Description from Flora of China
Herbs or shrublets. Stems herbaceous or often slightly woody, bristly to glabrescent. Stipules spurred below point of insertion, scarious, persistent, basal portion 1- or 2-auriculate. Leaves opposite, paripinnate, subsessile, few to 12-foliolate, sensitive; rachis often ending in a spine; leaflet blades usually linear-oblong, bristly on abaxial side and margins, apex mucronate. Inflorescences axillary, dense racemes or ± scorpioid cymes, sometimes reduced to a solitary flower; bracts stipule-shaped, scarious, striate, caducous. Flowers small. Bracteoles scarious, persistent. Hypanthium short, much reduced. Calyx membranous or scarious, persistent and often accrescent at fruit, 2-lipped, lips usually entire. Corolla white, purple, yellow, or blue, longer than calyx; standard orbicular to oblong; wings and keel almost as long as standard; keel inflexed, lateral appendages nearly as long as claws, apex blunt. Stamens usually diadelphous (5+5); anthers uniform. Intrastaminal disk present. Ovary linear, with numerous ovules; style filiform, inflexed, persistent to fruit; stigma terminal, small. Legume a loment, plicate within calyx, shortly stipitate, with few to many articles. Seeds orbicular or reniform, compressed; hilum eccentric.
About 20 species: tropics of Asia and Africa; five species in China.