Herbs, dioecious, perennial; mostly forming extensive diffuse patches. Rhizome elongated, horizontal, usually straight but sometimes arcuate, 2–5 mm diam., with a pale woolly pubescence; cluster and sand-binding roots present. Scales pale brown to dark red-brown, often partially pubescent. Culms closely or widely spaced on the rhizome, erect, straight to sinuose or convoluted, terete, 0.5–1.5 mm diam., 10–80 cm long, green to grey-green, glabrous to pubescent, smooth to minutely tuberculate. Sheaths caducous, oblong to broad-oblong, dark brown at the base and paler towards the apex, 1–2 cm long, apex obtuse with an erect, terete lamina 1–2 mm long. Spikelets solitary and terminal on the culm, or occasionally 1 or 2 also sessile or on short branches from the uppermost nodes; spathes similar to sheaths but shorter and usually persistent. Male spikelets ovoid, 10–20 mm long, 8–15 mm wide. Male glumes numerous, a few lower glumes sterile and the upper glumes fertile, broad-oblong, 3.5–5 mm long; apex obtuse to truncate, shortly ciliate; awn erect, rigid, awn 1–2 mm long. Female spikelets ellipsoid to obovoid, 8–18 mm long. Female glumes 8–15, a few lower glumes sterile, upper glumes fertile, oblanceolate, c. 4–7 mm long, pale brown; apex shortly ciliate; awn rigid, erect, black, 3–5 mm long. Male flowers: tepals glabrous; outer tepals narrow, acute or mucronate, 3–5 mm long; inner tepals oblanceolate, 3.5–5.5 mm long; filaments 6–8 mm long; anthers 2–3 mm long. Female flowers: tepals 5, hyaline, glabrous; outer tepals rigid, acute to shortly mucronate, 4–4.5 mm long; inner tepals membranous, 2.5–3.5 mm long. Nut 2.5–3 mm long, black, ± globose with a short stipe and the style base forming a conical cap. Seed ± globoid, brown, 1.5–2 mm long. Culm anatomy: with a central cavity; chlorenchyma continuous, mostly of a single layer of elongated peg cells; mostly with inward-projecting epidermal cells partially lining substomatal cavities; walls of epidermal cells thickened on outer wall and outer part of radial walls; radial walls often sinuous; often with radially elongated epidermal cells forming mounds on the culm surface; with stalked, branched multicellular hairs.
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