Description from Flora of China
Herbs or subshrubs, prostrate or twining. Leaves pinnately 3-foliolate, rarely 1-7-foliolate; stipules small, deciduous or persistent; stipels persistent. Racemes axillary; rachis with remote and slightly swollen nodes; bracts small, setaceous; bracteoles minute. Flowers solitary, paired, or several clustered at nodes of rachis. Calyx lobes linear or lanceolate, upper 2 entirely connate into 1, lateral slightly smaller, lowest often longest. Corolla slightly exserted; petals subequal in length; standard orbicular, ovate, or obovate-orbicular, margin slightly inflexed or appendaged; wings narrow or obovate, adherent to keel; keel obtuse and almost straight, subequal to or longer than wings. Stamens diadelphous; vexillary stamen free or connate from middle downward; anthers uniform. Ovary subsessile; ovules numerous; style filiform, glabrous; stigma small, capitate, terminal. Legumes linear, compressed, straight or slightly incurved, ± septate between seeds. Seeds small, compressed, estrophiolate.
About 60 species: tropical and subtropical Asia, Africa, and America; two species in China.
(Authors: Chen Dezhao (陈德昭 Chen Te-chao), Zhang Dianxiang (张奠湘); Mats Thulin)