Annual, 30-60 (-150) cm high, erect, usually branched. Leaves alternate, large, 5-10 cm long, long petiolate, truncate, cordate to hastate at base, sinuate-lobed or dentate to entire, lanceolate, tapering. Spicate inflorescences loose, simple or paniculate, leafless. Staminate flowers with 5-lobed, membranous perianth. Pistillate flowers of 2-forms: with 5-merous perianth and horizontal smaller seeds; others with 2 glabrous, membranous ovate or orbicular, reticulately veined, 5-15 mm long valves, with larger vertical seeds. Stigma free to base. Seeds 1-5 mm in diameter, brown or black.