Potamogeton hillii |
Potamogeton pulcher |
|
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Hill's pondweed |
heartleaf pondweed, potamot gracieux, spotted pondweed |
|
Rhizomes | absent. |
present. |
Cauline stems | slightly compressed, without spots, 30–60 cm; glands rare, when present, brown to green, 0.1–0.3 mm diam. |
terete, conspicuously spotted, 8–95 cm; nodal glands absent. |
Turions | terminal, rare, 2.8–3 cm × 1.5–3 mm, soft; leaves ± 2-ranked; outer leaves 3–4 per side, base not corrugate, apex acute to apiculate; inner leaves undifferentiated. |
absent. |
Leaves | submersed, ± spirally arranged, sessile, delicate; stipules persistent, inconspicuous, convolute, free from blade, white to light brown, not ligulate, 0.7–1.6 cm, slightly fibrous, rarely shredding at tip, apex obtuse; blade pale green to olive-green, linear, not arcuate, 2–6 cm × 0.6–2.5(–4) mm, base slightly tapering, without basal lobes, not clasping, margins entire, not crispate, apex not hoodlike, apiculate to bristle-tipped or rarely blunt, lacunae in 1–2 rows each side of midrib; veins 3. |
both submersed and floating, ± spirally arranged. |
Floating leaves | petioles continuous in color to apex, 1–16.5 cm; blade adaxially light to dark green, lanceolate to round-ovate, 2.5–8.5 cm × 11–44 mm, base rounded to cordate, apex acute to rounded; veins 15–21. |
|
Submersed leaves | petiolate, lax; stipules deliquescent, inconspicuous, convolute, free from blade, light to dark brown, not ligulate, 0.7–1.2 cm, not fibrous, not shredding at tip, apex obtuse; petioles 0.5–4.5 cm; blade dark green, linear-lanceolate to lanceolate, often arcuate, 3.5–13.8 cm × 60–165 mm acute, base acute to rounded, without basal lobes, margins entire, crispate, apex not hoodlike, acute to obtuse, lacunae in 2–5 rows each side of midrib; veins 7–19. |
|
Inflorescences | unbranched, emersed; peduncles not dimorphic, axillary and/or terminal, erect to ascending, rarely recurved, slightly clavate, 6–13.5 mm; spikes not dimorphic, globose, (2–) 4–7 mm. |
unbranched, emersed; peduncles not dimorphic, terminal or axillary, erect to ascending, cylindric, 3.3–9.4 cm; spikes not dimorphic, cylindric, 17–36 mm. |
Fruits | brown to light greenish brown, ovoid to orbicular, turgid, sessile, abaxially and laterally keeled (3-keeled), 2.3–4 × 2–3.2 mm, lateral keels without points; beak erect, 0.3–0.7 mm; sides without basal tubercles; embryo with 1 full spiral. |
sessile, dark green to dark brown, ovoid to obovoid, turgid, abaxially keeled, laterally ridged, 5–6.5 × 4.1–5 mm, lateral ridges without points; beak erect, 0.5 mm; embryo with 1 full spiral. |
Chromosome number | unknownnot available. |
apparently unknown not available. |
Potamogeton hillii |
Potamogeton pulcher |
|
Phenology | Flowering and fruiting summer. | Flowers summer–fall. |
Habitat | Alkaline waters of marshes, ponds, lakes, and slow-moving streams | Stagnant to slow-flowing waters of streams, lakes, ponds, and small rivers |
Elevation | 50–400 m (200–1300 ft) | 0–700 m (0–2300 ft) |
Distribution |
CT; MA; MI; NY; OH; PA; VA; VT; WI; ON
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AL; AR; CT; DE; FL; GA; IL; IN; KY; LA; MA; MD; ME; MI; MN; MO; MS; NC; NH; NJ; NY; OH; OK; PA; RI; SC; TN; TX; VA; WI; WV; NB; NS; PE; Ont
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Discussion | Potamogeton hillii is an easily recognized species either in fruit or when sterile. The leaf blade has a bristle tip and five or fewer veins. Those characters combined with the usual absence of nodal glands will separate this species from all other North American linear-leaved species. Ecologically, it is consistently found in more alkaline waters than any other North American pondweed. A study of 35 localities established the mean to be 124.1 mg/l CaCO3 (C. B. Hellquist 1984). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Potamogeton pulcher is similar in morphology to P. amplifolius and occurs in similar habitats. Potamogeton pulcher differs from P. amplifolius by the former having lanceolate to linear-lanceolate submersed leaves with fewer than 19 veins, whereas the latter has ovate submersed leaves with more than 19 veins. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 22. | FNA vol. 22. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | P. porteri | |
Name authority | Morong: Botanical Gazette 6: 290, fig. 3. (1881) | Tuckerman: American Journal of Science, and Arts 45:38. (1843) |
Web links |