Homalocenchrus oryzoides (Linnaeus) Haller var. japoni-cus (Hackel) Honda; Leersia hackelii Keng; L. oryzoides (Linnaeus) Swartz var. japonica Hackel; L. oryzoides subsp. japoni-ca (Hackel) T. Koyama.

Perennial, tufted, with rhizomes. Culms ascending, 30–70 cm tall, nodes retrorsely hispid. Leaf sheaths retrorsely spinulose; ligule 1–2 mm, truncate; leaf blades grayish green, 7–10(–20) × 0.5–1 cm, margins scabrid; ligule ca. 0.5 mm, truncate. Panicle lax, ovate in outline, up to 20 cm, base often enclosed in terminal leaf sheath; branches inserted singly, spreading, up to 10 cm, slenderly triquetrous, scabrid, branched or not, lower part long naked. Spikelets narrowly oblong, 6–8 mm, pale green, whitish along keel; lemma hispid on keel, surface sparsely hispidulous, apex abruptly contracted, obtuse. Stamens 3(or 2), anthers 1–2 mm. Fl. and fr. autumn.

This species is very close to Leersia oryzoides and is not completely distinct from it. It can usually be recognized by its longer, less conspicuously hispid spikelets. Leersia sayanuka is not known to produce panicles with cleistogamous spikelets in the leaf axils.

Forests, streamsides, lake shores, moist grassy places. Anhui, Fujian, Guangdong, Guangxi, Guizhou, Hubei, Jiangsu, Shandong, Zhejiang [Japan, Korea].