered; rhachis c.5mm; pedicels c.l5mm, sparsely stipitate-glandular. Calyx 4-6mm, reddish, glabrous, lobes broad and rounded. Corolla tubular-campanulate, brick-red, with depressed nectar pouches, 35—45mm. Ovary densely stipitate-glandular; style glabrous.

Habitat: Abies forest, etc.

Distribution: NE India (Arunachal Pradesh), ne Upper Burma, China (SE Xizang)

Altitude: 3000-3700m

Notes

A distinctive species on account of its large leaves and characteristic indumentum; allied to R. erosum.

Nomenclature

Type: NE India, Arunachal Pradesh, Delei Valley, 11-12000ft, v 1928, Kingdon-Ward 8250 (nolo. E; iso. K).

Flags

Occurs in Countries: CN, IN, MM Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Hymenanthes Habit: Tree Fl. Colour: brick

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):382

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Rhododendron excellens Hemsley & Wilson

Shrub of 3 m or more. Leaves oblong-elliptic, tapered to a shortly rounded base and to the obtuse apex, 150-190 x 40-55 mm, the lower surface with slightly unequal scales about their own diameter apart. Inflorescence 3-4-flowered, pedicels c. 20 mm, densely lepidote. Calyx conspicuous, rather deeply 5-lobed, the lobes ± ovate, rounded at the apex, lepidote towards the base, glabrous. Corolla funnel-campanulate, white, c. 100 mm, the tube 75-80 mm, lepidote outside. Stamens (12-)15, much shorter than the corolla lube, filaments pubescent towards the base. Ovary densely lepidote, tapered into the style which is lepidote in the lower part. Capsule unknown.

Distribution: China (SW Yunnan)

Illustrations:

Notes

An obscure species, known only from the type collection.

Nomenclature

Type: China, Yunnan, south of the Red river from Mengtze, Henry 13666 (holo. K, photo. E)

Flags

Occurs in Countries: CN Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: white

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):36

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Rhododendron excelsum Chevalier

Small tree, c.3.5m. Leaves coriaceous, obovate to oblanceolate, 8—14 x 3-4cm, 2.5-4.5 x as long as broad, apex blunt, base cuneate, margin not undulate, entirely glabrous when mature though with red punctate hair-bases overlying the veins beneath; petioles 2-3cm, glabrous. Inflorescence 6-12-flowered; rhachis 5—15mm; pedicels 20—30mm, stipitate-glandular. Calyx c. 1.5mm, stipitate-glandular, lobes minute. Corolla apparently white, up to c.50mm. Ovary stipitate-glandular; style glandular at base, otherwise glabrous. Capsule c.20 x 8mm.

Habitat: Open forests

Distribution: Vietnam

Altitude: Around 1500m

Notes

I have not seen the single reported flowering specimen and therfore hesitate to suggest an affinity for this species. If differs from R. irroratum subsp. kontumense (also from Vietnam), however, in its white flowers and styles glandular only at base.

Nomenclature

Type: Vietnam, prov. Nhatrang, massif de Hon-la, 1500m, 2 viii 1918, Chevalier 38707-fr. (holo. P).

Flags

Altitude Ranges: 1,000 - 2,000m Subgenus: Hymenanthes Habit: Tree Fl. Colour: white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):300

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Rhododendron extrorsum J.J.Sm.

Shrub to 1.2m, with long tortuous branches and leaves only at the extreme ends. Twigs rounded, densely brown scurfy-scaly at the tips, glabrescent and rough below, blackish when dry; internodes 0.8–4cm. Leaves 4–5 together in pseudowhorls, with some much reduced ones scattered along the internodes, stiff, dull light green above, light greenish yellow beneath. Blade 10–16 x 3–7mm, ovate; apex shortly acuminate, sub-acute; margin strongly revolute, often to the mid-vein; base rounded-obtuse; very densely scaly with stellate scales on both sides initially, early glabrescent above, more slowly so beneath, leaving the surface rough. Scales deeply and irregularly narrowly divided, commonly to the minute centre; each scale shortly dendroid and mounted on top of a distinct epidermal tubercle. Mid-vein slightly grooved above, somewhat prominent beneath; lateral veins obscure. Petiole 2–3mm, thick, scaly. Bracts to 15 x 5mm, ovate, acuminate, ciliate and scaly along the outside middle line, otherwise glabrous. Bracteoles to 10mm, linear to linear-sub-spathulate, glabrous. Pedicels c.5 x 1mm, densely reddish-brown scaly. Calyx c.2.5mm in diameter, oblique, disc-shaped, very shortly obtusely 5-lobed, densely scaly. Corolla c.19mm, very pale-yellow, nearly white, broadly funnel-shaped, 5-lobed halfway or slightly more; tube 8–9 x 3–4 x 8–9mm, sub-densely covered with brown scales outside, glabrous inside; lobes c.12 x 12mm, half-spreading, wavy, sub-­circular, glabrous except for some scales at the very base outside. Stamens 7–8mm, slightly unequal; filaments linear, slightly dilated above the base, pale green, glabrous; anthers c.1.5mm, red-brown, oblong, dehiscing by distinctly outwardly facing pores. Disc very small. Ovary c.4 x 3mm, ovoid-conical, obtuse, densely stellately scaly, abruptly contracted distally; style to 1mm, very shortly obconical, glabrous; stigma convex, slightly lobed. Fruit c.12 x 6mm, ovoid, densely brown-stellate-scaly.

Habitat: Open slope, also in the saddle between the summits, scattered though common

Distribution: Indonesia, New Guinea (W), Mt Doorman.

Altitude: Around 3500m

Notes

Latin – extrorsus – towards the outside, alluding to the distinctive anther dehiscence.

Not recently recollected and never cultivated.

Nomenclature

Type: Lam 1668, 18 Oct. 1920. New Guinea (W), Northern part, Doormantop (BO, L, P).

Flags

Occurs in Countries: ID Altitude Ranges: 3,000 - 4,000m Subgenus: Vireya Habit: Non-Tree

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:81

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Rhododendron exuberans (Sleumer) Argent

Shrub to 4m. Twigs smooth, green, finely and sparsely scaly only; internodes 2–12cm. Leaves arranged in tight to loose pseudowhorls of 5–8 large and a few smaller. Blade 70–100 x 20–35mm, elliptic to broadly elliptic rarely somewhat obovate; apex acute, sometimes shortly acuminate; margin entire, flat but somewhat irregular; base tapering; obscurely scaly, the scales being very small and quickly disappearing from the upper side of the leaf. Scales sub-stellately lobed with small centres. Mid-vein distinct but smooth, hardly raised above or below; lateral veins 8–10 per side, issuing at an acute angle, very slightly impressed above. Petiole 3–5 x 2–3mm, very weakly grooved above, finely covered in scales. Flower buds (see p.327) to 35 x 15mm, narrowly ovoid, tapering to a very acute point; tips of the bracts only slightly spreading, glabrous, red. Inflorescence 1–3-flowered, an open umbel, the flowers half-hanging, orange becoming red with age, without scent. Pedicels 9 x 2mm, sparsely scaly and occasionally with a few simple hairs. Calyx a low ring, sparsely scaly. Corolla 25–38 x 25–35mm; tube c.20 x 11 x 19mm, straight, very sparsely and inconspicuously scaly outside, glabrous inside; lobes c.19 x 15mm, overlapping for c.½ their length. Stamens arranged all round the mouth of the flower, not exserted, slightly dimorphic; filaments c.15mm, glabrous or with scattered hairs at the base; anthers 5 x 2mm. Ovary 6 x 3mm, densely white-hairy and with a few scales; style c.12mm, glabrous; stigma c.2mm in diameter. Fruit 21 x 6mm, narrowly ellipsoidal. Seeds 5.2mm, without tails 0.8mm, the longest tail 2.6mm.

Habitat: Epiphytic in mossy forest

Distribution: Malaysia (Borneo), Sarawak, Mt Mulu, Mt Murud. Sabah, Mt Kinabalu (Marai-Parai), Mt Trus Madi, Mt Lumarku. Indonesia, W Kalimantan (Borneo), Mt Rajah.

Altitude: 1300-2000m

Notes

Latin – exubero – to grow luxuriantly, referring to the wider leaves than those of the related R. nervulosum.

An unusual species confined to very wet mossy forest in the wild. It was introduced into cultivation to the Royal Botanic Garden Edinburgh in 1967 but later lost and reintroduced in 1984. It grows easily and flowers well, usually in March or April in Edinburgh, but often suffers from disfigured contorted leaves and flowers if the humidity drops too low. When grown in poor light the flowers can be yellow.

Nomenclature

Type: Anderson 4596, 30 June 1961. Borneo, Sarawak, 4th Div., G. Mulu, path from Sg. Melinau Paku up W ridge, 1430m (L).

Synonymy: R. nervulosum Sleumer var. exuberans Sleumer, Blumea 1963. 12: 113.

