Description from Flora of China
Herbs, subshrubs, or shrubs. Leaves pinnately 3-foliolate or 1-foliolate by reduction of lateral leaflets, stipulate, stipellate. Flowers usually smaller, in racemes or panicles, axillary or terminal, rarely solitary or binate in leaf axils. Bracts persistent or early deciduous; bracteoles present or absent. Calyx campanulate, 4- or 5-lobed, bilabiate; upper 2 lobes connate for all or most of length, entire or 2-toothed at apex, lower lobes free, longest. Corolla white, green-white, pink, purple, or violet; standard elliptic or obovate to nearly orbicular; wings ± adherent to keel, wholly clawed. Stamens diadelphous (9+1), rarely monadelphous. Ovary usually sessile, with several to many ovules. Legume compressed, usually indehiscent, transversely segmented, upper (adaxial) suture slightly constricted or straight, lower (abaxial) one constricted; articles mostly ellipsoidal to quadrangular. Cotyledons epigeous.
About 280 species: mostly in subtropical and tropical regions; 32 species (four endemic, three introduced) in China.
(Authors: Huang Puhua (黄普华 Huang Pu-hwa); Hiroyoshi Ohashi)