Trees or shrubs, usually unarmed, rarely scandent and with short, recurved hooks. Leaves bipinnate; stipules usually small, rarely larger and caducous; petiole and rachis with glands; leaflets small in numerous pairs or larger in few pairs. Inflorescences of globose heads, arranged in axillary or terminal panicles. Flowers bisexual. Calyx campanulate or funnel-shaped, 5-toothed. Corolla funnel-shaped, upper part 5-lobed. Stamens numerous, connate into a tube at base, free part of filaments long exserted; anthers small. Central flowers of heads with broader calyx and much longer filament tube. Ovary flattened; style long, slender; stigma minute. Legume broadly linear or oblong, straight, plano-compressed, indehiscent, or dehiscent along both sutures, continuous inside. Seeds ovoid or orbicular, compressed, funicle filiform.

Between 120 and 140 species: tropical to warm regions of the world; 16 species (two endemic, two introduced) in China.