Flags

Occurs in Countries: ID, MY Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Vireya Habit: Epiphyte, Non-Tree

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:271

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Rhododendron eymae Sleumer

Dwarf shrub to 25cm. Twigs stiffly erect, rounded, c.2mm in diameter, the tips densely covered with pale brown scurfy scales, otherwise rough and dark coloured. Leaves spirally arranged, not in proper pseudowhorls, although some areas of stem are almost bare of normal-sized leaves. Blade 8–13 x 4–7mm, ovate, elliptic or broadly elliptic; apex shortly acuminate, with acute, often mucronate points; margin entire, strongly revolute; base sub-truncate, rounded; young leaves stellate scaly on both sides, mature ones glabrescent above, persistently scaly beneath. Scales scurfy, the margin deeply stellately divided, sub-sessile, the minute centre deepened, each scale on top of a persistent epidermal tubercle. Mid-vein obscure or faintly impressed above, slightly prominent beneath, lateral veins not visible, rigid and very thick and leathery, silvery grey above, brown beneath. Petiole 1–2 x 1–2mm, very shallowly grooved, often broader than long, densely scaly. Flower buds broadly ovoid, 8–10 x c.7mm, the points appressed or slightly spreading. Bracts ovate-acuminate, densely scaly outside and on the margins, glabrous inside, to 10 x 6mm. Bracteoles filiform, glabrous, to 8mm. Inflorescence of paired or solitary flowers, rarely up to 4 together, horizontal to hanging. Pedicels 7–12mm x c.1mm, densely brown scurfy-scaly. Calyx small, densely scaly, irregularly 5-toothed, the teeth broadly triangular, sub-acute, 1mm or one or the other of them elongate to 3mm. Corolla 12–16 x 12–15mm, pale yellow, sometimes with a violet flush and with conspicuous brown scales outside; tube 8–10 x 4–5 x 7–8mm, sub-cylindrical or slightly expanded upwards, very densely brown stellate-scaly outside, glabrous inside; lobes 4–5mm in diameter, sub-erect or a little spreading, sub-spathulate to circular, densely scaly outside except for the margin, glabrous inside. Stamens slightly unequal, clustered round the mouth of the flower; filaments filiform, slightly dilated above the base, glabrous; anthers c.1.5 x 1mm, broadly oblong. Disc low, glabrous. Ovary 3–4 x c.2.5mm, ovoid-conical, very densely stellate-scaly, abruptly contracted distally; style 1.6–2mm, thick-columnar, densely scaly at the base but abruptly becoming completely glabrous; stigma shortly 5-lobed. Fruit 8–10 x 5–6mm, ovoid, shortly contracted distally, densely brown or greyish-brown scaly, with a persistent style; valves not twisted, placentae remaining coherent with the central column. Seeds 1–1.3mm, without tails c.1mm, the longest tail c.0.2mm.

Habitat: Common in the open summit areas.

Distribution: Indonesia, SW Central Sulawesi, Latimodjong Range, Mt Rantemario

Altitude: 3100-3300m

Notes

Named after Pierre Joseph Eyma, 1903–1945, who first collected this species. Eyma was a Dutch botanist who made considerable collections in Indonesia, some of which were lost due to the unrest as a result of war.

Nomenclature

Type: Eyma 684, 17 June 1937. Indonesia, Celebes, Central, Enrekang, Rante Mario (L, A, BO, K, PNH, SING, U).

Flags

Occurs in Countries: ID Altitude Ranges: 3,000 - 4,000m Subgenus: Vireya Habit: Non-Tree Fl. Colour: brown, yellow

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:73

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Rhododendron faberi Hemsley

Shrub, c.2m. Leaves elliptic to ovate-lanceolate, 6-17 x 2.8-8cm, 2-2.5 x as long as broad, apex acuminate to apiculate, base rounded, lower surface with a bistrate indumentum, the upper layer loose, composed of rust-red detersile ramiform hairs that usually do not persist, the lower compacted, whitish, persistent; petioles 0.5-2cm, densely tomentose. Inflorescence 7—20-flowered; rhachis up to 10mm; pedicels (15—)25—30mm, densely glandular. Calyx 7-10mm, sparsely glandular, lobes broad, divided almost to base. Corolla campanulate to funnel-campanulate, white or cream to pink, sometimes with crimson flecks and/or a basal blotch, 30-40mm. Ovary densely stipitate-glandular, sometimes also hairy; style glabrous or glandular at base. Capsule 15-20 x c.5mm.

Distribution: China (C Sichuan)

Altitude: 3050-4400m

Notes

At their extremes the two subspecies are very distinct. However there are intermediates, especially from around Tatsien-lu (Kang-ting Xian). These intermediates include the type of R. bureavioides Balfour f. (Notes R.B.G. Edinb. 13:35,1920) from W China, 1904, Wilson 3954 (holo. K; iso. A), with the large leaves of subsp. prattii but a thicker, more persistent upper layer of leaf indumentum than is usual in subsp. prattii. R. faberi resembles R. bureavii and R. nigroglandulosum in its well-developed calyx and glandular ovary but differs from both in its clearly bistrate leaf indumentum which suggests an affinity with R. rufum.

Flags

Occurs in Countries: CN Altitude Ranges: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: cream, crimson, pink, white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):359

Rhododendron faberi subsp. faberi

Leaves 6-11 x 2.8—4.5cm, when juvenile with upper layer of indumentum dense

Illustrations:

  • Fang, PL Omeiens. t.24 (1942)
Nomenclature

Type: China, Sichuan, summit of Mt Omei, Faber (holo. K)

Synonymy: R. faberioides Balfour f., Notes R.B.G. Edinb. 13: 44 (1920). Type: China, W Sichuan, vi 1908, Wilson 3436 (holo. K). R. wuense Balfour f., ibid. 13: 64 (1920). Type: China, SW Sichuan, Mt Wu, Wilson 3960 (A,K)

Rhododendron faberi subsp. prattii (Franchet) Chamberlain

Leaves 10-17 x 5-8cm, when juvenile with upper layer of indumentum sparse

Illustrations:

  • Bot. Mag. 158: t.9414 (1935)
Nomenclature

Synonymy: R, prattii Franchet, J. Bot. (Morot) 9: 389 (1895). Syntypes: China, Sichuan, aux environs de Ta-tsien-lou, Pratt 58 (A, E, K); Soulie 8 bis, n.v. R. leei Fang, Acta Phytotax. Sin. 2: 82 (1952). Type: China, Sichuan, Hsi-shui-lo, Mow Hsien, 2850-3000m, 21 vi 1951, Lee, T. C. 2210 (holo. SZ)

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Rhododendron facetum Balfour f. & Kingdon-Ward

Shrub or tree, 2-10m; young shoots rufous stellate-tomentose. Leaves oblanceolate to elliptic, 10-18.5 x 3-7.2cm, 2.3-3.2 x as long as broad, apex rounded, apiculate, base cuneate, both surfaces glabrous when mature or with vestiges of indumentum, especially on the midrib towards the base; petioles slender to stout, 2—3cm, stellate-tomentose at first, soon glabrescent. Inflorescence c.lO-flowered; rhachis 10-15mm; pedicels 10-15mm, stellate-tomentose, sometimes also stipitate-glandular. Calyx 3-5mm, stellate-tomentose, lobes broad, rounded. Corolla tubular-campanulate, sparingly floccose-tomentose or glabrous on outer surface, deep rose to scarlet, 0-50mm. Ovary densely rufous stellate-tomentose; style with floccose stellate hairs and glands. Capsule 15-20 x 8 mm, slightly curved.

Habitat: Forests

Distribution: NE Upper Burma, China (W Yunnan)

Altitude: 2700-3350m

Illustrations:

Notes

Allied to R. kyawi but lacking the setose glands on the young shoots, also closely allied to R. huidongense (q.v.).

The correlation between stout petioles and glandular pedicels, proposed by Tagg to distinguish between R. eriogynum and R. facetum does not hold for specimens now available. The latter name was chosen rather than the former as it already had a wider acceptance.

Nomenclature

Type: E Burma, Fengshui-ling camp, 8-9000ft, 9 vi 1914, Kingdon-Ward 1659 (holo. E)

Synonymy: R. eriogynum Balfour f. & W. W. Smith, Notes R.B.G. Edinb. 10: 101 (1917). Type: China, Mid W Yunnan, Ghi-shan, E of Tali Lake, 9000ft, viii 1914, Forrest 13508 (holo. E).

