Potamogeton alpinus |
Potamogeton fibrillosus |
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northern pondweed, reddish pondweed |
fibrous-stipuled pondweed |
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Habit | Annual, perennial herb, slender, rhizomed; stems greater than 100 cm, branched, branches not many, cylindric. | Herbaceous wetland perennial; stems commonly with glands, to 0.5 mm diameter, cauline stems somewhat compressed; turions uncommon, when present may be lateral or terminal, up to 2.5 cm long and 2 mm broad. |
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 submersed, generally spirally arranged, sessile; stipules inconspicuous, usually brown or uncommonly white, 0.2-2.2 cm, free from blade, fibrous and shredding at tip, veins persisting as fibers with age; blade light to olive green, uncommonly tinged red, linear, not curved, 1.3-8.2 cm long and 0.3-2.3 mm broad, base somewhat tapering, basal lobes absent and not clasping, margins entire and not wavy, apex not hoodlike, acute to apiculate, uncommonly bristle-tipped, lacunae rarely present, when present 0-2 rows on each side of midrib, veins usually 1-3. |
Inflorescence | Inflorescence a capitate to cylindric interrupted spike, up to 7 mm, unbranched, above water; peduncles emerging from axils of leaves nearest base, rarely from axils of distal leaves, curved backward, clavate, typically 0.3-1.1 cm. |
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Flowers | Inflorescence generally < 3 cm, floating to emergent; peduncle stiff. |
Tepals 4, in 1 series; stamens usually 4, with distinct anthers dehiscing vertically, pollen spheric; pistils 1 or 4, usually lacking stipes but sometimes short-stipitate. |
Fruit(s) | Around 2.5 mm, keels 1 or 3, generally, beaked, sides concave to convex. |
Drupes obovate to nearly orbicular, 1.4-1.7 mm long and 1.1-1.2 mm broad, light green; keeled beneath, 0.2 mm or less; beak erect, 0.2 mm high or less. |
Potamogeton alpinus |
Potamogeton fibrillosus |
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Flowering time | June-August | June-August |
Habitat | Calm water of lakes and slow streams. | Warm, shallow water, lakes, springs, streams. |
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 west of the Cascades crest in Washington; Washington to California, east to Idaho, Wyoming, and Utah. |
Origin | Native | Native |
Conservation status | Not of concern | Review Group 1 in Washington (WANHP) |
Sibling taxa | ||
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