Betula wilsonii Bean.

Shrubs or trees to 5 m tall; bark grayish brown. Branches decumbent and prostrate or slender and pendulous; branchlets brown, very slender, densely yellow or white pubescent. Bud scales glabrous. Petiole 3-5 mm, densely yellow villous; leaf blade ovate-lanceolate or oblong-lanceolate, 2-2.5 × 1-2.5 cm, leathery, abaxially densely yellow-brown or white sericeous-villous along veins, adaxially densely villous when young, base rounded, margin acutely doubly serrate, apex acuminate or acute; lateral veins 9-21 on each side of midvein, distinctly raised abaxially, deeply impressed adaxially. Female inflorescence oblong-cylindric, 1-2 cm × 5-6 mm; peduncle ca. 2 mm, densely yellow villous; bracts 4-5 mm, densely pubescent and ciliolate, 3-lobed, middle lobe ovate-oblong, with a tuft of long hairs at apex, lateral lobes ovate, slightly shorter than middle lobe. Nutlet obovate, ca. 1.5 × 1 mm, pubescent, with very narrow wings. Fl. May-Jun, fr. Jul-Aug.

* Thickets on moist cliffs; 1900-3100 m. SE Gansu, Shaanxi, N and W Sichuan