Page author: Don Knoke
Potamogeton epihydrus
ribbon-leaved pondweed

Distribution: Alaska south on both sides of the Cascades to California, east to Newfoundland and northeastern United States.

Habitat: Shallow to deep water.

Flowers: June - July

Origin: Native

Conservation Status: Not of concern


Aquatic, perennial herbs from slender rhizomes, the stems somewht flattened, simple or sparingly branched, 5-15 dm. long.


Submersed leaves linear, sessile, 10-20 cm. long and 3-10 mm. broad, the mid-vein bordered by rows of air chambers; floating leaves with flattened petioles shorter than the blade, the blades firm, elliptic to oblong-elliptic, 4-8 cm. long and 10-20 mm. broad, 15- to 25-nerved; stipules free, 1-3 cm. long, blunt.


Flowers in dense spikes 2-4 cm. long, on peduncles 3-8 cm. long; perianth of 4 clawed segments, each with an upturned, oval blade; stamens 4, fused with the claws; pistils 4, sessile.


Achenes obliquely and broadly obovate, 3-4 mm. long, sharply keeled on the back.

Accepted Name:
Potamogeton epihydrus Raf.
Publication: Medical Repository. 5: 354. 1808, hexade hexade 2; 3; 2:409. 1811. 1808.

Synonyms & Misapplications:
Potamogeton epihydrus Raf. ssp. nuttallii (Cham. & Schltdl.) Calder & Roy L. Taylor [JPM]
Potamogeton epihydrus Raf. var. nuttallii (Cham. & Schltdl.) Fernald [VPPNW1]
Potamogeton epihydrus Raf. var. ramosus (Peck) House
Additional Resources:

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

WA Flora Checklist: Potamogeton epihydrus checklist entry.

E-Flora BC: Potamogeton epihydrus atlas page.

CalPhotos: Potamogeton epihydrus photos.

USDA Plants: Potamogeton epihydrus information.

19 photographs:
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