Flags

Occurs in Countries: CN, MM Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Hymenanthes Habit: Tree Fl. Colour: rose, scarlet

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):377

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Rhododendron faithae Chun

Shrub, c. 4 m. Leaves elliptic, 16-22.5 x 6-8.5 cm, 2.5-3.2 x as long as broad, apex rounded, mucronate, base rounded, lower surface glabrous; petioles 3-4 cm, glabrous. Inflorescence c. 10-flowered; rhachis c. 50 mm; pedicels 25-35 mm, stipitate-glandular. Calyx c. 2 mm, with shallow, stipitate-glandular lobes. Corolla c. 7-lobed, open-campanulate, sparsely stipitate-glandular outside, glabrous within, probably white and lacking flecks, 75-90 mm. Stamens c. 14, filaments glabrous. Ovary and entire style glandular. Capsule not known

Distribution: China (Guangdong, Guangxi)

Notes

Closely resembling R. diaprepes but differing in the glabrous filaments, etc. A large-leaved fruiting specimen from Jiangxi, Wilson 'A'1686, may belong to this species.

Nomenclature

Type: China, Guangdong, Sunji, Shektung, 21 vii 1931, Koy S. P. 51693 (holo. Herb. Inst. Bot. Guangzhou; iso. E)

Flags

Occurs in Countries: CN Subgenus: Hymenanthes Habit: Non-Tree

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):233

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Rhododendron falconeri Hooker f.

Tree, 6-12m. Leaves broadly elliptic to obovate, 18-35 x 8-17cm, 1.4-2.3 x as long as broad, apex rounded, base rounded to cordate, upper surface glabrous or scurfy, rugulose, lower surface with a bistrate indumentum, the lower layer white and compacted, the upper a dense rufous tomentum composed of strongly fimbriate, narrowly cup-shaped hairs; petioles terete, 2.5-5cm, sparsely floccose and stipitate-glandular. Inflorescence 15-20-flowered; rhachis stout; 30-60mm; pedicels 40-55mm, densely stipitate-glandular, viscid. Calyx c.2mm, viscid-glandular. Corolla fleshy, 8(-10)-lobed, obliquely campanulate, whitish to cream, or pale pink with darker tips, purple basal blotch present, 40-50mm. Stamens 12-16. Ovary densely viscid-glandular. Capsule c.40 x 10mm, straight.

Habitat: Deciduous and mixed forests

Altitude: 2700-3750m

Flags

Occurs in Countries: BT, IN, NP Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Hymenanthes Habit: Tree Fl. Colour: cream, pink, purple

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):259

Rhododendron falconeri subsp. exinuum (Nuttall) Chamberlain

Corolla pale pink with darker tips; leaves scurfy above, even at maturity

Distribution: NE India (Arunachal Pradesh)

Illustrations:

  • Bot. Mag. 119: t. 7317 (1893)
Notes

Closely allied to subsp. falconeri and apparently replacing it in the east. A fruiting specimen (Ludlow &. Sherriff29S9) from S Bhutan could belong to either subspecies. A specimen from the Subansiri district of Arunachal Pradesh, with relatively narrow leaves, c.2.5 x as long as broad, that are glabrous above and only slightly rugose, but with deep rose-pink flowers (Cox & Hutchison 421), may be a hybrid of subsp. eximium.

Nomenclature

Synonymy: R. eximium Nuttall, Hooker's J. Bot. Kew Gard. Misc. 5: 364 (1853). Type: NE India, Arunachal Pradesh, Oola Mountain, 10-11000ft, Booth (holo. K).

Rhododendron falconeri subsp. falconeri

Corolla white to cream; leaves glabrous above at maturity

Distribution: E Nepal, N India (Bengal, Sikkim, Arunachal Pradesh), Bhutan

Illustrations:

  • Bot. Mag. 82: t. 4924 (1856)
Notes

Three specimens from Duke La & Pele La in C Bhutan (Cooper 3911, 3968; Grierson & Long 1085) with pink to lilac flowers, broad, non-rugulose leaves and a fawn lanate sub-cupular indumentum have almost certainly been derived by hybrisation from R. falconeri. To what extent they are part of a stabilised hybrid population is not certain. Their status therefore remains doubtful. It is however noted that a plant assigned to R. falconeri, with yellow flowers and rugose leaves, but with the same sub-cupular indumentum (Ludlow & Sherriff 3041) originated from Chendebi, not far from Pele La.

Nomenclature

Type: N India, Bengal, Tonglu, 10000ft, Hooker(holo. K)

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Rhododendron fallacinum Sleumer

Shrub or small tree to 6m. Twigs rounded, rough with a dense covering of dark brown scales; internodes 2–10cm. Leaves 3–6 in tight pseudowhorls and with small, slender scale leaves arranged along the stems but these soon falling off. Blade 80–160 x 30–55mm, sub-sessile, ovate, or ovate-elliptic; apex shortly to long acuminate or sub-­caudate, acute; margin irregularly wavy, flat; base rounded to auriculate; densely silvery scaly above, only disappearing gradually; beneath densely overlapping coppery-brown-scaly. Scales variable in size, strongly lobed, the broad margins striate; the centres large and darker especially those of the largest scales. Mid-vein slightly impressed in the proximal ½ above, strongly raised below for most of its length and especially at the base; lateral veins 8–12 per side, wide-spreading, distinctly indicated but not raised or impressed on the upper surface, slightly raised or very obscure on the lower side. Petiole to 4 x 4mm, very short, rarely longer than broad, densely brown-scaly, not or only weakly grooved above in the fresh state. Flower buds broadly ovoid with the bud scales appressed. Bracts densely scaly in a broad central band on the outer side of each bud scale and conspicuously fringed with white hairs on the margins. Bracteoles to 15mm, filiform and papillose below, spathulate and long hairy above. Inflorescence of 15–35 flowers in a complete or sometimes open umbel. Flowers standing erect to horizontal. Pedicels 15–35 x c.1mm, densely brown-scaly. Calyx a low, scaly ring. Corolla 18–25 x 30–37mm, bright orange, without scent; tube 7–12 x 5 x 5mm, densely scaly outside; lobes 16 x 16mm, widely spreading, overlapping to c.halfway and with a triangular area of scales on the outside. Stamens at first standing erect centrally in the mouth of the flower, later reflexing back away from the stigma against the corolla lobes; filaments 12–16mm, slightly broader proximally and hairy in the basal ½; anthers 3–4mm, brown. Ovary 5.5–7 x 1.5–2mm, densely scaly; style 8–12mm, scaly at the base otherwise glabrous; stigma 5-lobed, to 3mm in diameter. Fruit to 35 x 4mm. Seeds 6mm, without tails 0.9mm, the longest tail 3.5mm.

Habitat: Mostly terrestrial, less commonly epiphytic in mossy forest in damp shady places, but also on open exposed ridges, often common.

Distribution: Malaysia (Borneo), Sabah, Mt Kinabalu, Mt Trus Madi and the Crocker Range. Sarawak, Mt Mulu.

Altitude: 1220-2600m

Notes

Latin – fallax – deceptive or fallacious, because of a deceptive resemblance to R. durionifolium which allowed it to go unrecognised for many years.

It was noted by Sleumer (1966) that ‘sterile specimens [were] hardly distinguishable from those of R. durionifol­ium’. In fact this species is not clearly distinguished from R. durionifolium but is retained here at present. Flower size is extremely variable (see under R. durionifolium) and pedicel length varies enormously as it elongates after the flowers open, even before the corolla has fallen. This leaves only relative scalyness of the corollas and corolla tube length to distinguish between these two species. As conceived here R. fallacinum has flowers with a relatively short and extremely scaly tube, with the scales extending up onto the backs of the lobes, while R. durionifolium

Rhododendron fallacinum has been collected in flower in most months of the year but probably flowers best in the wild from February to April. Pollinators might be expected to be butterflies with the bright display of orange-red flowers with short floral tube and prominently displayed anthers, but Scarlet Sunbirds (Aethopyga mystacalis Temminck) have been seen visiting the flowers. Several hybrids have been recorded with this species in Sabah: x stenophyllum occurs on Mt Alab – it has narrow linear leaves and broad dark scales but has not been seen with flowers; x rugosum occurred on the Mesilau Spur, Kinabalu – it has a mixture of scale types and handsome red flowers; x lamrialianum occurs commonly on Mt Trus Madi and has been seen above the Mesilau Cave – it has intermediate-sized leaves but has not been seen in flower; and x acuminatum, also from the Mesilau Spur, is known only in vegetative form from its intermediate leaves.

Nomenclature

Type: Clemens 32714. East Malaysia, Sabah (Borneo), Mt Kinabalu (L, A, BM, BO, E, NY).

Flags

Occurs in Countries: MY Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Vireya Habit: Epiphyte, Tree Fl. Colour: brown, orange

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:114

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Rhododendron farinosum Leveille

Shrub, 1—5m. Leaves coriaceous, obovate-lanceolate, c.7 x 3cm, 2.3 x as long as broad, apex blunt, ± cucullate, upper surface glabrous, bullate with deeply impressed veins, lower surface with a bistrate indumentum, the lower layer white and compacted, the upper yellowish at first, becoming silvery, lanate-tomentose, hairs ramiform, persistent but with veins exposed; petioles c.lcm, densely tomentose. Inflorescence c.lO-flowered; rhachis c.5mm; pedicels c.lOmm, densely tomentose. Calyx c. 1.5mm, tomentose, lobes minute. Corolla campanulate, white, 30-35mm. Ovary densely tomentose; style glabrous. Capsule not known.

