Perennial, 20-50 cm. Rhizome sturdy, ascending, scales grey or dark brown, disintegrating into fibres. Stem sharply trigonous, sides in upper part often concave, edges smooth or scabrous. Leaves equal to or overtopping stem; sheaths 20-50 mm, chestnut brown, disintegrating into fibres, margin of scarious side concave; ligule c. 0.3 mm, slightly arched; blades 3.5-4.5 mm wide, flat, keeled, margins slightly revolute, scabrous towards long-acuminate apex. Inflorescence of 1 male or gynecandrous spike and 3-6 female spikes below; bracts to much overtopping inflorescence, sheath-less; male glumes c. 3.9 x 2.4 mm, obovate or elliptic, dark reddish brown, apex rounded, mucronate and sometimes with a narrowly scarious margin; female spikes 10-32 x 4-5 mm, closely overlapping, cylindrical or ellipsoid, sessile or lowest remote with peduncle to 25 mm; female glumes 1.8-2.5 x 1.4-1.5 mm, elliptic, acute or with mucro up to 0.3 mm, dark reddish brown, papillose, occasionally scabrous; utricles 2.2-2.7 x 1-1.3 mm, ellipsoid to obovoid, obscurely nerved, yellowish green, papillose and occasionally scabrous, beak 0.2-0.3 mm, conical or cylindrical, truncate or shallowly bidentate, papillose, nerves scabrous. Stigmas 3. Nut 2.8 x 2 mm, incl. style base up to 0.3 mm, ellipsoid or obovoid, trigonous, yellowish brown, reticulate with papilla in each areole.