Annual herb, branched from the base and usually also above, erect, decumbent or prostrate, mostly up to c. 45 cm. (rarely to 70 cm.). Stem slender to stout, angular, glabrous or thinly to moderately furnished with short to long, often crisped multicellular hairs which increase upwards, especially in the inflorescence, leaves glabrous or sometimes sparingly furnished on the lower surface of the principal veins with very short, gland-like hairs, long-petiolate (petiole from 3-4.5 mm, sometimes longer than the lamina), lamina broadly ovate or rhomboid-ovate to narrowly linear-lanceolate or linear, 4-55 x 2-30 mm, acute to obtuse or slightly retuse at the mucronulate tip, cuneate to long-attenuate at the base. Flowers all in axillary cymose clusters, male and female intermixed, males commonest in the upper whorls. Bracts and bracteoles narrowly lanceolate-oblong, pale-membranous, acuminate and with a pale or reddish arista formed by the excurrent green midrib, bracteoles subequalling or usually shorter than the perianth. Perianth segments 3, all 1.5-2 mm; those of the male flowers lanceolate-oblong, acute or subacute, pale-membranous with a narrow green midrib excurrent in a short, pale arista; those of the female flowers lanceolate-oblong to linear-oblong, gradually to abruptly narrowed to a very short to rather long mucro, the midrib often bordered by a green vitta above and apparently thickened, the margins pale whitish to greenish. Stigmas 3, slender, usually pale, flexuose, c. 0.5 mm. Capsule subglobose to shortly ovoid, 2-2.25 mm, usually strongly wrinkled throughout with a very short, smooth neck, slightly exceeding the perianth, circumscissile or sometimes not, even on the same plant. Seeds shining, compressed, black, 1-1.25 mm, faintly reticulate.
Type: Linnean specimen 117/3 (LINN, holotype!).