Notes

Closely allied to both R. floribundum and R. denudatum but differing from both in its smaller, cucullate-tipped leaves and white flowers, and from R. denudatum (also recorded from lo-chan) in its dense, more persistent leaf indumentum.

Nomenclature

Type: China, Yunnan, Flanc de lo-chan, 3200m, v 1913, Maire (holo. E).

Flags

Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):321

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Rhododendron farrerae Tate apud Sweet

Dwarf shrub; young shoots becoming glabrous. Leaves ovate, 1.5-3 x l-2cm, apex acute, upper and lower surface with long brown hairs, becoming glabrous; petioles l-3mm, densely villose. Inflorescence 1-2-flowered; pedicels short, hidden by bracts, densely villose. Calyx minute, densely villose. Corolla open-campanulate, pale purple or lilac, upper lobe spotted, 20-30mm, lobes 15mm, broadly oblong. Stamens 10, unequal, glabrous. Ovary densely hairy; style glabrous. Fruit not known.

Habitat: Mixed woodland

Distribution: China (E Guangxi, Guangdong, Fujian, Jangxi, Hunan)

Altitude: Around 600m

Illustrations:

Notes

Forms with more or less crenate leaves have been referred to R. cinereoserratum Tan, the type of which has unusually narrow leaves. However, there are specimens with broader but toothed leaves and there are also analagous forms of R. mariesii. We do not therefore consider that there is any justification in maintaining R. cinereoserratum as a distinct taxon.

Nomenclature

Type: a plant introduced by Capt. Farrer from China in 1829 (n.v.)

Synonymy: Azalea farrerae (Tate) Koch, Dendr. 2(1): 178 (1872). Rhododendron farrerae Tate var. leucotrichum Franchet, J. Bot. (Morot) 394 (1895). Syntype: China, E Sichuan, aux environs de Tchen-keou-tin. Farges 50, 846, n.v. Azalea squamata Lindley, J. Hort. Soc. Lond. 1:152 & Bot. Reg. t.3 (1847). Type: China, Hongkong, Mt Victoria, 550m, Tate (holo. BM), Rhododendron cinereoserratum P.X.Tan, Bull. Bot. Res. N.E. Forest. Inst. 2(4): 77 (1982). Type: China Fujian, Nanjing Xian, Hexi, Ling hai, Univ. Amoy 20 (holo. Amoy Univ.)

Flags

Occurs in Countries: CN Altitude Ranges: 0 - 1,000m Subgenus: Tsutsusi Habit: Non-Tree Fl. Colour: lilac, purple

Chamberlain, D.F. & Rae, S.J. (1990) A Revision of Rhododendron IV Subgenus Tsutsusi. Edinburgh Journal of Botany 47(2):144

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Rhododendron fastigiatum Franchet

Prostrate, tufted shrub, or forming a compact cushion, to 1 -5 m. Leaves (4-5-)7-14(-16) x (2-8-)3-6(-9) mm, oblong, broadly elliptic or ovate, apex rounded to subacute, mucronate, base cuneate or subtruncate, undersurface fawn to greyish with the scales contiguous in groups or more scattered. Inflorescence l-3(-4)-flowered, pedicels lepidote, 0.5-3 mm. Calyx 2.5-5-5 mm, lobes oblong or bluntly triangular, apex rounded or acute, scaling variable, margin usually ciliate. Corolla bright lavender-blue to pinkish or rich purple, funnel-shaped (9-5-) 10-15.5(-18) mm, tube 3-6-5(-8) mm, pubescent inside and rarely also outside, usually elepidote outside. Stamens (6-)10, filaments pubescent towards the base. Ovary lepidote, occasionally with an apical tuft of hairs, style exceeding the stamens, glabrous or rarely pubescent and/or lepidote at the base. Capsule ovoid, 5-6 mm, lepidote.

Habitat: Open stony pastures, screes, cliffs and in forest

Distribution: China (N & C Yunnan)

Altitude: 3400-4400m

Notes

The Philipsons (1975, p. 38) record a natural hybrid with R. rupicola var. rupicola.

Nomenclature

Type: China, Yunnan, in monte Tsang-chan supra Tali, vi 1883, Delavay 360 (holo. P; iso. A, E p.p., K)

Synonymy: R. nanum Leveille, Feddes Rep. 12:285 (1913). Type: China, Yunnan, 1911, Maire (holo. E). R. capitatum sensu Franchet, Bull. Soc. Bot. Fr. 32:7 (1885) non Maximowicz (see p. 107)

Flags

Occurs in Countries: CN Altitude Ranges: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: lavender, pink, purple

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):100

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Rhododendron faucium Chamberlain

Shrub or small tree, 1.5-5(-6.5)m; bark smooth; young shoots ± glabrous. Leaves oblanceolate, 7—12 x 2.5-3.5cm, usually widest in the upper third, 2.8-3.5 x as long as broad, apex rounded, base cuneate, upper surfaceglabrous, lower surface greenish, epidermis epapillate, with a few scattered hairs near the midrib towards the base, also with persistent red punctate hair-bases overlying the veins; petioles 0.7-1.5cm, stipitate-glandular, often winged for part of their length. Inflorescence compact, 5-10-flowered; rhachis (8-)10-20mm; pedicels 5-10mm, glabrous or stipitate-glandular, sometimes also with dendroid or crisped hairs. Calyx 3-5mm, chartaceous, glandular-ciliate, otherwise glabrous. Corolla campanulate, pink to white tinged pink or rarely sulphur yellow, with purple flecks, 37-40mm. Ovary densely stipitate-glandular, style glabrous. Capsule not known.

Habitat: Forest margins, rock faces

Distribution: China (SE Xizang)

Altitude: 2600-3350m

Notes

R. faucium is closely allied to R. hylaeum but differs in the smaller leaves that taper below, the shorter petioles, and the glandular ovary. The punctate hair-bases on the lower surface of the leaves confirm the affinity with R. hylaeum.

Ludlow, Sherriff & Elliot 13594 & 13620, which differ in their darker pink flowers and more acute leaves, show some of the characters of R. ramsdenianum (subsection Irrorata) but are otherwise closer to the present species.

Nomenclature

Type: China, SE Xizang, Pome Province, Layoting, Tongyuk Chu, 9000ft, 12 iii 1947, Ludlow, Sherriff & Elliot 12289 (holo. E; iso. BM)

Flags

Occurs in Countries: CN Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Hymenanthes Habit: Tree Fl. Colour: pink, purple, white, yellow

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):421

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Rhododendron feddei Leveille

Shrub 4 m high, young branches glabrous. Leaves glabrous except for scattered stiff bristles on the mid-rib below and on the petiole; blade oblanceolate, c.130 x 32 mm, tapered to the base, apex slightly acuminate, coriaceous, veins forming a close network; petiole c. 10-12 mm long. Inflorescence buds lateral, at the ends of leafy shoots, c.5-flowered; bud scales not seen; pedicel glabrous, 25-30 mm long. Calyx an undulate rim, glabrous. Corolla not seen, Stamens not seen. Ovary glabrous. Capsule narrowly cylindric, c.25 x 3 mm, glabrous.

Distribution: China (Guizhou)

Notes

The stiff bristles on the underside of the mid-rib and the close network of veins make the leaves of this species readily recognizable. The species is evidently rare. Besides three collections by Cavalerie we have seen only one other (Tsiang 8456).

Nomenclature

Type: China, Guizhou, Pin Fa, 18 vi 1903, Cavalerie 1074 (holo. E).

Flags

Occurs in Countries: CN Subgenus: Azaleastrum Habit: Non-Tree

Philipson, W.R. & Philipson, M.N. (1986) A Revision of Rhododendron III. Subgenera Azaleastrum, Mumeazalea, Candidastrum and Therorhodion. Notes from the Royal Botanic Garden Edinburgh 44(1):9

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Rhododendron ferrugineum Linnaeus

Small shrub with erect or ascending branches, to 1.5 m. Young growth densely lepidote, sometimes with a few loriform hairs. Leaves narrowly elliptic to elliptic, acute or mucronate at the apex, 28-40 x 8—16 mm, slightly revolute, dark shining green above, ferrugineous beneath with dense overlapping scales. Inflorescence many-flowered, the rachis 10-20 mm, filiform-acicular pubescent, pedicels rather strict, densely lepidote. Calyx small, 5-lobed, lobes up to 1-5 mm, lepidote and loriform-ciliate. Corolla 12-15(-17) mm, tube 6-9(-10) mm, deep pink, rarely pale pink or white, lepidote and usually filiform-acicular pubescent outside. Stamens 10, filaments pubescent towards the base. Ovary 5-locular, lepidote, style glabrous, up to 2 x longer than the ovary. Capsule sparsely lepidote, ± oblong, 5-7 mm.

Habitat: Mountain slopes, open woodland and scrub.

