An evergreen shrub 4 to 9 ft high; young wood slightly scaly. Leaves aromatic, oval-lanceolate, tapering about equally to each end, 11⁄2 to 21⁄2 in. long, 3⁄8 to 5⁄8 in. wide, bright green and slightly scaly above, densely scaly beneath, the scales yellowish; stalk 1⁄8 in. long. Flowers produced during May in terminal and axillary clusters of six to eight; pedicels about 3⁄4 in. long, scaly. Calyx minute. Corolla of a pale blush tint with two groups of brown spots on the upper side, up to 11⁄2 in. across, flat, open, short-tubed. Stamens ten, pinkish white, hairy at the base, anthers dark red. Ovary scaly; style glabrous. (s. Triflorum ss. Yunnanense)
Native of Yunnan, S.W. Szechwan, and Kweichow; probably first introduced by Forrest. It belongs to the same group as R. yunnanense, and its flowers are equally pretty. But the leaves are never bristly above, as they often are in R . yunnanense, they are more scaly beneath, the stamens are not so much protruded beyond the corolla as in that species; the flowers are smaller and earlier. It frequently produces a considerable number of flower clusters densely packed at the end of the shoot.
R. siderophyllum received an Award of Merit when shown by Edmund de Rothschild, Exbury, on March 20, 1945.