Herb, dioecious, rhizomatous, perennial, forming patches of culms to 1 m across. Rhizomes horizontal, 2–3 mm diam.; scales brown, scarious, partly covering pale brown woolly pubescence. Culms sometimes dimorphic, fertile culms crowded or to 1 cm apart, erect, straight, terete, unbranched, 40–75 cm long, 0.8–1.5 mm diam., green, striate, glabrous; internodes 4–8, 5–12 cm long; vegetative culms short and sinuous. Sheaths imbricate, appressed at the base, distally lax and open, narrow-obovate, 1.0–1.8 cm long, striate, pale brown or reddish; apex obtuse to truncate, with a narrow, membranous margin; lamina slender, erect, 1–2 mm long. Inflorescence slender, erect, (3–) 5–17 cm long; spathes similar to sheaths but shorter. Male spikelets mostly on short erect branches, ovoid, 4–6 (–8.5) mm long, 1.5–3 mm wide. Female spikelets singly or few at many upper nodes, narrow-obovoid, c. 6 mm long, 2.5 mm wide. Male glumes: 1 or 2 sterile lower glumes and 4–20 fertile upper glumes, dark brown, glabrous, acute, 2–4 mm long. Female glumes: lower 1–3 sterile, upper 1 or 2 fertile; narrow-elliptic, dark brown, glabrous, 4–4.5 mm long, with a dark mucro to 0.5 mm long. Male flowers: tepals 5, linear-lanceolate, brown-hyaline, glabrous; outer tepals keeled, 2.5–2.8 mm long; inner tepals flat, 2.2–2.4 mm long; stamens 3; anthers 1.2–2 mm long. Female flowers: tepals 5, similar to males, 3.5–4 mm long; outer tepals lanceolate, pubescent along keel; inner tepals broad lanceolate, glabrous; ovary 2-locular, sometimes only 1 locule developing; styles 2, connate and persistent at the base. Capsule almost circular in outline 3–3.5 mm long, smooth, brown. Seed ovoid, 1.5–1.9 mm long; colliculate with lines of convex cells. Culm anatomy: chlorenchyma interrupted by pillar cells.
Home