Distribution: Austria, France, Germany, Italy, Spain, Switzerland (Alps and Pyrenees)

Illustrations:

Notes

The type species of the genus

Nomenclature

Type: Habitat in Alpibus Helveticis, Allobrogicis, Pyrenaeis'

Flags

Occurs in Countries: AT, CH, DE, ES, FR, IT Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: pink, white

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):110

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Rhododendron flammeum (Michx.) Sargent

Shrub or small tree to 2.5m tall, usually non-rhizomatous; young twigs red-brown, densely covered with unicellular and multicellular eglandular hairs. Vegetative bud scales glabrous, to densely covered with unicellular hairs abaxially; margin unicellular-ciliate. Leaf blade membranaceous, ovate or obovate to elliptic, (2.9-)3.9-6.3(-8.2) x (1.3-)1.5-2.4(-2.7)cm; base acute to oblique; apex acute to obtuse, often mucronate; adaxial surface glabrous or sparsely covered with multicellular eglandular hairs or with unicellular hairs, the midvein densely covered with unicellular hairs; abaxial surface densely covered with unicellular or multicellular eglandular hairs, or with both, or glabrous, the midveie sparsely to densely covered with unicellular hairs and multicellular eglandular hairs; margin entire, ciliate with multicellular eglandular hairs; petiole Q.2-0.6cm long, sparsely to densely covered with unicellular and multicellular eglandular hairs. Flower bud scales chestnut brown; abaxial surface sparsely to densely covered with unicellular hairs, rarely completely glabrous; margin unicellular-ciliate. Flowers appearing before or with the leaves', inflorescence a shortened raceme of 6 to 11 flowers. Pedicels (0.3-)0.5-0.9(-1.0)cm long, sparsely to densely covered with unicellular and multicellular eglandular hairs. Sepals less than 0.1-0.3(-0.5)cm long, often varying in length on the same flower; margins setose with multicellular eglandular hairs; abaxial surface sparsely covered with unicellular and multicellular eglandular hairs. Corolla scarlet, reddish orange to orange, fragrance acrid, the tube longer than the limb and abruptly expanding into it; upper corolla lobe 0.8-1.7(-2.2) x(0.7-)0.8-1.6(-1.9)cm wide; lateral lobes (1.0-)1.1-1.8(-2.1) x (0.5-)0.6-1.0(-U)cm; corolla tube (1.7-)1.8-2.3 (-2.5)cm long, 0.2-0.3(-0.4)cm wide at base; outer surface of corolla sparsely covered with unicellular and multicellular eglandular hairs, the multicellular hairs continuing up the corolla lobes, rarely with unicellular and multicellular gland-tipped hairs (glands of hairs minute, poorly developed); inner surface of corolla densely covered with unicellular hairs. Stamens (4.0-)4.3-6.3(-7.3)cm long, with dense terete or flattened unicellular hairs on proximal (2.0-)2.1-2.8 (-3.3)cm of filament, exserted (2.4-)2.5-3.9(-5.0)cm beyond throat of corolla. Style (4.5-)4.9-6.8(-7.4)cm long, exserted (3. l-)3.3-5.0(-5.4)cm beyond throat of corolla, with dense unicellular hairs on proximal (0.0-)0.1-1.4(-2.2)cm; stigma 0.1-0.2(-0.4)cm wide. Ovary 0.3-0.4(-0.5)cm long, 0.1-0.2(-0.3)cm wide at the base, densely covered with multicellular eglandular hairs over unicellular hairs. Capsules L5-2.3(-2.6) x 0.5-0.7(-0.8)cm, ovate, sparsely covered with unicellular hairs and moderately to densely covered with multicellular eglandular hairs. Seeds pale to dark chestnut brown, ovate or elliptic to fusiform, (1.8-)2.0-2.7(-2.8) x 0.7-1.l(-1.2)mm, body 0.9-1.3 x 0.4-0.7(-0.8)mm; testa expanded and dorsiventrally flattened, surrounding the body, the cells elongate over the body of the seed, short in the expanded portion of the testa, with transverse end-walls (Fig. 5). Chromosome number: In = 26 (Li, 1957). Figure 31; see additional illustrations in Prince, 1978 (photo) and Galle, 1985 (photo).

Habitat: Upland woods, dry slopes and ridges, bluffs of rivers or stream banks, sandhills

Distribution: USA: Georgia and South Carolina

Altitude: 0-500m

Notes

Hybrids between R. flammeum and R. canescens have been studied by the present author at Stone Mountain, Georgia (Kron et al., 1993). This population is most likely the same as T. G. Harbison's #900 collection noted by Rehder (1921). The hybrids at Stone Mountain are intermediate in flower colour (pink with a yellow blotch on the upper corolla lobe), in floral bud-scale pubescence (the population of the probable R. flammeum parent possesses glabrate bud scales, and those of the probable R. canescens parent possess densely unicellular pubescent bud scales), and in plant height (see Appendix under hybrids of R. canescens).

Although the name Rhododendron speciosum (Willd.) Sweet is often used for the Oconee azalea, it is not the correct one. Willdenow (1811) cites Michaux's (1803) Azalea calendulaceo in his description of Azalea speciosa. In doing this Willdenow thus included the type of a previously validly published name (Azalea calendulacea Michaux) making Azalea speciosa Willd. superfluous (International Code of Botanical Nomenclature, 1981, Art. 63.2). The correct name for the Oconee azalea is Rhododendron flammeum (Michaux) Sargent since Sargent (1917) raised Michaux's A. calendulacea vax.flammea to specific rank.

Flowering in April

Rhododendron flammeum, a species that is rather variable in corolla colour and in the pubescence of the floral bud scales, is related to R. prunifolium and R. cumberiandense (see Phylogenetic Analysis). These three red to orange-flowered species are isolated geographically. Rhododendron flammeum can be distinguished from both by its flowering before or with the expansion of the leaves. While it is marginally sympatric with R. calendulaceum, R. flammeum is reproductively isolated from it by the tetraploid condition of R. calendulaceum and the discontinuous distribution of R. flammeum. Although the flower colour is similar between R. calendulaceum and R. flammeum, they can be distinguished from one another by the eglandular corolla tube and the unicellular-ciMate floral bud-scale margins in R. flammeum vs. the densely glandular corolla tube and the glandular floral bud-scale margins in R. calendulaceum.

Nomenclature

Synonymy: Azalea calendulacea Michx. Nm.flammea Michx., Fl. Bor.-Amer. 1: 151 (1803). Type: Georgia: Savannah River, Two Sisters Ferry. 26-27 iv 1787, A Michaux s.n. (lecto. P-MICHX; photo of holo. A). Azalea nudiflora var. coccinea Aiton, Hort. Kew. 1: 202 (1787). A. periclymenoides var. coccinea (Aiton) Pursh, Fl. Am. Septentr. 1: 152 (1814). Rhododendron nudiflorum var. coccineum (Aiton) Sweet, Hort. Brit. ed. 2, 343 (1830). Type: n.v.

Flags

Occurs in Countries: US Altitude Ranges: 0 - 1,000m Subgenus: Pentanthera Habit: Tree Fl. Colour: orange, red

Kron, K.A. (1993) A Revision of Rhododendron Section Pentanthera. Edinburgh Journal of Botany 50(3):311

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Rhododendron flavantherum Hutchinson & Kingdon Ward

Very similar to R. monanthum, differing as follows: leaves less clearly papillose beneath, the scales more distant, pale; calyx 5-lobed, the lobes broadly triangular, ± obtuse, c. 2.5 mm

Habitat: North-facing cliffs

Distribution: China. (SE Xizang)

Altitude: 2450-2750m

Notes

Known only from the type collection; doubtfully distinct from R. monanthum.

Nomenclature

Type: China, Tibet, Tsangpo gorge near Churung confluence, 8-9000 ft, 25 ii 1924, Kingdon Ward 6313 (iso. E)

Flags

Occurs in Countries: CN Altitude Ranges: 2,000 - 3,000m Subgenus: Rhododendron Habit: Non-Tree

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):60

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Rhododendron flavidum Franchet

Erect shrub to 2.5 m. Leaves 7-15 x 3-7 mm, broadly elliptic to oblong, apex rounded, shortly mucronate, base broadly to narrowly cuneate, undersurface pale grey-green with well-spaced scales. Inflorescence 1-3-flowered, pedicels pubescent, sometimes with a few scales as well, 1-4 mm. Calyx 2-4(-7) mm, minutely pubescent at the base, lobes strap-shaped or deltoid, acute, sometimes unequal, sparsely lepidote or elepidote, ciliate. Corolla yellow, broadly funnel-shaped, pubescent outside and inside, 12-18 mm, tube 4-7 mm, elepidote or sparsely lepidote. Stamens (8-)9-10, ± equal to the corolla, filaments pubescent towards the base. Ovary densely lepidote, style exceeding stamens, pubescent at base. Capsule ovoicl, lepidote, c. 6 mm.

