Potamogeton groenlandicus |
Potamogeton perfoliatus |
|
---|---|---|
Greenland pondweed |
clasping-leaf pondweed, potamot perfolié |
|
Rhizomes | absent. |
present. |
Cauline stems | terete, without spots, 20–50 cm; glands white, 0.1–0.7 mm diam. |
terete, without spots, to 250 cm; nodal glands absent. |
Turions | terminal or axillary, common, 4.2–8.4 cm × 1.4–2.5 mm, soft; leaves ± 4-ranked; outer leaves 2 per side, base without corrugations, apex acute to apiculate; inner leaves unmodified. |
absent. |
Leaves | submersed, ± spirally arranged, sessile, delicate; stipules deliquescent to persistent, inconspicuous, convolute, free from blade, brown, not ligulate, 0.45–1.91 cm, not fibrous, not shredding at tip, apex obtuse; blade pale to deep green, linear, not arcuate, 2.6–8.8 cm × 0.7–1.7 mm, base slightly tapering, without basal lobes, not clasping, margins entire, not crispate, apex not hoodlike, acute to apiculate, lacunae absent or present, 0–3 rows each side of midrib; veins 7–11. |
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, erect, cylindric, 20 mm; spikes not dimorphic, cylindric, 5 mm. |
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 | not laterally keeled, 2.6–2.7 × 2 mm; beak erect, 0.3 mm; sides without basal tubercles; embryo with 1 full coil. |
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 | = 26. |
= 52. |
Potamogeton groenlandicus |
Potamogeton perfoliatus |
|
Phenology | Flowering late summer. | Flowering summer–fall. |
Habitat | Ponds and lakes | Waters, often brackish, of lakes, streams, rivers, and bays |
Elevation | 10–450 m (0–1500 ft) | 0–100 m (0–300 ft) |
Distribution |
Greenland |
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
|
Discussion | Of conservation concern. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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.) |
Source | FNA vol. 22. | FNA vol. 22. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | P. pusillus subsp. groenlandicus | |
Name authority | Hagström: Kongl. Svenska Vetenskapsakademiens Handlingar n.s. 55(5): 127. (1916) | Linnaeus: Sp. Pl. 1: 126. 1753 (as perfoliatum) |
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