Annual herb, erect, ascending or prostrate, 6-60 (-90) cm. Stem slender to stout, simple or considerably branched from the base or upwards, ± angular, green to reddish or yellow, quite glabrous or more rarely with 1-few-celled, short hairs above and/or in the inflorescence. Leaves glabrous or more rarely with scattered few-celled hairs near the base on the lower surface of the primary venation, long-petiolate (petiole frequently longer than the lamina), lamina ovate to rhomboid-ovate, 1-8 x 0.6-6 cm, shortly cuneate below, the apex usually broad and almost always conspicuously emarginate, mucronulate. Flowers green, in slender to stout terminal spikes and axillary cymose clusters (in small forms the terminal spike quite often indistinct) or rarely panicles, terminal spikes c. 0-6-11 cm long and 0.3-2 cm wide, the lower axillary inflorescences of dense cymose clusters up to 2 cm in diameter; male and female flowers intermixed. Bracts and bracteoles deltoid-ovate to lanceolate, whitish-membranous with a short yellow or reddish mucro formed by the excurrent midrib, bracteoles shorter than or rarely subequalling the perianth. Perianth segments 3 (occasionally 4 or even 5 in cultivated forms), membranous-margined, male and female both varying from lanceolate-oblong, subacute and mucronate to broadly spathulate and obtuse with the thick midrib ceasing below the summit, but the female often blunter, 0.75-2 mm. Stigmas 2-3, short, erect or flexuose. Capsule subrotund to shortly pyriform, compressed, exceeding the perianth, 1.25-2.5 mm, usually rather smooth but sometimes wrinkled on drying, indehiscent or rupturing irregularly at maturity. Seeds 1-1.75 mm, round, compressed, dark brown to black, the centre feebly reticulate and shining, the margin duller and minutely punctate-roughened over the reticulum.