3. Leersia oryzoides (Linnaeus) Swartz, Prodr. 21. 1788.
蓉草 rong cao
Phalaris oryzoides Linnaeus, Sp. Pl. 1: 55. 1753; Asprella oryzoides (Linnaeus) Lamarck; Homalocenchrus oryzoides (Linnaeus) Haller; Oryza oryzoides (Linnaeus) Brand & W. D. J. Koch.
Perennial, loosely tufted, with slender rhizomes. Culms weak, decumbent, rooting at lower nodes, upper part up to 120 cm tall, branching near base, scabrid below panicle, nodes retrorsely hispid. Leaf sheaths longer to slightly shorter than internodes, the upper retrorsely spinulose; leaf blades thin, 7–30 × 0.6–1 cm, scabrid on both surfaces, margins scabrid and spinulose, apex acuminate; ligule 1–2 mm, truncate. Panicle lax, ovate in outline, 10–20 cm; branches 1–3 per node, spreading, up to 10 cm, flexuous, very slender, scabrid, lower part long naked, upper part with branchlets bearing spikelets overlapping along one side of branchlets. Spikelets elliptic-oblong, 5–6 mm, whitish with green veins; lemma conspicuously pectinate-hispid on keel and margins, surface strigillose, sometimes sparsely, apex abruptly contracted, subacute. Stamens 3, anthers 1.5–2 mm. Fl. and fr. Jun–Sep. 2n = 48, 60.
Wet river banks, marshy places; 400–1100 m. Fujian, Hainan, Heilongjiang, Hunan, Xinjiang [Kazakhstan, Kyrgyzstan, Russia, Tajikistan, Turkmenistan, Uzbekistan; N Africa, SW Asia (Caucasus), Europe, North America; introduced in Australia].
This widespread species has a more temperate distribution than Leersia hexandra. The panicles are sometimes produced only within inflated upper leaf sheaths, which remain included and bear cleistogamous spikelets with much smaller, 0.5 mm anthers. These enclosed panicles are produced under cooler conditions.