Annual, 60-150 cm tall, erect, branched. Leaves alternate, petiolate, triangular, broadly hastate at base, entire or more rarely toothed, mostly taper-tipped, green on both sides. Flowers in spikes disposed in a leafless panicle; staminate 5-merous; pistillate of 2 sorts, some ebracteolate with a 5-partite perianth and without bracteoles, others without perianth but with a pair of bracteoles, these rounded-oval, entire, free; seeds of the former type horizontal, convex, black, lustrous, 1-2 mm in diameter, those of the latter vertical, flat, olivaceous brown, dull, 3-4 mm in diameter.