Potamogeton strictifolius |
Potamogeton oblongus |
|
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narrowleaf pondweed, potamot à feuilles raides, stiff-leaf pondweed, straight-leaf pondweed |
cinnamonspot pondweed, potamot oblong |
|
Cauline stems | terete, without spots, 27–95 cm; glands white, green, greenish brown, or gold, to 0.3 mm diam. |
terete, without spots, 5–30 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 only submersed, ± spirally arranged. |
Floating leaves | petioles continuous in color to apex, 1–17 cm; blade adaxially reddish brown, ovate, 3–8(–10) cm × 10–46 mm, base rounded or slightly cordate, apex obtuse, acute, or somewhat apiculate; veins (11–)15–19(–21). |
|
Submersed leaves | petiolate, lax; stipules persistent, conspicuous, convolute, free from blade, greenish, not ligulate, to 3 cm, not fibrous, not shredding at tip, apex acute; petioles 1–3(–8) cm; blade dark green, lanceolate to occasionally ovate, occasionally arcuate, 3–13 cm × 4–15(–44) mm, base acute, without basal lobes, not clasping, margins entire, not crispate, apex not hoodlike, acute, lacunae in 2–4 rows each side of midvein; veins 7–11. |
|
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, erect to slightly recurved, cylindric, 4–12 cm; spikes not dimorphic, cylindric, 20–40 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, dark reddish brown, obovoid to orbicularoid, compressed, not abaxially or laterally keeled, (1.6–)2–2.5 × (1.2–)1.5–2.1 mm; beak minute or obsolete, recurved; sides without basal tubercles; embryo with 1 full spiral. |
Rhizome(s) | absent. |
present. |
2n | = 26. |
= 26. |
Potamogeton strictifolius |
Potamogeton oblongus |
|
Phenology | Flowering and fruiting summer–fall. | Flowering July–August. |
Habitat | Alkaline waters of lakes and slow-moving streams | Acid to neutral waters of ponds, lakes, and occasionally streams |
Elevation | 50–2000 m (200–6600 ft) | 10–100 m (0–300 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
|
NF; NS; SPM; Europe; n Africa; Atlantic Islands (Azores) [Introduced in North America] |
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.) |
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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) | Viviani: Annali di Botanica 1(2): 102. (1802) |
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