Description from Flora of China
Annual or perennial herbs, glabrous to pubescent. Stems erect to ascending or prostrate. Leaves pinnately 3-foliolate or palmately 3(or 5-9)-foliolate; stipules entire or toothed, partly adnate to petiole; leaflets toothed or entire. Inflorescences axillary or terminal. Flowers sessile or shortly pedicellate, in heads, short racemes, umbels, or rarely solitary; bracts small or absent, often connate into a dentate and membranous involucre. Calyx 5-10[-30]-veined, regular or bilabiate, after flowering sometimes strongly inflated; teeth equal or unequal. Corolla persistent, white, pink, purple, or yellow, sometimes inflated in fruit. Filaments some or all dilated at apex; anthers uniform. Ovary with 1-12 ovules. Legume indehiscent, enclosed by marcescent calyx and petals. Seeds 1 or 2(-9), ovoid to spherical or reniform.
About 250 species: temperate and subtropical Africa, America, Asia, and Europe; 13 species (nine introduced) in China.