An evergreen shrub 4 to 12 ft high, or occasionally a small tree up to 25 ft high; branchlets clad with a brown to fawn-coloured or whitish tomentum. Leaves mostly oblong-elliptic or oblong-lanceolate, 2 to 31⁄2 in. long, 11⁄2 to 2 in. wide, acute to acuminate at the apex, loosely tomentose above at first, becoming more or less glabrous, underside coated with a thin brown suede-like indumentum made up of long-rayed hairs; petiole about 1⁄2 in. long. Flowers up to about sixteen in an umbellate cluster, opening in April or May. Calyx minute. Corolla between funnel-shaped and campanulate, about 13⁄4 in. wide, white to pink or creamy white, spotted or unmarked. Ovary narrow-cylindric, usually glabrous or nearly so; style glabrous or slightly downy at the base. (s. Lacteum)
R. dryophyllum occurs, often at high altitudes, from S.W. Szechwan (Muli area) across N.W. Yunnan to the Tibetan Himalaya, where it has been collected not far from the eastern frontier of Bhutan; it has also been found in the Seinghku valley, N.W. upper Burma. It was introduced by Forrest.
R. dumulosum Balf. f. & Forr. – Differing from R. dryophyllum only in its constantly dwarf habit and smaller leaves.
R. phaeochrysum Balf. f. & W. W. Sm. – Similar to R. dryophyllum and with more or less the same distribution, but with the ovary always completely glabrous and the indumentum of the leaves beneath tending to be agglutinate, i.e., with the hairs more or less glued together by a resinous secretion. Wing-Cdr F. L. Ingall of Corsock, Stranraer, won the McClaren Cup for a truss from his fine form of R. phaeochrysum when he exhibited it at the Rhododendron Show in 1964 (R.C.Y.B. 1965, fig. 10). R. agglutinatum Balf. f. & Forr. is in turn closely allied to R. phaeochrysum and linked to it by intermediates, but typically has smaller leaves and flowers (Cowan and Davidian, R.C.Y.B. 1956, pp. 146-7).
From the Supplement (Vol. V)
See R. phaeochrysum in this supplement.