Annual herb, erect, up to c. 1.5 m in height, commonly reddish or purplish throughout. Stem rather stout, not or sparingly branched, glabrous or thinly furnished with rather long, multicellular hairs which are increasingly numerous upwards. Leaves glabrous, or ± sparingly pilose along the margins and lower surface of the primary venation, long-petiolate (petiole to c. 8 cm but not longer than the lamina), lamina broadly ovate to rhomboid-ovate or ovate-elliptic, 2.5-15 x 1-8 cm, obtuse to subacute at the mucronulate tip, shortly cuneate to attenuate below. Flowers in axillary and terminal spikes formed of increasingly approximated cymose clusters, the terminal inflorescence varying from a single, elongate, tail-like, pendulous spike, to 30 cm or more long and c. 1.5 cm wide, to a panicle with the ultimate spike so formed; male and female flowers intermixed throughout the spikes. Bracts and bracteoles deltoid-ovate, pale-membranous, acuminate and with a long, pale or reddish, rigid, erect arista formed by the yellow-green or reddish stout, excurrent midrib, the longest up to twice as long as the perianth. Perianth segments 5; those of the male flowers oblong-elliptic, 2.5-3.5 mm, acute, aristate; those of the female flowers 1.75-2.5 mm, broadly obovate to spathulate, distinctly imbricate, abruptly narrowed to a blunt or sometimes faintly emarginate, mucronate tip. Stigmas 3, c. 0.75 mm, erect or flexuose. Capsule 2-2.5 mm, ovoid-globose, circumscissile, slightly urceolate, the lid smooth or furrowed below, abruptly narrowed to a short, thick neck. Seeds shining, compressed, black, almost smooth, or commonly subspherical with a thick yellowish margin and a translucent centre, c. 0.75-1.25 mm.