Rhizome 2–3 mm. diam., short and woody, bearing distant, membr., apiculate, dark brown scales. Culms 20–60–(150) cm. × 1–2.5 mm., densely packed, rigid, erect, quadrangular, glab., blue- or grey-green. Lvs all reduced to brown, sheathing, membr., mucronate bracts, or the upper 1–2 with laminae quadrangular like the culm or occ. trigonous, 5–25–(35) cm. long, with a subulate, pungent, dark brown tip. Infl. 1–3–(4) cm. × 5–7–(15) mm., a dense, contracted, spike-like head; subtending bract us. < infl. with a rigid, subulate awn up to 1.5 cm. long. Spikelets 1-fld, 4–5 mm. long, on short, stout, stiff stalks. Glumes 4–6, the lowest broadly ovate, mucronate, the upper ones ovate-lanceolate, acuminate, coriac., papillose with scabrid midrib and margins, midrib thickened; only the uppermost glume fertile, the rest empty. Hypog. scales 6, c. 0.5 mm. long, white and triangular when mature, connate at the base to form a 6-lobed persistent cup. Anthers with an elongated red connective. Nut c. 4 mm. long, ± trigonous, oblong-ellipsoid, smooth, shining, light brown, narrowed above to the persistent, scabrid style-base.