Herb, dioecious, perennial, forming large diffuse patches. Cluster-roots present. Rhizomes stout, horizontal or arcuate, 5–6 mm diam., with a ± continuous covering of brown scarious scales covering a pale woolly pubescence or glabrous. Cataphylls several, 5–25 cm long, appressed, brown, papery, covering the base of a greatly elongated sheath extending up the culm as much as 25 cm and sometimes with a second elongated sheath just above the first up to 15 cm long, dull brown, obtuse with an erect lamina c. 5 mm long. Culms spaced on the rhizome at intervals of c. 1–4 cm, terete, 1.0–1.5 m long, 2–7 mm diam. at the base, 1–2 mm diam. mid-culm, yellow-to blue-green, smooth to subrugose, simple or infrequently branched. Sheaths: cauline sheaths 1.5–3.0 cm long, dull-to dark-brown; lamina erect or occasionally reflexed, c. 5 mm long. Inflorescence usually interrupted, 3–10 cm long, with short ascending branches to 2 cm long densely crowded with flowers; spathes on the main axis ± sheath-like although shorter and narrower and becoming acute and scarious towards the inflorescence apex; bracts numerous on the branches and to 5 mm long, lanceolate, hyaline, acuminate to aristate with a filiform awn, pale-brown. Male flowers sessile or shortly pedicellate: tepals scarious, yellow-brown, lanceolate, cuspidate to aristate with a short erect awn, c. equal in length or the outer slightly longer, 2.5–4.0 mm long; filaments c. 1.5–2.5 mm long; anthers exserted, c. 1 mm long; pistillode minute. Female flowers sessile or shortly pedicellate. Capsule globose, 1.5–1.8 mm diam. Seed ovoid, colliculate; colliculi small, circular. Culm anatomy: epidermal cells with sinuous walls and globular silica bodies, transverse (horizontal) lines of stomates visible on culm surface, chlorenchyma of horizontal plates of palisade-like cells (2 layers of short cells), pillar cells absent, substomatal cavities lined by protective cells, central cavity angular, (2-or) 3-angled.
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