Page authors: Don Knoke, David Giblin
Equisetum fluviatile
river horsetail, swamp horsetail, water horsetail

Distribution: Occurring on both sides of the Cascades crest in Washington; Alaska to Oregon, east to the northern Rocky Mountains and northern Great Plains, Great Lakes region, and northeastern North America.

Habitat: Shallow water, marshes and bogs, along muddy shores, from the lowlands to moderate elevations in the mountains.

Spores: April-July

Origin: Native

Growth Duration: Perennial

Conservation Status: Not of concern


Rhizomatous annual, the stems not dimorphic, up to 1 m. tall, shallowly 9- to 25-ridged and grooved, the ridges smooth; stomata in a single broad band in each furrow; central cavity large, more than 3/4 the diameter of the stem; sheaths green, 4-9 mm. long, with persistent, sharp, black teeth 1.5-3 mm. long.


Branches none to many and whorled, 4- to 6-angled, simple, the first internode shorter than the stem sheath.


Cone short-pedunculate, blunt, deciduous.

Accepted Name:
Equisetum fluviatile L.
Publication: Sp. Pl. 2: 1062. 1753.

Synonyms & Misapplications:
Equisetum limosum L. [Peck]
Additional Resources:

PNW Herbaria: Specimen records of Equisetum fluviatile in the Consortium of Pacific Northwest Herbaria database

WA Flora Checklist: Equisetum fluviatile checklist entry

OregonFlora: Equisetum fluviatile information

E-Flora BC: Equisetum fluviatile atlas page

CalPhotos: Equisetum fluviatile photos

24 photographs:
Group by