Potamogeton perfoliatus |
Potamogeton subsibiricus |
|
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clasping-leaf pondweed, potamot perfolié |
potamot de l'ilenissei, Yenisei River pondweed, Yenissei River pondweed |
|
Cauline stems | terete, without spots, to 250 cm; nodal glands absent. |
compressed-filiform, without spots, to 50 cm; glands white, 0.3–0.5 mm diam. |
Turions | absent. |
lateral, common, 3.5–9.5 cm × 2–5 mm, soft; leaves ± 2-ranked; outer leaves 3–4 per side, base not corrugate; inner leaves undifferentiated. |
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. |
submersed, ± spirally arranged, sessile, flaccid; stipules deliquescent, inconspicuous, convolute, free from blade, pale brown, not ligulate, 1–2 cm, not fibrous, not shredding, apex obtuse; blade dark green, linear, not arcuate, 3.5–9.5 cm × 1.5–2 mm, base slightly tapering, without basal lobes, not clasping, margins entire, not crispate, apex not hoodlike, rounded or nearly acute to mucronate, lacunae in 1–2 rows each side of midvein; veins 9–17. |
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. |
unbranched, emersed; peduncles not dimorphic, axillary, erect, cylindric, 1.7–3.5 cm; spikes not dimorphic, cylindric, 10–30 mm. |
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. |
sessile, reddish brown, oblong-obovoid, compressed, abaxially ridged, not laterally keeled, 3–4 × 1.5–2 mm; beak nearly erect, 0.3–0.5 mm; sides without basal tubercles; embryo with 1 full coil. |
Rhizome(s) | present. |
absent. |
2n | = 52. |
|
Potamogeton perfoliatus |
Potamogeton subsibiricus |
|
Phenology | Flowering summer–fall. | Fruiting early summer–late summer. |
Habitat | Waters, often brackish, of lakes, streams, rivers, and bays | Shallow water of ponds and lakes |
Elevation | 0–100 m (0–300 ft) | 0–915 m (0–3000 ft) |
Distribution |
AL; CT; DC; DE; FL; LA; MA; MD; ME; NC; NH; NJ; NY; OH; PA; RI; VA; VT; NB; NL; NS; ON; PE; QC; SPM; Africa; Greenland; Eurasia; Central America (Guatemala); Australia
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AK; MB; NT; NU; ON; QC; YT; Siberia |
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. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Source | FNA vol. 22. | FNA vol. 22. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | P. porsildiorum | |
Name authority | Linnaeus: Sp. Pl. 1: 126. 1753 (as perfoliatum) | Hagström: Kongl. Svenska Vetenskapsakademiens Handlingar n.s. 44:555(5):84. (1916) |
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