高山眼子菜 gao shan yan zi cai

Potamogeton rufescens Schrader; P. tenuifolius Rafinesque.

Plants perennial, in fresh water, usually with reddish tinge particularly when dry. Rhizome slender. Stems terete, 1.5-2 mm in diam., simple, but sometimes with horizontal stolons. Leaves dimorphic; stipules axillary, convolute, herbaceous, slightly amplexicaul, 12-35 mm. Submerged leaves sessile, lanceolate to linear-lanceolate or elliptic-oblong, 5-38 × 0.7-3.3 cm, 9-19-veined, with broad rows of lacunae bordering midvein, base cuneate, margin entire, apex obtuse. Floating leaves petiolate; blade elliptic to broadly lanceolate, 4-9 cm × 8-25 mm, leathery or subleathery, (5-)7-13-veined, base cuneate to narrowly cuneate, margin entire, apex obtuse. Spikes cylindric, 6-15 cm, densely flowered; peduncles thicker than stem. Carpels 4. Fruit obovoid, 2.6-3.7 mm, abaxial keel somewhat sharp, with a short beak. Fl. and fr. Jul-Sep. 2n = 52.

Lakes, ponds, marshes, usually in slightly alkaline water. Heilongjiang [Afghanistan, India (Assam), Japan, Kazakhstan, Korea, Myanmar, Pakistan, Russia, Uzbekistan; Europe, North America].