Diarrhena japonica Franch. & Sav.

Culms tufted, erect, 50–80 cm tall, 1–1.5 mm in diam., 4–5-noded, glabrous below nodes. Leaf sheaths mostly shorter than internodes, glabrous; leaf blades flat, 20–30 × 0.8–1.5 cm, glabrous or adaxial surface sparsely pilose, apex gradually acuminate; ligule 0.5–1 mm. Panicle open, ovate in outline, 10–20 × 8–20 cm; primary branches 1 or 2 per node, widely spreading, filiform, scabrid, sparingly branched, bearing up to 6 spikelets. Spikelets obovate at maturity, 3–5 mm, florets 1–3; glumes membranous, 1-veined, lower glume lanceolate, 0.8–1 mm, upper glume broadly lanceolate, ca. 1.5 mm, acute; lemmas lanceolate-ovate, lowest 2.7–3 mm, 3-veined, veins smooth, apex obtuse; palea keels smooth. Anthers 0.7–1.2 mm. Caryopsis 2.5–3 mm. Fl. and fr. Aug–Sep. 2n = 38.

Mountain slopes in forests. NE China [Korea (Cheju Island), Japan, Russia (Kunashir Island in S Kuril Islands)].

Neomolinia japonica (Franchet & Savatier) Probatova.