Herbs or shrubs; stems armed with prickles. Leaves 2-pinnate, sensitive (in ours). Inflorescences of ovoid or subspherical heads which are axillary or arranged in clusters. Flowers bisexual or male. Calyx very small. Corolla gamopetalous, (3-)4(-6)-lobed. Pods flat, bristly or prickly (in ours), splitting transversely into 1-seeded segments.