Page author: Don Knoke
Cyperus eragrostis
tall flatsedge
WTU specimens
Other herbaria

Distribution: British Columbia south to California, east to New Jersey and South Carolina.

Habitat: Damp grasslands and roadside ditches at low elevations.

Flowers: June - August

Origin: Introduced

Conservation Status: Not of concern


Tufted, herbaceous perennial from rhizomes, the culms terete to triangular, 40-60 cm. tall, glabrous.


Leaves flat or v-shaped, 25-50 cm. long and 5-8 mm. wide.


Inflorescence of globose heads 20-40 mm. in diameter; rays 3-10, 2.5-5 cm. long; bracts 4-8, horizontal to ascending, usually flat; spikelets 30-50, oblong, compressed; scales 20-30, off-white to golden brown, ovate-deltate, 2-2.3 mm. long; stamen 1; styles 1-1.2 mm. long.


Achenes dark brown to black, broadly ellipsoid, 1.2-1.4 mm. long, with a beak up to 0.3 mm. long.

Accepted Name:
Cyperus eragrostis Lam.
Publication: Tabl. Encycl. 1: 146. 1791. 1791.

Synonyms & Misapplications:
Cyperus vegetus Willd.
Additional Resources:

PNW Herbaria: Specimen records of Cyperus eragrostis in the Consortium of Pacific Northwest Herbaria database.

WA Flora Checklist: Cyperus eragrostis checklist entry.

E-Flora BC: Cyperus eragrostis atlas page.

CalPhotos: Cyperus eragrostis photos.

USDA Plants: Cyperus eragrostis information.

11 photographs:
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