Notes

Two varieties can be distinguished

Flags

Occurs in Countries: CN Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Rhododendron Habit: Non-Tree

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):101

Rhododendron flavidum var. flavidum

Scales on leaf undersurface uniform in colour; calyx lobes 2-4(-7) mm

Habitat: Alpine regions

Distribution: China (NW Sichuan)

Altitude: 3000-4000m

Nomenclature

Type: China, 'E Tibet'(sic!), Tatsienlou, 1893, Soulie 625 (iso. E)

Synonymy: R. primulinum Hemsley, Gard. Chron. 47:4 (1910). Type: a cultivated specimen (holo. K)

Rhododendron flavidum var. psilostylum Rehder & Wilson

Scales on leaf undersurface dimorphic, some dark, the rest golden; calyx lobes c. 2 mm

Distribution: China (NW Sichuan)

Notes

Known only from one collection

Nomenclature

Type: China, Szechuan, west of Kuan hsien, summit of Niu-tou-shan, 3300 m, 20 vi 1908, Wilson 3452 (holo. A; iso. BM, E, K)

Synonymy: R. psilostylum (Rehder & Wilson) Balfour f., Notes R.B.G. Edinb. 11:104(1919)

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Rhododendron flavoviride J.J.Sm.

Erect shrub or tree to 10m. Twigs 2–4mm in diameter, rounded, green, densely pale brown or translucently scaly, becoming glabrescent; internodes 2.5–8cm. Leaves 3–6 together in tight pseudowhorls at the upper 1–3 nodes. Blade 30–70 x 20–33mm, broadly-elliptic or ovate-­elliptic sometimes obovate-elliptic; apex obtuse or rounded; margin narrowly to broadly revolute; base rounded, or broadly tapering; initially scaly on both sides, glabrescent above, the scales leaving dense, minute, black pits, more persistently and sub-densely scaly beneath. Scales flat, or concave, marginal zone wide, transparent, shortly sub-stellately-lobed; centre minute, impressed becoming dark. Mid-vein narrow and slightly impressed above, grooved proximally for a few millimetres, beneath strongly raised to within c.1cm of the apex; lateral veins 4–8 per side, spreading at a wide angle, irregular, anastomosing, slightly depressed above and raised beneath in dried leaves, reticulation dense, slightly impressed above, faintly to markedly raised beneath. Petiole 3–11 x 2–3mm, grooved above, densely scaly. Flower buds to 30 x 16mm, narrowly ovoid, acutely to broadly and bluntly pointed, smooth, green, but with just the basal bracts with the tips becoming revolute. Bracts broadly spathulate, glabrous except for a fringe of brown scales along the edges, hooded and emarginate at the apex, green along a broad median stripe, translucent towards the edges. A few of the shortest bracts with brown scales outside. Bracteoles to 20mm, linear to linear-spathulate, glabrous or with a few scales on the margins apically. Inflorescence a 3–6-flowered open umbel. Pedicels 10–30 x c.1.5mm, densely covered with pale brown appressed, sub-stellate scales, without hairs. Calyx 4–5mm in diameter, obliquely disc-shaped, shortly and obtusely 5-lobed. Corolla 45–50 x 33–42mm, on opening almost horizontal, becoming vertically hanging, pale-green, fragrant or without scent; tube 35–38 x 6–8 x 12–15mm, sub-cylindrical, distinctly curved, laxly but obscurely, sub-stellate-scaly outside, shortly hairy inside; lobes 16 x 18mm, sub-circular, spreading horizontally or sometimes a little reflexed, overlapping to about ½ their length, with a few very small scales near the base outside. Stamens exserted to 9mm, clustered around the style on the lower side of the mouth; filaments green, filiform, sub-densely to laxly patently hairy in the proximal ½; anthers 2.5–3 x 1mm, cream to pale brown, oblongoid curved, the base obtuse. Disc glabrous or hairy at the upper margin. Ovary c.5 x 2mm, sub-cylindrical-conical, base and apex tapering, yellowish or silvery, densely sub-patently hairy, the hairs covering small scales; style at first with the stigma just below the anthers in the mouth of the flower, later exserted to 15mm, hairy and scaly in the proximal ¼–1⁄3, scaly and sometimes very laxly hairy up to the middle, glabrous above; stigma globose.

Habitat: In open, swampy localities, or on the edge of sub-montane forest.

Distribution: Indonesia, New Guinea (W), Oranje Mts, Kajan Mts and near Lake Habbema.

Altitude: Around 3200m

Notes

Latin – flavus – pale yellow; viridi – green. Alluding to the flower colour.

Nomenclature

Type: Pulle (Versteeg) 2455, 9 Feb. 1913. New Guinea (W), Kajan Mts, 3200m (BO, K, L, U).

Flags

Occurs in Countries: ID Altitude Ranges: 3,000 - 4,000m Subgenus: Vireya Habit: Tree

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:216

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Rhododendron fletcheranum Davidian

Very similar to R. valentinianum, differing as follows: leaves with distant scales beneath, the surface conspicuous, green; leaf margin distinctly crenate in the upper half; midrib usually not setose above; ovary conspicuously setose towards the apex, the setae persisting on the capsule.

Habitat: Forests at 4000-4300 m

Distribution: China (SE Xizang)

Illustrations:

Notes

Known only from two collections; vicariating with the very similar R. valentinianum

Nomenclature

Type: SE Tibet, province of Tsarung, forests and alpine regions of the Solo-la, 14000 ft, vi-vii 1922, Rock 22302 (holo. E)

Flags

Occurs in Countries: CN Subgenus: Rhododendron Habit: Non-Tree

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):42

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Rhododendron fleuryi Dop

Shrub, 3-5 m. Leaves oblong-lanceolate, tapering to base and apex, 50-80 x 20-40 mm, margins somewhat loriform-ciliate, dark green above, brownish beneath with dense almost contiguous scales; petioles loriform-ciliate. Inflorescence 5-6-flowered, pedicels sparingly lepidote, markedly recurved in fruit. Calyx disc-like, glabrous. Corolla white with 5 yellow lines on the tube, c. 40 mm, glabrous. Stamens 10, filaments pubescent towards the base. Ovary lepidote, tapering into the style which is sparsely lepidote.near the base.

Habitat: Hillsides

Distribution: Laos

Altitude: 2000-2500m

Illustrations:

Nomenclature

Type: Laos, prov. Darlac, massif du Langbian, au sommet du piton du Langbian, 2000-2500 m, Chevalier 30896 (holo. P)

Flags

Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: yellow

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):54

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Rhododendron floccigerum Franchet

Shrub, 0.6-3m; young shoots densely floccose-tomentose, setulose-glandular or eglandular. Leaves narrowly elliptic to oblong or elliptic, (3.5—)6—11 x(l-)1.5-2.7cm, 3.3-4.5(-6) x as long as broad, apex ± acute, apiculate, base cuneate to ± rounded, upper surface glabrous, lower surface with a floccose, rufous, usually patchy (rarely ± continuous) ramiform tomentum, lower epidermis glaucous-papillate; petioles 0.7-1.5cm,.floccose-tomentose, usually eglandular (rarely setulose-glandular). Inflorescence 4-7-flowered; rhachis 2-3mm; pedicels c.lOmm, tomentose, eglandular. Calyx l-4mm, lobes rounded, sparsely tomentose to glabrous, margins ciliate. Corolla tubular-campanulate, usually crimson to scarlet, occasionally yellowish to pink, 30-40mm. Ovary densely stellate-tomentose, eglandular, tapering into the glabrous style. Capsule 10-25 x 4-5mm, straight to curved.

Habitat: Cliffs, Rhododendron scrub

Distribution: China (SE Xizang & adjacent NW Yunnan)

Altitude: 2750-3950m

Illustrations:

Notes

Plants apparently intermediate between R. floccigerum and R. sperabile var. sperabile occur in SE Xizang (outside the range of var. sperabile) and around Wei-hsi in NW Yunnan. These are characterised by their glandular shoots and narrow leaves, usually with a thick rufous indumentum. Over most of their respective ranges the two taxa remain distinct so the status of these intermediates remains uncertain.

Several fruiting specimens have been tentatively assigned to R. floccigerum but differ in their setulose-glandular petioles and young shoots and in their shorter leaves, 4-6cm long, that are usually glabrous by maturity and sometimes epapillate. In the absence of flowering material their status remains doubtful though they may have affinities with R. neriiflorum rather than with R. floccigerum. They are as follows: Forrest 20305, 20321, 20877, 20855, 22808, 25640,25800,25831.

R. floccigerum is closely allied to R. neriiflorum and R. sperabile but may be recognized from both by its discontinuous floccose leaf indumentum.

