Perennials, (20–) 30–80 cm tall. Rhizome horizontal, creeping, long, branched, with internodes up 1.5 cm long, pale brownish; sterile shoots sometimes present. Stem erect, 1.5–4 mm in diam.; cataphylls 1–2, lax, later disappearing. Cauline leaves 2–4, usually 6–15 cm long, 1.0–1.5 mm in diam., unitubular, perfectly and prominently septate; auricles scarious to pale brownish, subacute to obtuse, c. 2.0–3.5 mm long. Stems, sheaths and leaves strongly longitudinally striate to sulcate (in transverse section with protuberances formed by epidermal cells irregularly superposed). Lower bract leaf-like, usually to 2 cm, much shorter than inflorescence. Inflorescence lax, anthelate, compound to decompound, of (2–) 7–20 (–50) semiglobose to globose dark brown (5–) 8–30 (–35)-flowered heads. Tepals unequal; inner tepals 2.8–3.8 mm long, narrowly lanceolate to lanceolate, gradually acuminate, cuspidate; outer 2.5–3.5 mm long, acute or mucronate, slightly deflexed at apex, greenish to stramineous-brown proximally, dark castaneous-brown apically; midrib very prominent; margins very narrow, scarious. Stamens 6; anthers 0.9–1.4 mm long, 1.5–2 (–3) times as long as c. 0.5 mm filaments; style to c. 0.3 mm long; stigmas 1.0–1.5 mm long. Capsule 3.5–4.5 mm long, exceeding perianth, unilocular, acutely trigonous, narrowly oblong-ovoid, tapering to a 0.7 mm rostrum, brownish, shiny. Seeds narrowly ovoid, (0.4–) 0.45–0.55 × c. 0.2–0.3 mm, pale brown, reticulate; appendages absent.