Potamogeton alpinus |
Potamogeton praelongus |
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northern pondweed, reddish pondweed |
white-stalked pondweed, whitestem pondweed |
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Habit | Annual, perennial herb, slender, rhizomed; stems greater than 100 cm, branched, branches not many, cylindric. | Aquatic, herbaceous perennials from slender rhizomes, the stems up to 3 m. long, sparingly branched, slightly flattened, 2-3 mm. thick, whitish, the shorter internodes zigzag. |
Leaves | Various shades of red; submersed sessile, 2-8 x 1-2 cm, lanceolate to elliptic-oblong, tapered to both ends, entire, tip blunt, veins 7-9; floating 0 or short-petioled, lanceolate, base tapered, veins 7-15; stipules beyond 3 cm, free, membranous, early-deciduous. |
Leaves all submersed, the blades sessile, with a clasping base, oblong-lanceolate, 1-2.5 dm. long and 2-3 cm. broad, entire, the tip rounded and somewhat hooded; stipules free of the blade, 4-10 cm. long, whitish. |
Flowers | Inflorescence generally < 3 cm, floating to emergent; peduncle stiff. |
Flowers perfect, in dense spikes 2.5-5 cm. long; peduncles club-shaped, 1-3 dm. long; perianth of 4 clawed segments, each with an upturned, oval blade; stamens 4, fused with the claws; pistils 4, sessile. |
Fruit(s) | Around 2.5 mm, keels 1 or 3, generally, beaked, sides concave to convex. |
Achenes obovoid, 4-5 mm. long, with a short beak and prominent dorsal keel. |
Potamogeton alpinus |
Potamogeton praelongus |
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Flowering time | June-August | May-July |
Habitat | Calm water of lakes and slow streams. | Deep water of lakes. |
Distribution | Occurring on both sides of the Cascades crest in Washington; Alaska to California, east to the Rocky Mountains and northern Great Plains; also in eastern North America.
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Occurring on both sides of the Cascades crest in Washington; Alaska to California, east to the Rocky Mountains, Great Plains, Great Lakes region, and eastern North America.
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Origin | Native | Native |
Conservation status | Not of concern | Not of concern |
Sibling taxa | ||
Web links |
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