Page authors: Don Knoke, David Giblin
Ageratina occidentalis
western boneset, western snakeroot

Distribution: Occurring east of the Cascades crest in Washington; Washington to California, east to Montana, Utah, and Nevada.

Habitat: Rocky places at various altitudes.

Flowers: June-August

Origin: Native

Growth Duration: Perennial

Conservation Status: Not of concern

Pollination: Bees, flies, beetles, wasps


Rhizomatous perennial from a woody base, the several stems 1.5-7 dm. tall.


Leaves alternate or a few opposite, petiolate, narrowly to broadly deltoid or deltoid-ovate, 1.5-6.5 cm. long, more or less toothed, glandular on the lower side.


Heads small, clustered at the ends of the stems and branches; involucre 3-6 mm. high, the bracts about equal; flowers all tubular and perfect, the corollas pink to red-violet, 9-21 in each head; style branches club-shaped; pappus of capillary bristles; receptacle naked.


Achenes 5-angled, glandular.

Accepted Name:
Ageratina occidentalis (Hook.) R.M. King & H. Rob.
Publication: Phytologia. 19: 224. 1970.

Synonyms & Misapplications:
Eupatorium occidentale Hook. [HC]
Additional Resources:

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

WA Flora Checklist: Ageratina occidentalis checklist entry.

OregonFlora: Ageratina occidentalis information.

E-Flora BC: Ageratina occidentalis atlas page.

CalPhotos: Ageratina occidentalis photos.

USDA Plants: Ageratina occidentalis information.

18 photographs:
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