Ischaemum barbatum Retz.

Perennial. Culms erect or ascending, 30–100 cm tall, often branched at base, nodes glabrous or bearded. Leaf sheaths glabrous to villous, margins ciliate or glabrous; leaf blades linear or narrowly lanceolate, 5–30 × 0.3–0.8 cm, glabrous to villous, margins scaberulous, base variable, cordate to attenuate or pseudopetiolate, apex acute; ligule 2–5 mm. Racemes terminal, paired, usually appressed back to back, 4–10 cm; rachis internodes oblong, triquetrous, ciliate along outer angle, inner angles glabrous or shortly ciliate. Sessile spikelet lanceolate-oblong, 5–7 × 1.6–2 mm; lower glume 2-keeled throughout, glabrous to villous, leathery, marginal nodules in lower 2/3, these sometimes extended into weak transverse ridges, herbaceous above with many anastomosing green veins, keels asymmetrically winged, one wing wider than the other; awn of upper lemma 1–1.5 cm. Pedicelled spikelet dorsally compressed, as large as sessile but marginal nodules less developed, awnless or awned.

Swamps.