Potamogeton alpinus |
Potamogeton richardsonii |
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northern pondweed, reddish pondweed |
clasping-leaved pondweed, Richardson's 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 sparingly branched, greenish, 1-2 mm. broad and 3-6 dm. long, the internodes only 1-3 cm. long. |
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 alternate, submersed, the blades sessile and clasping, ovate-lanceolate to lanceolate, up to 10 cm. long and 2 cm. broad, with crisp margins, 13-to 25-veined, rounded to acute; stipules free of the leaf, 1-2 cm. long, soon shredding into numerous whitish fibers. |
Flowers | Inflorescence generally < 3 cm, floating to emergent; peduncle stiff. |
Flowers perfect, in 6-12 closely compact whorls, in a spike 1.5-4 cm. long, on a stout peduncle 2-10 cm. 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 obliquely obovate, about 3 mm. long, faintly keeled on the back, with no lateral keels, the stylar beak nearly 1 mm. long. |
Potamogeton alpinus |
Potamogeton richardsonii |
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Flowering time | June-August | June-August |
Habitat | Calm water of lakes and slow streams. | Standing or slow-moving water. |
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, northern Great Plains, Great Lakes region, and northeastern 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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