Potamogeton perfoliatus

Rhizomes present. Cauline stems terete, without spots, to 250 cm; nodal glands absent. Turions absent. Leaves submersed, ± spirally arranged, sessile, lax; stipules deteriorating into fibers and deciduous, inconspicuous (absent on proximal portion of stem), convolute, free from blade, light brown to green, not ligulate, 3.5–6.5 cm, not fibrous, not shredding at apex; blade olive-green, broadly lanceolate, orbiculate, or ovate, not arcuate, 0.9–7.6(–9.7) cm × 7–40 mm, base rounded, without basal lobes, clasping, margins entire, often crispate, apex not hoodlike, not splitting when pressed, round, rarely acute; veins 3–25. Inflorescences unbranched, emersed; peduncles not dimorphic, terminal or axillary, erect to rarely recurved, cylindric, 1–7.3 cm; spike not dimorphic, cylindric, 0.4–4.8 cm. Fruits sessile, greenish brown to olive-green, obovoid, turgid or rarely concave, not abaxially or laterally keeled, 1.6–3 × 1.3–2.2 mm; beak erect, 0.4–0.6 mm; sides without basal tubercles; embryo with 1 full spiral. 2n = 52.

Phenology: Flowering summer–fall.
Habitat: Waters, often brackish, of lakes, streams, rivers, and bays
Elevation: 0–100 m

Distribution

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• Legacy Map

Greenland, St. Pierre and Miquelon, N.B., Nfld. and Labr., N.S., Ont., P.E.I., Que., Ala., Conn., Del., D.C., Fla., La., Maine, Md., Mass., N.H., N.J., N.Y., N.C., Ohio, Pa., R.I., Vt., Va., Central America (Guatemala), Eurasia, Africa, Australia.

Discussion

Four hybrids, Potamogeton perfoliatus × P. praelongus (= P. × cognatus Ascherson & Graebner), P. perfoliatus × P. pusillus (= P. × mysticus Morong), P. gramineus × P. perfoliatus (= P. × nitens Weber [P. × subnitens Hagström]), and P. alpinus × P. perfoliatus (= P. × prussicus Hagström), have been described.

Selected References

None.

Lower Taxa

None.