(Thunb.) Mast., J. Linn. Soc., Bot. 14: 419 (1875)
Vegetative parts: plants clumped, 1–1.5 m tall, basal diameter 1–2 m, crown diameter 1–2 m, with rhizomes. Rhizome very short with culms aggregated at base, 4–7 mm in diam., culms 3–6 mm apart. Fertile culms unbranched, smooth (drying somewhat rugose), olivaceous, 0.8–1.5 m tall, diameter at base 1.4–3 mm, diameter at apex 0.7–1.7 mm. Sheaths closely convoluted, 30–50 mm long, greenish-yellow darker towards margins, apical margins broadly chartaceous and soon decaying (but only a relatively narrow upper portion), hyaline shoulders absent, apex, excluding the membranous lobes, acute. Sheath-mucro absent. Sterile branch leaf-sheath 2–3 mm long, hyaline shoulder 2–3 mm long, lacerated, leaf-blade 5–6 mm long; leaf blade 0.2–0.3 mm wide. Males: male inflorescence with 21–50 spikelets or 50–100 spikelets or 101–500 spikelets, paniculate, 50–250 mm long, 25–50 mm wide. Male inflorescence spathes persistent, upper margins lacerated and largely decayed at anthesis, shorter than spikelets, chartaceous. Male flowers in spikelets. Male spikelets pendulous on flexible pedicels, oblong or ovate, apex rounded, 5–12 mm, 2.5–5 mm, with 12–24 flowers, pedicels shorter than the spikelets or as long as the spikelets or longer than the spikelets, flattened. Male bracts shorter than flowers or as tall as flowers, 2–4 mm long, oblong or ovate, acute, chartaceous, bract upper margin like body of bract, bract awn minute or absent, with very narrow membranous margins. Male flower 2–3.5 mm long. Male tepals sepals more rigid than petals, chartaceous, petals chartaceous, oblong, inner and outer tepals the same length. Male outer lateral tepals conduplicate, glabrous. Anthers 1.5–1.8 mm long, included in the flowers. Pistillode absent. Females: female inflorescence linear or paniculate, 40–300 mm long, 10–40 mm wide, with 6–10 spikelets or 11–20 spikelets or 21–50 spikelets. Female spathes longer than the spikelets, not obscuring spikelet, persistent, chartaceous. Female spikelet pedicel simple or pedicel sparsely branching or pedicel much branched, elliptical or ovate or obovate, apex rounded or obtuse, 8–20 mm long, with 1–16 flowers, with 0 sterile bracts. Female bracts taller than flowers, 6–10 mm long, oblong or ovate, acute, chartaceous or cartilaginous, apical margin like rest of bract, same as body of bract, awn minute or absent. Female flower 3–4 mm long, without a fleshy pedicel. Female tepals cartilaginous, glabrous and smooth, at least as tall as nut, wrapped around it and obscuring the surface, midrib flush with the tepal body, apices acute, inner and outer whorls the same length. Female outer lateral tepals keeled or winged, wings entire, wider than body, hidden by bracts, or bracts are shorter than flowers or exserted past bracts, 3–4 mm long. Female odd outer tepal oblong, 2.5–3.3 mm long. Female inner tepals oblong, 2.5–3 mm long. Staminodes absent. Styles plumose, white, 1. Ovary with 1 locule, indehiscent. Fruit: indehiscent fruits with a softer ovary wall. Perianth presence on fruits persistent, winged. Shape of winged dispersal unit orbicular. Nut apex smooth, without a distinct cap, wall smooth, (1.64–)1.94(–2.4) mm long, 1.2–1.8 mm diam., shape in side view obovate, shape in top view elliptical in cross section, brown. Elaiosome absent.