Perfoliate Pondweed

Flowering and fruiting from June to August.

Potamogeton perfoliatus is close relative of Potamogeton praelongus, but differs from the latter in its rhizomes unspotted (vs. spotted rusty-red), leaves ovate or ovate-oblong to lanceolate (vs. linear-lanceolate to ovate-oblong), minutely denticulate (vs. entire), apex flat, not splitting when pressed (vs. cucullate and splitting when pressed), stipules 3-22 mm (vs. 10-88 mm).

Potamogeton perfoliatus is occurring in Gansu, Guizhou, Hebei, Heilongjiang, Henan, Hubei, Hunan, Jilin, Liaoning, Nei Mongol, Qinghai, Shandong, Shanxi, Xinjiang, Xizang, Yunnan of China, India, Japan, Korea, Pakistan, Russia; Cosmopolitan: Africa, Asia, Australia, Europe, Central and North America.

Sequences of the chloroplast trnT-trnF region were analyzed for the species of the genus Potamogeton distributed in China to reconstruct phylogenetic relationships (Zhang et al., 2008). The phylogenetic analyses showed that the genus Potamogeton could be divided into two clades, supporting the conventional treatment that the genus Potamogeton contains the submerged linear-leaved group and the submerged broad-leaved group. The first clade represented the subgenus Potamogeton. The second clade, which represented the subgenus Coleogeton, displayed a close phylogenetic relationship with the subgenus Potamogeton and occupied a unique position within the genus Potamogeton.

Plants perennial, submerged in freshwater. Rhizome unspotted, terete, slender. Stems densely branched at upper part, terete, 0.5-2.5 mm in diameter. Stipules axillary, convolute, 3-22 mm, membranous, evanescent. Leaves sessile; leaf blade lanceolate to broadly ovate, orbicular-ovate, or ovate-oblong to lanceolate, 3-5-veined, with narrow rows of lacunae bordering midvein, base cordate and amplexicaul, margin minutely denticulate, apex obtuse or rounded. Spikes usually contiguous and cylindrical, with 4-7 whorls of opposite flowers; peduncles 2-11 cm. Carpels 4. Fruit obovoid, 2.5-4.5 mm; abaxial keels 3, with a slightly sharp midvein and two indistinct lateral keels, with a short beak at tip.

The chromosomal number of Potamogeton perfoliatus is 2n = 52, 78 (Probatova and Sokolovskaya, 1986; Váchová and Feráková, 1986).

Growing in lakes, ponds, rivers, channels.