Asian Watergrass

A floating grass forming pure mats on the surface of the water; cattle are fond of it and people have been known to eat the grain.

Floating aquatic herb; culm soft, rooting at nodes; ligules hyaline, apex truncate, 0.8 mm long; leaf-blades ovate to lance-ovate, 2-7 cm long, 1-2 cm wide, upper surface pappilate. Panicle loose, globose; axis short, 4-9 branches. Spikelets 1.8-2 cm long, including long awn; glumes none; lemma 5-nerved, lance-elliptic, suddely narrowed at both ends, hispidulous; callus stipe-like; palea as long as lemma, 3-nerved.

Culms floating, 0.5–1.5 m long. Leaf blades 3–7 × 0.5–2.5 cm, adaxial surface papillate, base rounded to cordate, abruptly constricted to a ca. 1 mm petiole-like base at junction with sheath, apex obtuse; ligule truncate, 0.5–0.8 mm. Inflorescence triangular in outline; branches short, lowermost subverticillate, reflexing at maturity. Spikelets greenish; stipe 3–6 mm; lemma body 7.5–8 mm, hispidulous on back, spinulose on veins; awn 1–1.4 cm; palea keeled and spinulose along midvein, outer veins smooth, apex acute. Anthers ca. 3.5 mm.

Mat-forming perennial; stems 30 cm or more long, spongy, with whorled feathery roots at the nodes. Leaf-blades flat, ovate-oblong, obtuse, 2.5-7.5 cm long, 12-20 mm wide, scaberulous above, smooth and glaucous beneath, rounded or subcordate at the base. Panicle triangular, 3-6 cm long and wide, the lower branches spreading or sometimes deflexed. Spikelets sessile or very shortly pedicelled with a long pedicel-like callus articulated with the panicle-branch or pedicel and falling with the spikelet; body of lemma up to 10 mm long, passing into the 10-12 mm long, scaberulous awn.

Nepal, India, Ceylon, Burma, S.E. Asia, China, Malaysia.

Tropical Asia, India, Ceylon, Indo-China, southern China, and Taiwan to Malesia.

Distribution: as for genus.

200 m

An aquatic grass forming extensive floating mats in ponds and lakes, often in shade of trees. Fujian, Guangdong, Hainan, Taiwan, Yunnan [Bangladesh, Cambodia, India, Laos, Malaysia, Myanmar, Nepal, Pakistan, Sri Lanka, Thailand, Vietnam].

Pharus aristatus Retzius, Observ. Bot. 5: 23. 1789; Pota-mochloa aristata (Retzius) Griffith ex Steudel; Zizania aristata (Retzius) Kunth.