Potamogeton foliosus |
Potamogeton confervoides |
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closed-leaf pondweed, leafy pondweed |
alga pondweed, alga-like pondweed, potamot confervoide, Tuckerman's pondweed |
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Rhizomes | absent. |
obvious. |
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Cauline stems | slightly compressed, without spots, 4–75 cm; glands rarely present, black to gold, to 0.5 mm diam. |
terete, without spots, 10–80 cm. |
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Turions | uncommon, lateral or terminal, 0.9–2.5 cm × 0.6–2 mm, soft; outer leaves 1–3 per side, base not corrugate, apex acute to apiculate; inner leaves rolled into hardened fusiform structure. |
present, in axils of old leaves and from disintegrating branches, fusiform, 0.7–2 cm, leaves spreading to ascending. |
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Leaves | submersed, ± spirally arranged, sessile, delicate; stipules persistent, inconspicuous, convolute, free from blade, greenish to brown or rarely white, not ligulate, 0.2–2.2 cm, delicate to fibrous, rarely shredding at tip, apex obtuse; blade pale green to olive-green, rarely somewhat reddish, linear, not arcuate, 1.3–8.2 cm × 0.3–2.3 mm, base slightly tapering, without basal lobes, not clasping, margins entire, not crispate, apex not hoodlike, acute to apiculate, rarely with bristle, lacunae rarely present, 0–2 rows each side of midrib; veins 1–3(–5). |
submersed, ± spirally arranged, flaccid, sessile; stipules deliquescent, inconspicuous, convolute, free from blade, pale green, not ligulate, 0.5–1.2 cm, not fibrous, not shredding at tip, apex obtuse; blade pale green, linear, not arcuate, 1.8–6.5 cm × 0.1–0.5 mm, base slightly tapering, without basal lobes, not clasping, margins entire, not crispate, apex not hoodlike, extremely attenuate, bristly, lacunae present, each side of midvein to margins; veins 1. |
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Inflorescences | unbranched, emersed; peduncles not dimorphic, in axils of proximal, rarely distal leaves, recurved, clavate, 0.3–1.1(–3.7) cm; spikes not dimorphic, capitate to cylindric, 1.5–7 mm. |
unbranched, emersed; peduncles not dimorphic, terminal, ascending, somewhat clavate, (3–)5–25 cm; spikes not dimorphic, capitate, 5–12 mm. |
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Fruits | pale green to olive-green or brown, obovate to nearly orbicular, turgid to concave, sessile, abaxially keeled, not laterally keeled, 1.4–2.7 × 1.1–2.2 mm, abaxial keel undulate, winglike; beak erect, 0.2–0.6 mm; sides without basal tubercles; embryo with 1 full spiral. |
sessile, light green, round-obovoid or nearly orbicular, compressed, abaxially and laterally keeled, 2–3 × 1.7–2.8 mm, lateral keels without sharp point; beak erect, 0.5 mm; sides without basal tubercles; embryo with less than 1 full spiral. |
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Chromosome number | apparently unknown not available. |
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Potamogeton foliosus |
Potamogeton confervoides |
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Phenology | Flowering early–late summer. | |||||
Habitat | Acidic waters of bogs, ponds, and lakes, often at higher elevation in e portion of range | |||||
Elevation | 0–1500 m (0–4900 ft) | |||||
Distribution |
AK; AL; AR; AZ; CA; CO; CT; DC; DE; FL; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; MT; NC; ND; NE; NH; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SC; SD; TN; TX; UT; VA; VT; WA; WI; WV; WY; AB; BC; MB; NB; NS; NT; ON; PE; QC; SK; YT; Central America
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CT; MA; ME; MI; NC; NH; NJ; NY; PA; RI; SC; VT; WI; NB; NL; NS; ON; QC; SPM; St Pierre
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Discussion | Subspecies 2 (2 in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Potamogeton confervoides is most uncommon and found only in fairly acidic waters. It is easily recognized by its linear, bristly leaves and the unusually long peduncle that seems out of place on a plant with such fine leaves. The leaves are so fine that they almost appear as greenish colored hair in the water. When the plant is removed from the water, the leaves are extremely flaccid leaves and essentially collapse onto each other. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 22. | FNA vol. 22. | ||||
Parent taxa | Potamogetonaceae > Potamogeton | Potamogetonaceae > Potamogeton | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | P. tuckermanii | |||||
Name authority | Rafinesque: Medical Repository hexade 2, 5:354. (1808) | Reichenbach: in H. G. L. Reichenbach et al., Icones florae germanicae et helveticae 7: 13. (1845) | ||||
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