Page author: Don Knoke
Potamogeton pusillus
small pondweed

Distribution: British Columbia south on both sides of the Cascades to California, east to the Atlantic.

Habitat: Shallow ponds and streams.

Flowers: July - August

Origin: Native

Conservation Status: Not of concern


Aquatic, herbaceous perennials from slender rhizomes, the stems very slender, freely branched, up to 10 dm. long.


Leaves alternate, submersed, narrowly linear, up to 7 cm. long and 0.5-2 mm. broad, 3-nerved, acute, bordered at the base with small, globose glands; stipules 6-15 mm. long, surrounding the stem for half their length.


Flowers perfect, in spikes 3-15 cm. long but with only 1-3 whorls, on very slender peduncles 1.5-4 cm. long; perianth of 4 clawed segments, each with an upturned, oval blade; stamens 4, fused with the claws; pistils 4, sessile.


Achenes obliquely obovoid, about 2 mm. long, not keeled, the stylar beak 0.5 mm. long, slightly recurved.

Accepted Name:
Potamogeton pusillus L.
Publication: Sp. Pl. 1: 127. 1753 (as pusillum).

Synonyms & Misapplications:
Potamogeton panormitanus Biv.
Potamogeton pusillus L. ssp. pusillus [FNA22]
Potamogeton pusillus L. var. minor (Biv.) Fernald & B.G. Schubert
Potamogeton pusillus L. var. pusillus [JPM]
Additional Resources:

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

WA Flora Checklist: Potamogeton pusillus checklist entry.

E-Flora BC: Potamogeton pusillus atlas page.

CalPhotos: Potamogeton pusillus photos.

USDA Plants: Potamogeton pusillus information.

7 photographs:
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