Annual or perennial herbs sometimes with a woody base. Leaves opposite, paripinnate, one of each pair usually larger than the other. Leaflets opposite, entire, slightly asymmetrical. Flowers solitary, axillary. Petals yellow. Ovary 5-lobed, densely stiffly hairy. Fruit
breaking up into 5 cocci, each coccus tuberculate on the back, spiny, 1-5-seeded.
Worldwide: 25 species in tropical and warm areas, especially dry parts of Africa