Page author: Don Knoke
Potamogeton robbinsii
fern pondweed, Robbin's pondweed

Distribution: Alaska to California, east to Montana and Colorado; Minnesota to Maine, south to Virginia in eastern United States

Habitat: Quiet water, mostly in lakes

Flowers: August - September

Origin: Native

Conservation Status: Not of concern


Aquatic, herbaceous perennials from slender rhizomes, the stems terete, stout, branching, 1-4 dm. long.


Leaves alternate, submersed, linear-lanceolate, up to 12 cm. long, mostly 3-4 mm. broad, acute, finely serrulate, with a broad mid-nerve and 20-35 very fine lateral nerves, stiffly 2-ranked and crowded on the stem; stipules fused to the leaf bases for 10-15 mm., the free portion longer, white.


Stem freely-branching in the inflorescence, with many peduncles 3-5 cm. long; flowers perfect, in spikes 7-20 mm. long on the peduncles; perianth of 4 clawed segments, each with an upturned, oval blade; stamens 4, fused with the claws; pistils 4, sessile.


Achenes obovoid, 3.5-4 mm. long, with a sharp dorsal keel and rounded lateral keels, and without a beak.

Accepted Name:
Potamogeton robbinsii Oakes
Publication: Magazine of horticulture, botany and all useful discoveries and improvements in rural affairs. 7: 180. 1841. 1841.

Synonyms & Misapplications:
(none provided)
Additional Resources:

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

WA Flora Checklist: Potamogeton robbinsii checklist entry.

E-Flora BC: Potamogeton robbinsii atlas page.

CalPhotos: Potamogeton robbinsii photos.

USDA Plants: Potamogeton robbinsii information.

5 photographs:
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