5. Glyceria leptorhiza (Maximowicz) Komarov, Trudy Imp. S.-Peterburgsk. Bot. Sada. 20: 307. 1901.
细根茎甜茅 xi gen jing tian mao
Glyceria fluitans (Linnaeus) R. Brown var. leptorhiza Maximowicz, Prim. Fl. Amur. 320. 1859.
Perennial, rhizomatous; rhizomes filiform. Culms ascending, 20–50 cm tall, 1–2 mm in diam. Leaf sheaths smooth, upper shorter than internodes; leaf blades flat, thin, 7–10 cm × 1.5–3.5 mm, smooth; ligule 1–3 mm. Panicle narrow, contracted, 6–25 cm, base included in uppermost leaf sheath; branches 1–3 per node, erect, appressed to main axis, smooth, bearing 1–4 spikelets. Spikelets linear, 8–14 mm, florets 5–9, pale green or pinkish; glumes ovate-oblong, 1-veined, lower glume 2–3 mm, upper glume 3–4 mm, apex obtuse; lemmas oblong, 3–4 mm, smooth, 7-veined, upper margins and apex narrowly membranous, apex obtuse; palea slightly longer than lemma, keels wingless, apex emarginate. Stamens 3, anthers 1–1.7 mm. Fl. and fr. Jul–Aug. 2n = 20.
River banks, shallow water, swampy grasslands. N Heilongjiang [Russia (Far East, E Siberia)].
Reports of this species in Japan refer to Glyceria depauperata Ohwi (G. leptorhiza subsp. depauperata (Ohwi) T. Koyama), which differs from G. leptorhiza in having spikelets to 25 mm, florets 7–15, and anthers 0.5–0.7 mm.