Description from Flora of China
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)