Annual herb, erect, 0.4-2 m, simple or with many ascending branches. Stem and branches strongly ridged and often sulcate, quite glabrous. Leaves lanceolate-oblong to narrowly linear, acute to obtuse, shortly mucronate with the excurrent midrib, glabrous; lamina of the leaves from the centre of the main stem 2-15 x 0.1-3.2 cm, tapering below into an indistinctly demarcated, slender. petiole; upper and branch leaves smaller, markedly reducing; leaf axils often with small-leaved sterile shoots. Inflorescence a dense (rarely laxer below) many-flowered spike, 2.5-20 x 1.5-2.2 cm, silvery to pink, conical at first but becoming cylindrical in full flower, terminal on the stem and branches, on a long, sulcate peduncle up to c. 20 cm long, which often lengthens during flowering. Bracts and bracteoles lanceolate or towards the base of the spike deltoid, 3-5 mm, hyaline, ± aristate with the excurrent midrib, persistent after the fall of the flower. Perianth segments 6-10 mm, narrowly elliptic-oblong, acute to rather blunt, shortly mucronate with the excurrent midrib, with 2-4 lateral nerves ascending more than halfway up the centre of each segment, margins widely hyaline. Filaments very delicate, free part subequall¬ing or exceeding the staminal sheath, sinuses rounded with no or very minute intermediate teeth; anthers and filaments creamy to magenta. Stigmas 2-3, very short, the filiform style 5-7 mm long; ovary 4-8-ovulate. Capsule 3-4 mm, ovoid to almost globular. Seeds c. 1.25-1.5 mm, lenticular, black, shining, testa very finely reticulate.