Potamogeton praelongus |
Potamogeton natans |
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white-stalked pondweed, white-stemmed pondweed |
floating-leaf pondweed |
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Stems | terete; to 210 cm; nodal glands absent. |
terete, 30–90 cm; nodal glands absent. |
Leaves | submersed, sessile, attached at stem nodes, not attached to stipules; stipules 30– 81 mm, fibrous, shredding at tip; blades linear-lanceolate, 50–200 × 10–30 mm; base clasping but without basal lobes, rarely wavy; tip obtuse; veins 11–33. |
submersed and floating. |
Floating leaves | elliptic to ovate, 35–110 × 15–60 mm; base rounded to cordate; tip acute to rounded; veins 17–37; petioles 55–290 mm. |
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Submersed leaves | sessile, attached to stem nodes, not attached to stipules; stipules 45–100 mm; whitish, fibrous; tip obtuse; blades rigid, linear, subterete, 9–20 cm × 0.7–2.5 mm; base slightly tapering; margins entire; tip obtuse; veins 3–5, obscure. |
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Inflorescences | emersed; spikes cylindric, 34–75 mm; peduncles terminal or axillary; erect to spreading, 10–30 cm. |
emersed; spikes cylindric, 25–50 mm; peduncles terminal; erect to ascending, 45–95 mm. |
Fruits | sessile, obovoid; turgid, 4–5.7 × 3.2–4 mm; greenish brown, dorsally keeled, occasionally laterally keeled; beaks erect, 0.6–1 mm. |
sessile, obovoid; turgid, 3.5–5 × 2–3 mm, green to greenish brown, not keeled; beaks erect to apically recurved, 0.4–0.8 mm. |
Potamogeton praelongus |
Potamogeton natans |
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Distribution | ||
Discussion | Neutral to alkaline waters of lakes and streams. 0–1900m. BW, Est. CA, ID; north to British Columbia, east to Newfoundland, south to Mexico; Eurasia. Native. This species hybridizes with P. alpinus, P. crispus and P. gramineus. |
Ponds, lakes, and slow-moving streams. 0–2000 m. BR, BW, Casc, CR, ECas, Est, WV. CA, ID, NV, WA; north to Northwest Territories, east to Newfoundland, southeast to NM; Eurasia. Native. Potamogeton natans is a common pondweed of still or slow moving water. Its leathery floating leaves are often cordate at the base. Its petioles have reflexed tips with a light-colored band that contrasts with darker tissue below. Its submersed leaves are rigid and subterete. This species hybridizes with P. nodosus. |
Source | Flora of Oregon, volume 1, page 499 Nick Otting, Richard Brainerd, Barbara Wilson |
Flora of Oregon, volume 1, page 499 Nick Otting, Richard Brainerd, Barbara Wilson |
Sibling taxa | ||
Web links |
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