Potamogeton foliosus |
Potamogeton amplifolius |
|
---|---|---|
leafy pondweed |
broad-leaved pondweed, large-leaved pondweed |
|
Habit | Aquatic, herbaceous perennials from slender rhizomes, the stems freely branching, somewhat compressed and narrow winged, scarcely 1 mm. broad, up to 10 dm. long. | Aquatic, herbaceous perennials from slender rhizomes, the terete stems up to 4 mm. thick and 1 m. long, simple or sparingly branched above. |
Leaves | Leaves all submersed, without basal glands, narrowly linear, 1-1.5 mm. broad and up to 10 cm. long, acute, 3-nerved, bordered toward the base with air chambers; stipules united and surrounding the stem, 5-15 mm. long, ultimately disintegrating. |
Leaves alternate, the submersed leaves short-petiolate, the upper ones 8-20 cm. long and 2-5 cm. broad, acute at both ends, folded, and sickle-shaped in outline, 25- to 45-nerved; floating leaves with long, stout petioles, the blades leathery, ovate to ovate-elliptic, acute or rounded at the base, 5-10 cm long and 2-4 cm. broad; stipules to 10 cm. long, free of the petiole. |
Flowers | Inflorescence of spikes up to 5 mm. long with 2-3 whorls of crowded, sessile flowers; peduncles stout, rarely over 2 cm. long; perianth of 4 clawed segments, each with an upturned, oval blade; stamens 4, fused with the claws; pistils 4, sessile. |
Flowers perfect, in densely-flowered spikes on peduncles 7-15 cm. long; perianth of 4 clawed segments, each with an upturned, oval blade; stamens 4, fused with the claws; pistils 4, sessile. |
Fruits | Achenes obliquely obovoid, 2 mm. long, with a prominent dorsal keel. |
Achenes obliquely ovoid, 4-5 mm. long, with a sharp dorsal keel and 2 lateral keels. |
Potamogeton foliosus |
Potamogeton amplifolius |
|
Flowering time | June-August | June-August |
Habitat | Standing to moving, shallow water. | Lakes and ponds, tolerant of deep waters. |
Distribution | Occurring on both sides of the Cascades crest in Washington; Alaska to California, east across North America to the Atlantic Coast.
|
Occurring on both sides of the Cascades crest in Washington; British Columbia to California, east to the Atlantic Coast.
|
Origin | Native | Native |
Conservation status | Not of concern | Not of concern |
Sibling taxa | ||
Web links |
|
|