Tufted perennial, 60-90 cm. Rhizome horizontal or ascending, black-brown, short internodes covered by soon fibrous scales and remains of old shoots. Stems noded, trigonous, smooth. Leaves from half to c. 2/3 of stem length; sheaths 25-70 mm, grey or reddish brown, finally fibrous and almost black, margin slightly concave; ligule short, brown, arch lower than wide; blades 2-4 mm wide, keeled, flat or carinate, grey-green, scabrous along margins. Inflorescence of 4-8 partial inflorescences in leaf axils; bracts green, lowest longer than its partial inflorescence; partial inflorescences branched or unbranched, of 1-5 spikes, lower often large, peduncles to 12 cm; spikes up to 35 mm, lax, pedunculate, erect or nodding. Utricles c. 3 mm, ellipsoid, conspicuously nerved, margins and nerves barbed, stipe short, beak c. 1 mm, ostiole oblique. Stigmas 2.