Southern Cutgrass

Wet place.

This is a serious weed of rice fields in tropical regions.

Loosely tufted perennial; culm base decumbent, rooting at nodes; swollen nodes retrorsely puberulent; ligules membranous, 1-2 mm long; leaf-blades narrowly linear-lanceolate, 3-15 cm long, 2-6 mm wide, scabrous. Panicle loose, narrowly elliptic. Spikelets 3-5 mm long, 1.2-1.5 mm wide, contracted at base; lemma 5-nerved, boat-shaped, hispidulous, bristly-hispid on keel; palea same texture and length as lemma, 3-nerved.

Perennial with well-developed stolons and slender rhizomes. Culms decumbent, rooting at lower nodes, erect shoots up to 50 cm or more tall, nodes retrorsely pubescent. Leaf sheaths shorter than internodes, smooth or scabrid; leaf blades flat or sometimes rolled, 5–12 × 0.3–0.6 cm, abaxial surface scabrid on midrib, base contracted, apex sharply acute; ligule 1–3 mm, truncate. Panicle lanceolate-oblong in outline, 5–10 cm, exserted; branches inserted singly, ascending, 4–5 cm, unbranched, slenderly terete or triquetrous, densely clothed to near base with closely overlapping spikelets. Spikelets narrowly elliptic to elliptic-oblong, 3–4 mm, pale green or purple tinged; lemma conspicuously pectinate-hispid on keel, lateral veins and sometimes surface sparsely spinulose, margins shortly hispid, apex contracted into a short obtuse beak. Stamens 6, anthers 2–2.5 mm. Fl. and fr. May–Dec. 2n = 24, 48.

Tropics of Old & New Worlds.

Pantropics; suthern Ryukyus, Taiwan, and Hainan in eastern Asia.

200-300 m

Slow-moving shallow water of lake margins, ditches, and depressions, marshlands, sometimes forming floating mats. Fujian, Guangdong, Guangxi, Guizhou, Hainan, Sichuan, Taiwan, Yunnan [Bangladesh, Bhutan, India, Indonesia, Japan (Ryukyu Islands), Malaysia, Myanmar, Nepal, New Guinea, Philippines, Sri Lanka, Thailand, Vietnam; Africa, America, Australia].

Leersia australis R. Brown; L. parviflora Desvaux.