An erect subglabrous or sparingly-pubescent annual up to 90 cm tall. Leaves mostly opposite, all petiolate, the petioles up to 4 cm long. Leaf-blades variable, elliptic-obovate to elliptic-oblanceolate or sometimes narrowly-lanceolate, 1-15 x 0.5-8 cm, the upper often narrower than the lower, acute, subacute or obtuse at the apex, cuneate or rounded-cuneate at the base, entire, denticulate or dentate, lateral nerves up to 20 pairs, subglabrous and dull green above, sparingly-puberulous and paler beneath, the upper leaves sometimes faintly purplish-blotched at the base. Stipules sessile, glandular. Inflorescence a pseudo-dichasium or rarely a triradiate pseudopleiochasium, with the cyathia aggregated together in dense terminal clusters. Glands 1-2 (-3), stipitate, circular, concave. Fruits roundly trilobate, 4-4.5 x 5-5.5 mm, smooth, glabrous. Styles connate at the base, 1 mm long, bifid. Seeds is quadrangular-ovoid, basally truncate, 2-2.5 x 1.5-2 mm, coarsely bluntly tuberculate, dark brown, ecarunculate.

Fl. & Fr. Per.: ± Throughout the year.

Holotyper Cultivated at Hampton Court, Middlesex, UK, from seed from Tropical America, in Hb. Morison (OXF).

Distribution: Throughout Tropical America from S. USA southwards; widely introduced into the Old World Tropics. In fields, farms and gardens; 1800'/550 m. -5000'/1525 in.