Annual herb to 50 cm high, glabrescent or sparsely pubescent with minute, simple hairs. Leaves alternate, 1 or 2 per node, narrowly elliptic, usually 5–7 cm long, c. 2 cm wide, apex acuminate, base cuneate, margins entire, sinuate or lobed; petiole to 4 cm long, grooved above. Flowers on pedicels 15–30 mm long; calyx 2.5–5 mm long, lobes triangular, 1–2.5 mm long. Corolla 5-angled, 5–7 mm long, yellow with darker yellow centre; anthers 1.5–2 mm long; style 2.5 mm long, stigma capitate. Fruiting calyx 10-angled, 25–32 mm long, pale yellow-green; berry globose, 12–15 mm diam.; seeds disc-shaped to broadly reniform, 1.5–2 mm long, pale yellow-brown. Flowers summer–autumn.
VRiv, GipP. Also naturalised WA, Qld, NSW. Native to Mexico and southern U.S.A. Recorded in Victoria at Mitiamo and Wodonga from seasonally wet sites with heavy clay soils.