Nomenclature

Type: China, NW Yunnan, Tsekou, dans la Vallee du Mekong, a Thra nu, Soulie 1014 (iso. E,K)

Flags

Occurs in Countries: CN Altitude Ranges: 2,000 - 3,000m: 3,000 - 4,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: crimson, pink, scarlet, yellow

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):410

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Rhododendron floribundum Franchet

Shrub or small tree, 2-5m. Leaves coriaceous, oblanceolate to elliptic, 10-18 x 3.2—5.5cm, 3—3.3 x as long as broad, apiculate, upper surface glabrous when mature, veins deeply impressed, lower surface with a bistrate indumentum more or less covering the veins, the lower layer adpressed and whitish, the upper loose and lanate, hairs ramiform, yellowish at first, becoming white or greyish, persistent; petioles l-2cm, tomentose. Inflorescence 7—12-flowered; rhachis 3-5mm; pedicels c.lOmm, densely tomentose. Calyx c.lmm, lobes minute. Corolla broadly campanulate, magenta-rose fading pale pink, with crimson flecks and a basal blotch, c.40mm. Ovary densely tomentose; style glabrous. Capsule 20-30 x c.lOmm, cylindrical, sometimes slightly curved.

Habitat: Woodlands

Distribution: China (Sichuan)

Altitude: 1300-2600m

Illustrations:

Notes

Closely allied to R. denudatum and R. farinosum (q.v.).

Nomenclature

Type: China, Sichuan, circa Moupine, v-vi 1869, Abbe David (iso. E, K).

Flags

Occurs in Countries: CN Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Hymenanthes Habit: Tree Fl. Colour: crimson, magenta, pink

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):320

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Rhododendron florulentum P.X.Tan

Shrub, c.2m; young shoots densely spreading-setulose and glandular-hairy. Leaves persistent, dimorphic, elliptic; spring leaves 3.5-8.5 x I.2-4.5cm, 2.2-3 x as long as broad, apex acute to acuminate, base cuneate, margin entire, upper surface becoming greyish-setulose, lower surface with a ± dense reddish-brown setulose indumentum; summer leaves smaller, 22-30mm, otherwise as for spring leaves; petioles 5-IOmm, densely brownish-setulose. Inflorescence 7-14-flowered; pedicels 10-20 mm, densely brownish-strigose. Calyx minute, indumentum as for pedicels, lobes narrowly triangular to ± absent. Corolla tubular-campanulate, reddish purple to rose, c.25mm; tube 14-16 x 2-3mm, glabrous; lobes 8-10mm. Stamens 5, filaments glabrous or puberulent below. Ovary densely brownish-strigose; style glabrous. Capsule 5-8mm, ovoid, densely brownish-strigose.

Habitat: Open woodland

Distribution: China (E Guangdong, S Hunan, W Fujian).

Altitude: Around 1100m

Notes

R. hepaticum differs from R. florulentum only in the somewhat larger leaves and is thus treated here as a synonym.

The discoloured leaves that are used to separate R. piceum from the other two species may well be due to different drying techniques and are not of any taxonomic value.

Nomenclature

Type: China Fujian, Longyan Xian, Yen-Chung, 10 v 1974, L. G. Li (L. K. Lee) 740501 (holo. Inst. Mat. Med. Fujian).

Synonymy: R. hepaticum P.X.Tan, Survey Gen. Rhododendron S. China 98, f.3 (1983). Type: China, Guangdong, Jiaoling Xian, Shek- 104 EDINB. J. BOT. 47(2) wu Chuen, Tafong Chang, 1100m, 9 v 1957, L. Teng 4669 (holo. IBSC). R. piceum P.X.Tan, Bull. Bot. Res. N.E. Forest. Inst. 2(4): 83 (1983). Type: China, Fujian, Sanming Xian, Shiao-Hu, 20 iv 1964, Fujian Forestry Coll. (Silvicul Fok.) 86 (holo. IBSC).

Flags

Occurs in Countries: CN Altitude Ranges: 1,000 - 2,000m Subgenus: Tsutsusi Habit: Non-Tree Fl. Colour: purple, red, rose

Chamberlain, D.F. & Rae, S.J. (1990) A Revision of Rhododendron IV Subgenus Tsutsusi. Edinburgh Journal of Botany 47(2):103

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Rhododendron flumineum Fang & M.Y. He

Shrub, 2-3m; young shoots densely adpressed-strigose. Leaves persistent, chartaceous, dimorphic; spring leaves elliptic, 5.7-9 x 2.3-3cm, 2.3-2.5(-3) x as long as broad, apex acute to cuspidate, both surfaces with scattered adpressed hairs on lamina, hairs more dense on midrib; summer leaves (12-)25-30 x (8-)14-15mm; petioles 6-8mm, adpressed-strigose. Inflorescence 3-7-flowered; pedicels 4-8mm, densely golden-brown-strigose. Calyx c.lmm, strigose. Corolla funnel-campanulate, pinkish white to red, with darker flecks, c. I8mm; tube c.9mm, 3mm broad at base, 6mm broad below lobes, glabrous on outer surface. Stamens 5, filaments glabrous. Ovary densely strigose; style strigose towards base. Capsule c,7 x 2.5mm, ovoid, strigose.

Habitat: Mixed forest

Distribution: China (S Yunnan)

Altitude: 1400-1750m

Notes

Closely allied to R. rufohirtum but differing in the greater number of flowers per inflorescence and in the adpressed-hairy indumentum on the shoots.

Nomenclature

Type: China, Yunnan, Jinping Xian, 1800m, 30 iii 1958, Q. Huang 291 (holo. PE)

Flags

Occurs in Countries: CN Altitude Ranges: 1,000 - 2,000m Subgenus: Tsutsusi Habit: Non-Tree Fl. Colour: pink, red, white

Chamberlain, D.F. & Rae, S.J. (1990) A Revision of Rhododendron IV Subgenus Tsutsusi. Edinburgh Journal of Botany 47(2):101

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Rhododendron formosanum Hemsley

Shrub or small tree, 2-5.5m. Leaves narrowly elliptic to oblanceolate, 7-13 x 1.5-2.5cm, 4.5-5.5 x as long as broad, apex acute, glabrous above, with a compacted fawn indumentum beneath intermixed with a few glands; petioles l-2cm, floccose at first, soon glabrescent. Inflorescence 10-20-flowered; rhachis 15-20mm; pedicels 10-30mm, densely rufous-tomentose. Calyx c.lmm, tomentose, lobes minute. Corolla widely funnel-shaped, white to pink, with purplish flecks, 30-40mm. Ovary densely rufous-tomentose; style glabrous. Capsule not known.

Habitat: Broad-leaved forests

Distribution: Taiwan

Altitude: 800-2000m

Illustrations:

Nomenclature

Type: Taiwan, South Cape, Henry 1976 (iso. BM, K).

Flags

Occurs in Countries: TW Altitude Ranges: 0 - 1,000m: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Hymenanthes Habit: Tree Fl. Colour: pink, white

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):324

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Rhododendron formosum Wallich

Erect shrub to 2 m. Young growth loriform-setose. Leaves narrowly elliptic to linear-elliptic or linear-obovate, long-tapering to the base, acute or acuminate at the apex, (26-)42-72 x 10-21 mm, not more than 21 mm broad, the blade narrowly decurrent on the petiole, upper surface dark green, elepidote, margin loriform-setose when young, some, at least, of the setae persisting, lower surface lepidote with unequal scales about their own diameter apart; petioles loriform-setose. Inflorescence 2-3-flowered, pedicels lepidote. Calyx disc-like, lepidote, weakly loriform-ciliate. Corolla white or white flushed pink, often with a yellow blotch and pink markings along the tube, openly funnel-campanulate, 40-55 mm, the tube 24-30 mm, pilose at the base and variably lepidote outside. Stamens 10, filaments pubescent towards the base. Ovary lepidote, style impressed, lepidote to well above the base. Capsule c. 16 mm, lepidote.

