Isoetes occidentalis
western quillwort

Distribution: Occurring chiefly west of the Cascades crest; Alaska to California, east to the Rocky Mountains.

Habitat: Submerged in ponds and lakes, often in deep water, from the lowland to middle elevations in the mountains.

Origin: Native

Growth Duration: Perennial

Conservation Status: Not of concern


Aquatic perennial, submerged; rootstock buried and corm-like, nearly globose, with 2 lobes, corky, brown.


Leaves evergreen, simple, in tufts somewhat resembling grass, spirally arranged on top of stem, erect to spreading, rigid and brittle, less than 20 cm, linear above base, tapered to apex, dark green with brown-white base.


Sporangia solitary, embedded in enlarged leaf base, less than 1 cm, less than 1/2 covered by a translucent membrane, male or female; male spores less than 10,000, 0.035-0.045 mm, somewhat bean-shaped, gray in mass; female spores 20-200, 0.5-0.7 mm, ridged, tubercled.

Accepted Name:
Isoetes occidentalis L.F. Hend.
Publication: Bull. Torrey Bot. Club. 27: 358. 1900.

Synonyms & Misapplications:
Isoetes flettii (A.A. Eaton) N.E. Pfeiff. [Abrams]
Isoetes lacustris L., misapplied [FNA2, HC]
Isoetes lacustris L. var. paupercula Engelm.
Isoetes paupercula (Engelm.) A.A. Eaton
Isoetes piperi A.A. Eaton [Abrams]
Additional Resources:

PNW Herbaria: Specimen records of Isoetes occidentalis in the Consortium of Pacific Northwest Herbaria database.

WA Flora Checklist: Isoetes occidentalis checklist entry.

E-Flora BC: Isoetes occidentalis atlas page.

CalPhotos: Isoetes occidentalis photos.

USDA Plants: Isoetes occidentalis information.

8 photographs:
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