Rhizomatous perennial. Culms 15–100 cm high, 1–2 mm diam., spread along relatively stout, tough rhizome. Leaves reduced to orange-brown sheaths. Inflorescence a dense globose or hemispherical head 7–20 mm diam., with numerous spikelets; involucral bract rigid, pungent, exceeding inflorescence; glumes obtuse, sides irregularly several-nerved, red-brown, 2–2.5 mm long; stamens 3; anthers c. 1 mm long; style 3-fid. Nut plano-convex to unequally trigonous, irregularly ellipsoid, smooth, glossy, dark brown to black, about half as long as glume, c. 1 mm long, c. 0.7 mm diam., with small basal hyaline or white lobed disk deciduous or persistent. Flowers spring.