Notes

A rather variable and geographically scattered species, divisible into two varieties

Flags

Occurs in Countries: IN Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Rhododendron Habit: Non-Tree Fl. Colour: pink, white, yellow

Cullen, J. (1980) A Revision of Rhododendron 1: Subgenus Rhododendron sections Rhododendron & Pogonanthum. Notes from the Royal Botanic Garden Edinburgh 39(1):46

Rhododendron formosum var. formosum

Leaves 10-16 mm broad

Habitat: Hillsides

Distribution: India (Meghalaya)

Altitude: 1450-2300m

Illustrations:

  • Ic: Gartenflora 9: t. 277 (1860)
  • Bot. Mag. 177: t. 563 (1969-70)
Nomenclature

Type: Described from 'Assam, Khasia Hills, 3-5000 ft'

Synonymy: R. gibsoni Paxton, Mag. of Bot. 8: t. 217 (1841). Type: a cultivated specimen (n.v.). R. formosum var. salicifolium C. B. Clarke, Fl. Brit. India 3:473 (1882). Described from the Khasia Hills. R. iteaphyllum Hutchinson, Notes R.B.G. Edinb. 12:83 (1919). Syntypes: Assam, Khasia Hills, rocks of Bor-Panee, 2000 ft, 24 vii 1850, Hooker & Thomson (K); along the stream at the same place, Simons (K); without locality, Lobb 3 and G. Mann (both K)

Rhododendron formosum var. inaequale (Hutchinson) Cullen

Leaves 15-21 mm broad

Habitat: Hillsides

Distribution: India (Meghalaya, Manipur, Arunachal Pradesh)

Altitude: 1450-2230m

Illustrations:

  • Bot. Mag. 171: t. 295 (1956-7)
Nomenclature

Synonymy: R. inaequale Hutchinson, Notes R.B.G. Edinb. 12:75 (1919). Type: India, Kollong, 6000 ft, 23 viii 1885, Clarke 40025 (holo. K)

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Rhododendron forrestii [Balfour f. ex] Diels

Dwarf creeping shrub; stems up to 0.6m long though rarely more than 0.1m high; perulae persistent. Leaves obovate to orbicular, 1-2.8 x 0.9-1.8cm, 1.1—2.5(—3.2) x as long as broad, apex rounded to retuse, sometimes mucronate, base broadly cuneate, often narrowly decurrent, upper surface glabrous, lower surface glabrous or with a few stipitate glands and branched hairs towards the base, green to purple or glaucous-papillate below when mature; petioles 0.5-0.8cm, stipitate-glandular and sparsely floccose-tomentose. Flowers solitary; pedicels 10-20mm, stipitate-glandular. Calyx c.lmm, lobes fleshy. Corolla fleshy, tubular-campanulate, crimson, 30-35mm. Ovary densely stipitate-glandular and rufous-tomentose. Capsule 15-20 x 6-7mm.

Habitat: Moist stony pasture, on boulders

Altitude: 3050-4500m

Notes

20*. ? R. forrestii x haematodes. Syn: R. chaetomallum Balfour f. & Forrest var. chamaephytum Cowan, Notes R.B.G. Edinb. 21: 146 (1936). Type: China, Xizang, Singo Samba, Lo La Chu, 16 v 1936, Ludlow, Sherriff & Taylor 3786 (holo. BM; iso. E, fragm.). Prostrate shrub, 0.3-0.6m. Leaves obovate, c.4.5 x 2.2cm, apex rounded, base cuneate, lower surface with traces of a red-brown floccose indumentum; petioles very short. Inflorescence few-flowered. Calyx c.7mm, cupular, irregular, red, glabrous. Corolla tubular-campanulate, fleshy, deep crimson, c.35mm. Ovary densely rufous-tomentose. CHINA (S Xizang). Scrambling over rocks in Abies/Rhododendron forest, 3950m. Apparently a hybrid between R. forrestii (or possibly R. chamaethomsonii) and R. haematodes. Field studies are however required to confirm the status of this plant.

Flags

Occurs in Countries: CN Altitude Ranges: 3,000 - 4,000m: 4,000 - 5,000m Subgenus: Hymenanthes Habit: Non-Tree Fl. Colour: crimson

Chamberlain, D.F. (1982) A Revision of Rhododendron II. Subgenus Hymenanthes. Notes From the Royal Botanic Garden Edinburgh 39(2):407

Rhododendron forrestii subsp. forrestii

Notes

Plants in which the juvenile state, with leaves purple below, persists to maturity, have been referred to R. forrestii sensu stricto. These may be no more than local ecotypes and are not worthy of formal taxonomic recognition. The more usual form with leaves green below at maturity has been referred to R. forrestii var. repens.

Kingdon-Ward 9816, from the Adung Valley in NE Burma, has sulphur-yellow flowers but otherwise matches subsp. forrestii.

Three plants from S Xizang, Ludlow & Sherriff 1883, 3942, 4751, have the growth form, small leaves, scarlet to crimson flowers and densely tomentose ovaries of subsp. forrestii but differ in their 3-4-flowered inflorescence. The status of these plants is uncertain, particularly as they come from an area outside the range of the species (see Map 121).

Nomenclature

Type: China, NW Yunnan, ascent of the Tsedjiong Pass, Mekong/Salween divide, 10-11000ft, vii 1905, Forrest 699 (holo. E).

Synonymy: R. repens Balfour f. & Forrest, Notes R.B.G. Edinb. 11:115 (1919). Type: China, W NW Yunnan, Mekong/Salween divide, 28°20'N, 12-14000ft, vi 1917, Forrest 14011 (holo. E). R. forrestii Diels var. repens (Balfour f. & Forrest) Cowan & Davidian, Rhododendron Yearbook 6: 69 (1951). Ic: Bot. Mag. 153: t.9186 (1929).

Rhododendron forrestii subsp. papillatum Chamberlain

Distribution: China (S Xizang)

Notes

Subsp. papillatum apparently intergrades with R. chamaethomsonii, especially on Doshong La and Deyang La. Intermediates include: Ludlow, Sherriff & Elliot 13278, 13783, 15070, 15098, 15170, 15285, 15292, 15400 and Kingdon- Ward 5846 (E), the type of R. forrestii Diels var. tumescens Cowan & Davidian (NotesR.B.G. Edinb. 26: 69, 1951). One specimen, L.} S. &E. 15013, is apparently a hybrid between subsp. papillatum and R. campylocarpum.

Nomenclature

Type: China, S Xizang, Doshong La, 11-13000ft, 24 vi 1924, Kingdon-Ward 5845 (holo. E; iso. K).

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Rhododendron fortunans J.J.Sm.

Shrub to 2m. Twigs c.1.5mm in diameter, densely and persistently brown-scaly; internodes 2–7cm. Leaves 3–5 together in a loose pseudowhorl, or, especially the smaller ones, spirally and evenly arranged along the stems. Blade 25–130 x 6–40mm, narrowly elliptic to elliptic; apex acute or acuminate, the extreme tip rounded; margin revolute especially in the smaller leaves; base acutely tapering, scaly on both sides initially, silvery-scaly but glabrescent above with age although leaving dark pits from scale attachments; beneath completely covered with overlapping brown scales. Scales very variable in size, the largest c.0.2mm in diameter, with pale brown, broad flanges and large, dark brown, centres. Mid-vein very broad beneath, gradually decreasing distally; lateral veins 5–10 per side, wide-spreading almost to a right angle or in small leaves not visible, clearly anastomosing; distinctly impressed above, prominent beneath, with lax reticulation; lamina markedly rugose. Petiole 5–12 x 2–3mm, grooved above, somewhat flattened, densely scaly. Flower buds ovoid, large. Bracts to 24 x 12mm, ovate to obovate-spathulate, the outer ones all over finely hairy, scaly in the upper outer part, the inner ones scaly only externally, all fringed with simple white hairs. Bracteoles to 16mm, linear below, spathulate distally, ciliate. Inflor­escence of 10–13 flowers in a complete or open umbel. Pedicels 15–20mm, thick, densely scaly. Calyx oblique, small, cup-shaped, shortly obtusely 5-lobed, densely scaly. Corolla 15 x 20mm, widely funnel-shaped, white, without scent; tube 3–6 x 3 x 6mm, shortly funnel-shaped, very densely brown-scaly, densely hairy inside except where the filaments are inserted; lobes 9–12 x 9–12mm, glabrous inside, brown-scaly in the lower ½ outside. Stamens c.9mm; filaments white, linear, glabrous at the very base then hairy to the apex; anthers c.3mm, purple-brown, the cells divergent below, each bearing a basal conical obtuse lobe. Disc glabrous. Ovary 2.5 x 1.7mm, conical, densely scaly, gradually tapering distally; style 2.5mm, thick, glabrous; stigma thick, rounded. Fruit brown, shortly cylindrical, 18–23 x 3mm.

Distribution: Indonesia, C Borneo, top of Bukit Raya in the Schwaner Mts

Altitude: 1500-2300m

Notes

Latin – fortunatus – prosperous, lucky or happy; presumably the collector was happy to find such an attractive plant.

This is an interesting species repeatedly collected on Bukit Raya but not yet introduced into cultivation. The flowers are, as far as can be compared from dry specimens, identical with those of R. himantodes but the leaves are markedly different. They are not linear in shape, but elliptic and markedly rugose, with very prominent lateral veins which give R. fortunans a very different appearance to that of R. himantodes. The very wide range of leaf sizes in different specimens of this species is curious and field observations are needed to explain these differences.

Nomenclature

Type: Molengraaf 3436 B, 6 Oct. 1984. Indonesia, (Borneo), Central Kalimantan, Schwaner Mts, B. Raja (BO, L).

Flags

Occurs in Countries: ID Altitude Ranges: 1,000 - 2,000m: 2,000 - 3,000m Subgenus: Vireya Habit: Non-Tree Fl. Colour: brown, white

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:116

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Rhododendron fortune Lindley

Shrub or tree, 3-10 m. Leaves broadly oblanceolate to obovate, 8-18 x 2.5-6cm, 1.7-4 x as long as broad, apex ± acute to rounded and mucronate, base rounded, lower surface glabrous except for persistent punctulate hair bases; petioles 1.2-3