Description from Flora of China
Trees or small trees, to 25 m tall. Branchlets purplish brown or grayish green when bark falls off, slightly ribbed, with scattered whitish lenticels, smooth and glabrous. Spines purplish brown to brownish black, slightly flat, robust, 2-15.5 cm, often branched. Leaves pinnate or bipinnate (pinnae 2-6 pairs), 11-25 cm; petiolules very short; leaflets 3-10 pairs, adaxially sometimes shiny, ovate-oblong or ovate-lanceolate to oblong, 2-7(-9) × 1-3(-4) cm (leaflets of bipinnate leaves obviously smaller), papery to thickly papery, abaxially puberulent on midvein and at base, glabrescent when old, adaxially puberulent or glabrous, slightly scabrous, reticulate veinlets obscure, base broadly cuneate or rounded, slightly oblique, margin entire or repand-crenate, apex rounded, sometimes emarginate. Flowers yellowish green, in axillary or terminal, puberulent spikes. Male inflorescence 8-20 cm; female inflorescence 5-16 cm. Male flowers: 5-6 mm in diam.; receptacle deep brown, ca. 1.5 mm, outside densely brown puberulent; sepals 3 or 4, triangular-lanceolate, ca. 2 mm, both surfaces pubescent; petals 4, elliptic, ca. 2 mm, pubescent; stamens 6-8(or 9). Female flowers: 5-8(-9) mm in diam.; receptacle ca. 2 mm; sepals and petals 4 or 5, similar to those of male flowers in shape, ca. 3 mm, both surfaces densely pubescent; staminodes 4-8; ovary glabrous; ovules numerous; style short, incurved; stigma inflated, 2-lobed. Legume brown or brownish black, compressed, strap-shaped, 20-54 × 2-7 cm, irregularly twisted or falcate, apex with beak 5-15 mm; stipe 1.5-3.5(-5) cm; valves leathery, often bullate, glabrous or velutinous, shiny. Seeds numerous, deep brown, elliptic, 9-10 × 5-7 mm, smooth. 2n = 28*.
Sunny slopes, valleys, streamsides, near roads, forests; 100-2500 m. Anhui, Guizhou, Hebei, Henan, Hunan, Jiangsu, Jiangxi, Liaoning, Shandong, Yunnan, Zhejiang [Japan, Korea].