Page author: Don Knoke
Potamogeton richardsonii
clasping-leaved pondweed, Richardson's pondweed

Distribution: Alaska to Maine, south to California and New Mexico in the west and Illimois in eastern United states; more common west of the Cascades in Washington

Habitat: Standing or slow-moving water

Flowers: June - August

Origin: Native

Conservation Status: Not of concern


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 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 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.


Achenes obliquely obovate, about 3 mm. long, faintly keeled on the back, with no lateral keels, the stylar beak nearly 1 mm. long.

Accepted Name:
Potamogeton richardsonii (A. Benn.) Rydb.
Publication: Bulletin of the Torrey Botanical Club. 32: 599. 1905. 1905.

Synonyms & Misapplications:
Potamogeton perfoliatus L. ssp. richardsonii (A. Benn.) Hultén
Potamogeton perfoliatus L. var. richardsonii A. Benn.
Additional Resources:

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

WA Flora Checklist: Potamogeton richardsonii checklist entry.

E-Flora BC: Potamogeton richardsonii atlas page.

CalPhotos: Potamogeton richardsonii photos.

USDA Plants: Potamogeton richardsonii information.

16 photographs:
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