Annual herb glabrous or with simple hairs, up to 15 cm tall. Leaves linear, up to 6 cm long undivided or divided into thin filiform segments. Flowers axillary, solitary or in pairs on sessile or short racemes. Sepals up to 5 mm long. Petal purple, about double the length of sepals. Siliquas rigid, curved, up to 22 x 3 mm ; the valves opening only on dorsal surface ; the fruits often crowded at base in addition to those borne higher up the plant.