Page author: Don Knoke
Conyza canadensis
Canadian fleabane, horseweed
WTU specimens
Other herbaria

Distribution: Common introduction throughout the United States and Canada

Habitat: Weed of roadsides, dry or moist disturbed ground

Flowers: July - September

Origin: Native

Conservation Status: Not of concern


Annual or winter annual, usually nearly glabrous, 2-10 dm. tall, the stem erect, unbranched below.


Leaves numerous, narrow, the lower oblanceolate, petiolate, up to 10 cm. long and 1 cm. wide, often deciduous, the other leaves linear and sessile, somewhat hairy.


Heads numerous in an open inflorescence, small; involucre 3-4 mm. high, imbricate; disk flowers yellow, ray flowers white and very short, barely exceeding the pappus.


Achene flattened, about 2 mm. long with white, bristly pappus.

Accepted Name:
Conyza canadensis (L.) Cronquist
Publication: Bull. Torrey Bot. Club. 70: 632. 1943. 1943.

Synonyms & Misapplications:
Conyza canadensis (L.) Cronquist var. canadensis
Conyza canadensis (L.) Cronquist var. glabrata (A. Gray) Cronquist
Additional Resources:

PNW Herbaria: Specimen records of Conyza canadensis in the Consortium of Pacific Northwest Herbaria database.

WA Flora Checklist: Conyza canadensis checklist entry.

E-Flora BC: Conyza canadensis atlas page.

CalPhotos: Conyza canadensis photos.

USDA Plants: Conyza canadensis information.

18 photographs:
Group by