Description from Flora of China
Perennial twining herbs. Leaves pinnately 3-foliolate; stipules and stipels deciduous. Flowers small, in axillary clusters or racemes; bracts small, linear, persistent; bracteoles linear, longitudinally striate. Calyx membranous, campanulate, 4- or 5-lobed. Corolla slightly exserted; standard obovate, narrow at base, clawed, without auricles; wings narrow, adnate to blunt, straight, and shorter keel. Stamens monadelphous, only 5 longer developed, 5 shorter sterile or lacking. Ovary sessile, many ovuled; style short, curved, glabrous; stigma capitate. Legumes linear, flattened, persistent style base forming upcurved beak at apex, sometimes transversely impressed between seeds. Seeds numerous.
About eight species: tropics of both hemispheres; one species in China.
(Authors: Sun Hang (孙航); Mats Thulin)