Potamogeton strictifolius |
Potamogeton nodosus |
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narrowleaf pondweed, potamot à feuilles raides, stiff-leaf pondweed, straight-leaf pondweed |
loddon's pondweed, long-leaf pondweed, pondweed, potamot noeuex |
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Rhizomes | absent. |
present. |
Cauline stems | terete, without spots, 27–95 cm; glands white, green, greenish brown, or gold, to 0.3 mm diam. |
terete, without spots, to 100 cm; nodal glands absent. |
Turions | terminal or lateral, common, 2.5–4.8 cm × 0.8–2.2 mm, soft; leaves ± 2-ranked, flattened with outer and inner leaves in same plane; outer leaves 3–4 per side, base not corrugate, or rarely corrugate, apex acute; inner leaves undifferentiated. |
absent. |
Leaves | submersed, ± spirally arranged, rigid, sessile; stipules disintegrating, inconspicuous, connate, free from blade, white, not ligulate, 0.6–1.6 cm, fibrous, shredding at tip, apex obtuse; blade green to olive-green, linear, not arcuate, 1.2–6.3 cm × 0.6–2 mm, base slightly tapering, without basal lobes, not clasping, margins entire, not crispate, apex not hoodlike, acute to nearly bristle-tipped, rarely obtuse to apiculate, lacunae absent; veins 3–5(–7). |
both submersed and floating, or floating absent, ± spirally arranged. |
Floating leaves | petioles 3.5–26 cm; blade adaxially light green, lenticular to elliptic, 3–11 cm × 15–45 mm, base cuneate to rounded, apex acute to rounded; veins 9–21. |
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Submersed leaves | petiolate, lax; stipules persistent to deliquescent, conspicuous, convolute, free from blade, light brown, not ligulate, 3–9 cm, not fibrous, not shredding at tip, apex round to acute; petioles 2–13 cm; blade light to dark green, linear-lanceolate to lance-elliptic, not arcuate, 9–20 cm × 10–35 mm, base acute, without basal lobes, not clasping, margins entire, not crispate, apex not hoodlike, acute, without sharp awl-like tip, lacunae in 2–5 rows each side of midrib; veins 7–15. |
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Inflorescences | unbranched, emersed; peduncles not dimorphic, terminal, erect, rarely recurved, cylindric, rarely slightly clavate, 1–4.5 cm; spike not dimorphic, cylindric, 0.6–1.3 cm. |
unbranched, emersed; peduncles not dimorphic, terminal, erect to ascending, cylindric, 3–15 cm; spikes not dimorphic, cylindric, 20–70 mm. |
Fruits | sessile, green-brown, ovoid, turgid, not abaxially or laterally keeled, 1.9–2.1 × 1.3–1.8 mm; beak erect, 0.5–0.8 mm; sides without basal tubercles; embryo with 1 full spiral. |
sessile, red to reddish brown, obovoid, abaxially keeled, laterally ridged, 2.7–4.3 × 2.5–3 mm, keel well developed, lateral ridges with blunt to sharp tips; beak erect; sides without basal tubercles; embryo with 1 full spiral. |
2n | = 26. |
= 52. |
Potamogeton strictifolius |
Potamogeton nodosus |
|
Phenology | Flowering and fruiting summer–fall. | Flowering summer–fall. |
Habitat | Alkaline waters of lakes and slow-moving streams | Clear to turbid waters of lakes, streams, rivers, and sloughs |
Elevation | 50–2000 m (200–6600 ft) | 0–3300 m (0–10800 ft) |
Distribution |
CT; IL; IN; MA; ME; MI; MN; ND; NE; NY; OH; PA; SD; UT; VA; VT; WI; WY; AB; MB; NB; ON; QC; SK; YT
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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; NB; ON; QC; SK; Mexico; Central America; South America; West Indies; Eurasia
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Discussion | Potamogeton strictifolius is a relatively uncommon species found in alkaline waters. Fairly rigid leaves of the species make floating onto paper unnecessary in the collecting process. The leaves have a tendency to become revolute during the growing season. The species superficially resembles several other species of linear-leaved pondweeds. Consequently, many specimens of this species have been misidentified as other species and vice versa. Thus, literature records are often suspect. One hybrid, Potamogeton strictifolius × P. zosteriformis (= P. × haynesii Hellquist & G. E. Crow), has been described. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Six hybrids, Potamogeton gramineus × P. nodosus (= P. × argutulus Hagström), P. illinoensis × P. nodosus (= P. × faxonii Morong), P. nodosus × P. richardsonii (= P. × rectifolius A. Bennett), P. natans × P. nodosus (= P. × schreberi Fischer [P. × perplexus A. Bennett]), P. alpinus × P. nodosus (= P. × subotusus Hagström), and P. epihydrus × P. nodosus (= P. × subsessilis Hagström), have been described. Potamogeton nodosus is a common floating-leaved species throughout much of the United States and southern Canada. When both submersed and floating leaves are present, it is very easily recognized by the petioles of the submersed leaves being longer than 5 cm. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 22. | FNA vol. 22. |
Parent taxa | Potamogetonaceae > Potamogeton | Potamogetonaceae > Potamogeton |
Sibling taxa | ||
Synonyms | P. strictifolius var. rutiloides | |
Name authority | A. Bennett: J. Bot. 40: 148. (1902) | Poiret: in J. Lamarck et al., Encyclopedie Methodique. Botanique... Supplement 4(2): 5354. (1816) |
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