Phragmites japonicus Steud.

Perennial with underground rhizomes and long overground stolons; stolons bent zigzag, nodes hirsute. Culms up to 2 m tall, 4–5 mm in diam., nodes pubescent. Leaf sheaths tinged purple upward; leaf blades 10–30 × 2–3 cm, margins scabrous, apex acuminate; ligule 0.2–0.6 mm, ciliolate, hairs ca. 0.1 mm. Panicle 20–30 × 5–8 cm; axis puberulous; pedicels 6–7 mm, pilose, hairs soft, up to 2 mm. Spikelets purplish, 8–12 mm, florets 3–4; glumes acute, lower glume 1/2–3/5 length of lowest lemma, ca. 5 mm, upper glume ca. 5.5 mm; lowest lemma linear-lanceolate, 6–10 mm; floret callus bare in lower 1/3, upper 2/3 with silky hairs 3/4 length of lemma; bisexual lemmas very narrowly lanceolate, 6–9 mm, apex acuminate. 2n = 48.

Heilongjiang, Jilin, Liaoning [Japan, Korea, Russia (Far East, Kuril Islands)].

Swamps and lakesides; 200–1000 m.

Phragmites japonicus var. prostratus (Makino) L. Liu; P. prostratus Makino; P. serotinus Komarov.