越南黄牛木 yue nan huang niu mu

Shrubs or trees, deciduous, 3-6 m tall. Trunk with spreading, long thorns on lower part. Bark exfoliating in flakes. Twigs somewhat compressed, ± tetragonous when young, becoming terete; interpetiolar scars interrupted. Petiole 5-7 mm, glabrous; leaf blade abaxially greenish, adaxially green, elliptic to oblong, 4-10 × 2-4 cm, abaxially with pellucid glands, midvein raised abaxially, impressed adaxially; secondary veins 8-10 pairs, broadly spreading, anastomosing regularly near leaf margin; tertiary veins and veinlets reticulate, base rounded, apex obtuse or acute. Cymes 5-8-flowered, in axils of fallen leaves. Pedicels 3-5 mm. Flowers ca. 1.3 cm in diam. Sepals elliptic or oblong-lanceolate, 5-6 × 2-3 mm, apex obtuse. Petals obovate or obovate-oblong, 1.1-1.5 cm, ciliolate and brown-glandular on upper half of margin, narrowly clawed at base; petal-scale indistinct, ca. 2 mm, base cuneate, apex truncate and denticulate. Stamen fascicles ca. 1 cm, with 20-30 stamens; filament ca. as long as stalk; connectives with glands or not. Fasciclodes ligulate, 1-1.5 mm, attenuate. Ovary narrowly conic, ca. 4 mm, glabrous; styles ca. 3.5 mm. Capsule dark brown, oblong, 0.6-1.5 cm, up to 1/2 enclosed by persistent calyx. Seeds 6-8 per locule, 3-7 mm. Fl. Mar-Apr, fr. after May.

Thickets, open secondary forests; below 1000 m. S Guangxi, Hainan, S Yunnan [Cambodia, Indonesia, Laos, Malaysia, Myanmar, Philippines, Thailand, Vietnam].