Rhododendron sinogrande, Balf. f. et W. W. Sm., var. boreale, Tagg et Forrest. Var. nov.
Varietas haec septentrionalis foliis minoribus magis coriaceis, iloribus pallido-luteis inter signa alia minora a typo recedit.
Among Mr. Forrest's 1922 collection from Tsarong are forms of Rh, sinogrande which represent a northern extension of the southern Salween Valley type. There is no doubt about their affinity. They
are very near to Rh. sinogrande but are not the typical southern form. Apart from foliage differences?the leaves of the northern forms are somewhat more leatheiy, have a slightly denser under-leaf indumentum commonly olive-grey, not grey-white, and the broadest part of the lamina is generally nearer the leaf apex?the chief characteristics of the northern forms are larger flowers of better colour. Mr. Forrest's comment on his 21705 is, " a grand species but leaning towards coarseness. Flowers a shade lighter than the best forms of Rh. lacteum." Of 21705A he says, " Flowers clear pale-yellow with a crimson blotch at base " and " A fine species with flowers of a clearer yellow than 21705." The flowers of the southern type are described as dull white." Mr. Forrest when he collected 21705 and 21705A suggested that they were distinct species not previously gathered by him, but until more is known of them in cultivation I think they should be regarded as geographical varieties of Rh. sinogrande.
S.E. Tibet. Tsarong, West of Chamatong, Salween-Kiu Chiang divide. Lat. 28? 18' N. Long. 98? 27' E. Alt. 13-14,000 ft. Shrub of 20-25 ft. Flowers fleshy soft yellow throughout without markings. In Rhododendron forest. June 1922. G. Forrest. No. 21705.
S.E. Tibet. Tsarong, Londre-la, Salween-Mekong divide. Lat. 28? 14' N. Long. 98? 40' E. Alt. 12-13,000 ft. Shrub of 20 ft. Flowers fleshy clear pale yellow with a crimson blotch at base. In Rhododendron thickets and forests. May 1922. G. Forrest. No. 21705A.
S.E. Tibet. Tsarong. Duplicate in fruit of No. 21705. Same locality and situation. October 1922. G. Forrest. No. 22761.