坚桦 jian hua

Betula ceratoptera G. H. Liu & Y. C. Ma; B. chinensis var. angusticarpa H. Winkler; B. chinensis var. nana Liou; B. exalata S. Moore; B. jiaodongensis S. B. Liang; B. liaotungensis Baranov.

Shrubs to 5 m tall; bark black-gray. Branchlets brown or yellow-brown, densely villous. Petiole 0.2-2 cm, densely villous; leaf blade ovate, broadly ovate, or ovate-elliptic, 1.5-6 × 1-5 cm, abaxially villous, sometimes resinous punctate, sparsely bearded in axils of lateral veins, adaxially densely villous when young, base rounded or broadly cuneate, margin irregularly and doubly dentate-serrate, apex acute or obtuse; lateral veins 8 or 9(or 10) on each side of midvein. Female inflorescence subglobose, rarely oblong, 1-2 × 0.6-1.5 cm; peduncle 1-2 mm; bracts 5-9 mm, pubescent, ciliate, 3-lobed, lobes reflexed, middle lobe lanceolate, lateral lobes spreading, ovate, 1/3-1/2 as long as middle lobe. Nutlet obovate or ovate, with very narrow wings, sometimes horn-shaped at apex. Fl. May-Jun, fr. Jul-Aug.

Broad-leaved forests in mountain valleys, shaded, rocky mountain slopes; 700-3000 m. E Gansu, Hebei, Henan, Liaoning, Nei Mongol, Shaanxi, Shandong, Shanxi [Korea]

This species is one of the most valuable timber trees in N China. The wood is extremely hard and dense, close grained, very fine textured, and is used for making pestles and wagon axles.