Robust tufts, 0.6-1.2- (2) m high. Stems sharply 3-angled with very sharply scabrid leaves. Leaves and sheaths with evident minute transverse septa between veins. Involucral bracts many, much > inflorescence. Inflorescence usually a simple umbel; rays 6-12, unequal. Spikelets crowded at end of each ray into dense spikes ± 5 cm long. Glumes hard, shining, usually purple-brown.

Robust, 60–120–(200) cm. tall, with lvs crowded at base of culms. Culms triquetrous, glab., striated. Lvs 60–120 × 0.8–1.5 cm., lamina coriac., strongly keeled, multitubular with ∞ septa prominent on the abaxial side, margins and keel very sharply and minutely serrulate; sheath brown. Infl. a terminal umbel 4–14 cm. long, of 6–12 unequal rays; rays us. unbranched, rarely with secondary branches at base; involucre of ∞ lf-like bracts very much > infl. Spikelets 8–13 mm. long, ∞, dark brown or yellow-brown, crowded on each ray into a dense spike (2.5)–3–5–(7) cm. long. Glumes 5–20 in each spikelet, ovate-oblong, obtuse or mucronate, hard, smooth and shining, keeled, red-brown with white nerves, 2 or occ. 3 lowermost and 1–2 uppermost glumes smaller, empty, the remainder fertile. Stamens with persistent filaments. Nut 1.5–2 × c. 0.5 mm., c. ½ length of glume, linear-oblong, trigonous, brown.