4. Potamogeton mandschuriensis (A. Bennett) A. Bennett, Trans. & Proc. Bot. Soc. Edinburgh. 29: 50. 1924.
东北眼子菜 dong bei yan zi cai
Potamogeton acutifolius Link ex Roemer & Schultes subsp. mandschuriensis A. Bennett, J. Bot. 42: 76. 1904.
Plants submerged in fresh water. Rhizome slightly compressed, 0.9-1.5 mm wide. Stems slightly compressed, sparsely to densely branched; turions axillary or terminal, shortened shootlike, leafy. Stipules axillary, convolute, 1.5-2 cm, herbaceous and translucent, often fibrous-persistent; leaves sessile, linear, 3-12 cm × 1.5-2.3 mm, 3-veined with 8-14 faint sclerenchymatous fibers, with narrow rows of lacunae bordering midvein, base narrowly cuneate, apex finely acuminate or acute. Spikes cylindric, with 3-5 whorls of opposite flowers. Carpels 4. Fruit obovoid, 2.8-3.8 mm, abaxial keel distinct. Fl. and fr. Jul-Sep.
Heilongjiang, Jilin, Liaoning [Russia].
The Chinese record of Potamogeton acutifolius Link ex Roemer & Schultes in FRPS (8: 50-51. 1992) was based on a misidentification of P. mandschuriensis.