Potamogeton alpinus |
Potamogeton diversifolius |
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northern pondweed, reddish pondweed |
diverse-leaved pondweed, water-thread pondweed |
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Stems | terete; to 200 cm; nodal glands absent. |
compressed, 10–35 cm; nodal glands absent. |
Leaves | submersed and floating or submersed only. |
both submersed and floating or submersed only. |
Floating leaves | elliptic or oblanceolate to obovate or oblonglinear, 40–70(100) × 10–25(40)mm; reddish green; base gradually tapering to petiole; tip obtuse or acute; veins (7)9–13(15); petioles 0–12 mm. |
obovate to elliptic; (10)15–30 × 3–8.5 mm, light green; base acute; tip round to acute; veins 3–7; petioles 7–8 mm. |
Submersed leaves | sessile, attached to stem nodes, not attached to stipules; stipules (12)15–25(40)mm; tip blunt; blades oblong-linear to linear-lanceolate, 45–180(250) × 5–20 mm; base rounded to cuneate; margins entire; tip obtuse or acute; lacunae in 0–6 rows on each side of midvein; veins 7–9. |
sessile with blade attached to stipule near middle; stipules persistent to decomposing, ligulate, 15–23 mm; tip obtuse; blades linear, often falcate, 20–40 × 0.5– 1(1.5) mm; base slightly tapering; margins entire; tip acute; lacunae in 1–2 rows on each side of midrib; vein 1. |
Inflorescences | emersed; spikes cylindric, 10–35 mm; peduncles terminal or axillary; erect, 30– 100(160)mm. |
submersed spikes capitate, 2–3 mm, emersed spikes cylindric, 5–9.7 mm; peduncles axillary, recurved, 3–5 mm, emersed peduncles axillary or terminal; erect to slightly recurved, 6–15 mm. |
Fruits | pedicellate, obovoid; turgid; (2.5)3–3.5 × (1.7)2–2.4 mm, dorsally keeled, laterally keeled or not; beaks dorsally curved, 0.5–0.9 mm. |
sessile, orbicular, compressed, 1–1.5 × 0.9–2 mm; greenish brown, dorsally and laterally winged; lateral wings with sharp points; beaks erect, 0.1 mm. |
Potamogeton alpinus |
Potamogeton diversifolius |
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Distribution | ||
Discussion | Ponds, lakes, and slow-moving streams. 1200–2200m. BR, BW, Casc. CA, ID, NV, WA; north to British Columbia, east to Greenland; Eurasia. Native. Potamogeton alpinus is often red when fresh. This species hybridizes with P. nodosus, P. gramineus, and P. praelongus. |
Ponds, lakes, streams. 1100–1800m. BR, Owy. CA, ID, NV; east to CT, Mexico. Native. |
Source | Flora of Oregon, volume 1, page 496 Nick Otting, Richard Brainerd, Barbara Wilson |
Flora of Oregon, volume 1, page 497 Nick Otting, Richard Brainerd, Barbara Wilson |
Sibling taxa | ||
Synonyms | Potamogeton alpinus ssp. tenuifolius, Potamogeton alpinus var. subellipticus, Potamogeton alpinus var. tenuifolius | |
Web links |
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