Shrubs or trees, prickly or not. Leaves abruptly bipinnate; rachis very flattened; pinnae usually 2-4, appearing congested at first sight; stipules small, scaly to spinescent; rachis of pinnae very long and flattened; leaflets reduced, inconspicuous, numerous, oppo­site or alternate, small. Racemes or cymes axillary; bracts caducous, small. Pedicels long, without bracteoles. Flowers bisexual. Re­ceptacle discoid. Sepals 5, slightly unequal, imbricate or subvalvate, membranous. Petals 5, spreading, slightly unequal, shortly clawed, uppermost broader and long clawed. Stamens 10, free, not exserted; filaments villous at bases; anthers ovoid, versatile, cells opening by lateral slits. Ovary shortly stalked, inserted at bottom of receptacle, glabrous to ± pubescent, many ovuled; style filiform, glabrous or pubescent; stigma truncate, ciliate or glabrous. Legume linear, torulose, not winged, indehiscent, thinly leathery. Seeds oblong; hilum small, near apex, with endosperm; cotyledons flat, fleshy; radicle straight.

About four species: mostly in dry regions of S Africa, tropical America, and Oceania; one species (introduced) in China.

(Authors: Chen Dezhao (陈德昭 Chen Te-chao), Zhang Dianxiang (张奠湘); Kai Larsen, Supee Saksuwan Larsen)