Prostrate or ascending annual herb; stems to c. 60 cm long, glabrous or sparsely hairy; hairs simple. Leaflets obovate to obcordate, 5–30 mm long, 3–22 mm wide, minutely dentate especially towards apex, both surfaces more or less glabrous, upper surface sometimes with darker flecks, apex truncate or emarginate with a terminal tooth; stipules to c. 15 mm long, laciniate, glabrous or lower surface hairy. Inflorescence 2–10-flowered; peduncle 0.5–2 cm long, shorter or longer than subtending petiole. Flowers sub-sessile; calyx 2–5 mm long, teeth equal, as long as or longer than tube; corolla yellow; standard 3–5 mm long; wings longer than keel. Pod with 2–7 loose, thin coils, discoid or cylindric, 2–12 mm long, 3–10 mm diam., glabrous, spiny or tuberculate; coil edge thin; face with 15–20 strongly curved anastomosing veins; marginal vein raised above level of submarginal veins; groove deep; spines to 18 on each side of coil, 0–4 mm long; seeds 3–11, 2–4 mm long, yellow-brown. Flowers mainly Aug.–Nov.
LoM, MuM, Wim, GleP, Brid, VVP, VRiv, MSB, RobP, MuF, GipP, OtP, WaP, Gold, CVU, GGr, DunT, NIS, EGL, EGU, WPro, HSF, HNF, OtR, Strz, MonT, VAlp. Naturalized all States, New Zealand and most other parts of the world. Native to the Mediterranean region. Distributed widely throughout most of Victoria where found mainly in pastures, disturbed ground and along road verges.
3 varieties are commonly recognized (e.g. Heyn 1963, Wiersema et al. 1990) based mainly on the pod size, decoration and number of coils. According to Lesins & Lesins (1979) these varieties are somewhat artificial, and the Australian material has pods with a wide variety of spine lengths occurring in various combinations with the other pod characters.
In addition to the characters given in the key, this species can be distinguished from M. laciniata by the curved anastomosing radial veins on the coil surface and thin partitions between the seeds. In M. laciniata the veins are sigmoidal and hardly anastomosing and there are no seed partitions.
