Herbs, diffuse, shrubby, to 1 m tall. Stems cylindric, branched, with reflexed bristles and scattered, curved prickles. Stipules lanceolate, 5-10 mm, bristly; pinnae and leaflets sen­sitive; pinnae usually 2 pairs, digitate, 3-8 cm; leaflets 10-20 pairs, linear-lanceolate, 6-15 × 1.5-3 mm, abaxially slightly hispid, adaxially glabrous, margin ciliate, apex acute. Heads solitary or 2, axillary, globose, ca. 1 cm in diam.; peduncle long; bracts linear. Flowers numerous, pink, small. Calyx mi­nute. Corolla campanulate; lobes outside pubescent. Stamens 4, exserted. Ovary shortly stipitate, glabrous; ovules 3 or 4; style filiform; stigma small. Legumes arranged in a star, slightly re­curved, flat, oblong, 1-2 cm × ca. 5 mm, consisting of 3-5 1-seeded segments which fall away from persistent, bristly su­tures. Seeds light brown, ovoid, ca. 3.5 mm. Fl. Mar-Oct, fr. May-Nov. 2n = 52*.

This plant is grown as an ornamental and used medicinally as a sedative and sleep aid.

Wilderness tracts, wastelands, or cultivated; sea level to 1500 m. Fujian, Guangdong, Guangxi, Hainan, Jiangsu, Taiwan, Yunnan, Zhe­jiang [native to tropical America; naturalized in tropical regions of the world].