糙皮桦 cao pi hua

Betula albosinensis Burkill var. septentrionalis C. K. Schneider; B. bhojpattra Lindley in Wallich; B. bhojpattra var. latifolia Regel; B. utilis var. prattii Burkill.

Trees to 35 m tall; bark dark red-brown, exfoliating in thin flakes. Branches red-brown, glabrous; branchlets brown, densely resinous glandular and pubescent. Petiole 0.8-2 cm; leaf blade ovate, ovate-elliptic, or oblong, 4-9 × 2.5-6 cm, abaxially densely resinous punctate and pubescent, bearded in axils of lateral veins, adaxially densely villous when young, base rounded or subcordate, margin irregularly and doubly mucronate serrate, apex acuminate or caudate-acuminate; lateral veins 8-14 on each side of midvein. Female inflorescence 1, or 2 or 3 in a raceme, pendulous, oblong-cylindric, 3-5 cm × 7-12 mm; peduncle 0.5-1.5 cm; bracts 5-8 mm, pubescent, ciliate, 3-lobed, middle lobe lanceolate, lateral lobes ovate, ca. 1/3 as long as middle lobe. Nutlet obovate, 2-3 × 1.5-2 mm, with membranous wings ca. as wide as nutlet. Fl. Jun-Jul, fr. Jul-Aug. 2n = 56.

Temperate broad-leaved forests; 2500-3800 m. Gansu, Hebei, Ningxia, Qinghai, Shaanxi, W Sichuan, E and S Xizang, NW Yunnan [Afghanistan, Bhutan, India, Nepal]

A valuable timber tree of commercial importance. The wood is hard, dense, and rather brittle, with the heartwood pinkish or light reddish brown, with a silky luster.