Tufted perennial, 10-60 cm. Rhizome with short stolons. Stem sharply trigonous, edges very scabrous, grey-green, papillose. Leaves c. 1/2 of stem length; sheaths 15-40 mm, from yellowish brown to dark brown, finally fibrous, margin of scarious side concave; ligule c. 0.3 mm, arch twice as high as wide; blades (2-)3-5(-7) mm wide, flat, margins recurved, margins and main nerves on upper side scabrous. Inflorescence of 1(-2) male and 2-4 female spikes, usually overlapping, upper sometimes androgynous, lower occasionally short-pedunculate and drooping. Bracts to as long as their spike, sheath-less, with stipule-like basal brown to black appendages. Male spike 15-30 mm, narrowly ellipsoid or club-shaped; male glumes 3.2-4.7 x 0.8-1 mm, spathulate, apex rounded, brown to dark brown. Female spikes 10-25 x 3-5 mm, ellipsoid or cylindrical; female glumes (1.6-)2-3 x 0.6-1.1 mm, triangular, mid-nerve not reaching rounded apex, mostly from dark to black-brown; utricles 2-2.8 x 1.6-2.3 mm, almost globular or ellipsoid, bi-convex or plano-convex, slightly inflated, nerveless to faintly nerved, green to almost black, glossy, papillose, smooth, beak 0-0.2 mm, ostiole round, margins papillose or ciliate. Nut 1.7-2 x 1.2-1.5 mm, incl. style base up to 0.3 mm, ellipsoid to obovoid, bi-convex, brown, finely reticulate.