Description from Flora of China
Usually vines, creeping or twining, rarely erect shrubs or subshrubs. Leaves pinnately 3-foliolate; stipules usually caducous; stipels persistent or absent; leaflets usually with sessile glands abaxially. Inflorescence axillary, racemose, sometimes branched or 1-flowered. Bracts usually deciduous, rarely persistent. Calyx campanulate, 5-lobed, upper 2 lobes ± connate, lowest 1 longer. Corolla longer than calyx or short; standard circular or obovate, base with inflexed auricles, with or without appendage; wings and keels subequal, inflexed. Stamens diadelphous; vexillary stamen free; anthers uniform. Ovary sessile or subsessile; ovules (1 or)2; style curved above middle, usually hairy at lower part; stigma terminal. Legume oblong, oblanceolate, obovoid-ellipsoid, obliquely orbicular, sickleform, or ellipsoid, dehiscent, compressed or inflated, (1 or)2-seeded, not septate, apex always beaked. Seeds (1 or)2, usually suborbicular or reniform; hilum round, funicle in middle, strophiole small or absent.
About 200 species: worldwide; 13 species (five endemic) in China.
(Authors: Sa Ren (萨仁); Michael G. Gilbert)