Japan Flora: Nearly glabrous annual, with procumbent stems; stipules laciniate, the leaflets broadly obovate, 1-2 cm. long, 7-15 mm. wide, retuse to rounded, cuneate at base, denticulate on upper half; heads rather few-flowered, axillary, the bracts minute, linear; calyx about 2 mm. long, the teeth subulate, incurved; legumes 2- to 3-times spirally coiled, 5-6 mm. across, nerved, with hooked spines on margins.
Widely naturalized in our area. Europe and n. Africa.