Culms trigonous, angles obtuse, 4–35 cm, scabrous distally. Leaves basal; sheath fronts with apex concave to V-shaped, glabrous; blades 7–25 cm × 1.5–3 mm, shorter than culm. Inflorescences 2–4 cm; proximal bracts to 5 × 1 mm; spikes crowded; lateral spikes 0.5–1.5 cm × 4–5 mm; terminal spikes 1–2 cm × 4 mm. Scales brown with yellow-brown midrib, 3-veined, equaling perigynia, apex acuminate to retuse, with scabrous awn to 2 mm. Anthers 2–3 mm. Perigynia yellow-brown, often red-brown at apex, sides convex, 2.5–2.8 × 1.5 mm, hairs purple-brown (hair-base bulbous); beak red-brown, conic, thickened. Achenes brown, sessile, mitrate, obovoid, 2–2.2 mm. 2n = 58, 62, 64, 66, 68 (Europe, Japan).
