Potamogeton alpinus |
Potamogeton gramineus |
|
---|---|---|
northern pondweed, reddish pondweed |
variable pondweed |
|
Stems | terete; to 200 cm; nodal glands absent. |
terete to flattened; to 150 cm; nodal glands absent. |
Leaves | submersed and floating or submersed only. |
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. |
elliptic to ovate, 35–40 × 16–20 mm, yellow-green to dark green; base rounded; tip acuminate; veins 11–13; petioles 30–45 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 or rarely petiolate, attached to stem nodes, not attached to stipules; stipules 10– 16 mm; tip acute to obtuse; blades linear to narrowly lanceolate or oblanceolate, 31–91 × 3–27 mm; base attenuate; margins entire, rarely wavy; tip acuminate; lacunae in 1–2 rows on each side of midvein; veins 3–7(9); petioles to 30 mm. |
Inflorescences | emersed; spikes cylindric, 10–35 mm; peduncles terminal or axillary; erect, 30– 100(160)mm. |
emersed; spikes cylindric, 15–35 mm; peduncles axillary and terminal; erect to ascending, cylindric, 32–77 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; ovoid, laterally compressed, 1.9–2.3 × 1.8–2 mm; greenish brown, dorsally and laterally keeled; beaks erect, 0.3–0.5 mm. |
Potamogeton alpinus |
Potamogeton gramineus |
|
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 and streams. 50–2300m. BR, BW, Casc, ECas, Est, WV. CA, ID, NV, WA; north to Northwest Territories, east to Newfoundland, southeast to AZ; Eurasia. Native. This species hybridizes with P. alpinus, P. illinoensis, P. natans, P. nodosus, P. praelongus, and P. richardsonii. |
Source | Flora of Oregon, volume 1, page 496 Nick Otting, Richard Brainerd, Barbara Wilson |
Flora of Oregon, volume 1, page 498 Nick Otting, Richard Brainerd, Barbara Wilson |
Sibling taxa | ||
Synonyms | Potamogeton alpinus ssp. tenuifolius, Potamogeton alpinus var. subellipticus, Potamogeton alpinus var. tenuifolius | Potamogeton gramineus var. gramineus, Potamogeton gramineus var. maximus, Potamogeton gramineus var. myriophyllus, Potamogeton heterophyllus |
Web links |
|
|