Potamogeton foliosus subsp. fibrillosus |
Potamogeton foliosus |
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fibrous pondweed |
closed-leaf pondweed, leafy pondweed |
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Rhizomes | absent. |
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Stems | glands common, to 0.5 mm diam. |
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Cauline stems | slightly compressed, without spots, 4–75 cm; glands rarely present, black to gold, to 0.5 mm diam. |
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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. |
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Leaves | stipules brown or rarely white, fibrous, shredding at tip, veins in age remaining as fibers. |
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). |
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Inflorescences | spikes interrupted. |
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. |
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Fruits | pale -green, 1.4–1.7 × 1.1–1.2 mm; keel less than or equal to 0.2 mm high; beak less than or equal to 0.2 mm. |
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. |
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Chromosome number | unknownnot available. |
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Potamogeton foliosus subsp. fibrillosus |
Potamogeton foliosus |
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Phenology | Flowering and fruiting summer–fall. | |||||
Habitat | Warm waters of shallow lakes, springs, streams, and rivers | |||||
Elevation | 600–2700 m (2000–8900 ft) | |||||
Distribution |
CA; ID; OR; UT; WA; WY |
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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Discussion | Potammogeton foliosus subsp. fibrillosus is known from the warm waters of the northwestern United States. It differs from subsp. foliosus by the stipular tissue between the veins decomposing, leaving only strands formed by the fibrous veins. In addition, nodal glands are quite common. Of conservation concern. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Subspecies 2 (2 in the flora). (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 | ||||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | P. fibrillosus, P. foliosus var. fibrillosus | |||||
Name authority | (Fernald) R. R. Haynes & Hellquist: Novon 6: 370. (1996) | Rafinesque: Medical Repository hexade 2, 5:354. (1808) | ||||
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