Prostrate or straggling annual or perennial herb up to c. 1 m high. Stems sometimes woody near the base, more or less densely covered in rough hairs, sparsely armed with short, prickles. Leaves sensitive, twice compound with (1-)2 pairs of pinnae; rhachis very short, making the leaf appearing palmately divided. Flowers in ovoid-globose heads, c. 1.3 × 1 cm, in the upper leaf axils, lilac or pink. Pods in clusters, 1-2 cm long, densely prickly or bristly on the margins only.