Description from Flora of China
Trees. Branches spreading, glabrous to pubescent. Leaves alternate, imparipinnate; stipules small, caducous; stipels absent; leaflets alternate, rarely subopposite. Inflorescence a simple raceme to a lax, terminal or axillary panicle. Flowers yellow; bracts and bracteoles small, caducous. Pedicel articulate. Calyx often incurved, obconical, 5-toothed; teeth short, upper 2 ± connate. Corolla papilionaceous, exserted beyond calyx; petals long clawed; standard ovate to orbicular, as keel crisped on margin. Stamens 10, monadelphous to diadelphous (5+5 or 9+1), staminal sheath split open dorsally; anthers versatile. Ovary stipitate or sessile, 2-6-ovuled; style incurved, filiform, glabrous; stigma terminal. Legume indehiscent, orbicular, compressed, broadly hardened winged around margin, usually 1-seeded; style persistent, incurved. Seeds oblong or subreniform, hilum small.
About 30 species: pantropical with the exception of Australia, with the greatest diversity in Africa; one species in China.