Page author: Don Knoke
Potamogeton amplifolius
broad-leaved pondweed, large-leaved pondweed

Distribution: British Columbia to Newfoundland, south to California in the west and Alabama in the eastern United States, but absent from Nevada to Texas; common west of the Cascades in Washington

Habitat: Generally in fairly deep water

Flowers: June - August

Origin: Native

Conservation Status: Not of concern


Aquatic, herbaceous perennials from slender rhizomes, the terete stems up to 4 mm. thick and 1 m. long, simple or sparingly branched above.


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 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.


Achenes obliquely ovoid, 4-5 mm. long, with a sharp dorsal keel and 2 lateral keels.

Accepted Name:
Potamogeton amplifolius Tuck.
Publication: American Journal of Science, and Arts. ser. 2, 6:225. 1848. 1848.

Synonyms & Misapplications:
(none provided)
Additional Resources:

PNW Herbaria: Specimen records of Potamogeton amplifolius in the Consortium of Pacific Northwest Herbaria database.

WA Flora Checklist: Potamogeton amplifolius checklist entry.

E-Flora BC: Potamogeton amplifolius atlas page.

CalPhotos: Potamogeton amplifolius photos.

USDA Plants: Potamogeton amplifolius information.

18 photographs:
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