Schmidtia subtilis Trattinnick, Fl. ╓sterr. Kaiserth. 1: 12. 1816; Wilibalda subtilis (Trattinnick) Roth; Zizania subtilis (Trattinnick) Raspail.

Culms spreading, forming small mat, branching at lower nodes, ascending up to 5(–10) cm. Leaf sheaths inflated; leaf blades ca. 1 cm × 1–4 mm, smooth, glabrous; ligule 0.5–3 mm. Panicle 0.5–3 cm; pedicels verticillate, 1–2 mm, setulose. Spikelets lanceolate; lemma 0.8–1.3 mm, vein scabrid; awn ca. 1 mm; palea 0.5–1 mm, keels scabrid or almost smooth. Anthers 0.3–0.4 mm. Caryopsis 1.7–2.1 mm, dark brown. Fl. and fr. spring to summer. 2n = 14.

Muddy streamsides, lake margins, other wet places, forming colonies. NE China, Jiangxi [Russia; Europe; probably introduced in North America (NW United States)].