Page authors: Don Knoke, David Giblin
Centaurea diffusa
diffuse knapweed, tumble knapweed, white knapweed

Distribution: Occurring on both sides of the Cascades crest in Washington; Yukon Territory to California, east across much of the U.S. and Canada to northeastern North America.

Habitat: Roadsides, fields, meadows, ditches, wastelots, and other disturbed, open areas; noxious.

Flowers: July-September

Origin: Introduced from the eastern Mediterranean region

Growth Duration: Annual, Perennial

Conservation Status: Not of concern


Diffusely branched annual or biennial 1-6 dm. tall.


Leaves small, more or less pinnatifid, the lower ones early deciduous, the reduced ones or the inflorescence mostly entire.


Heads numerous, narrow; involucre 8-10 mm. high, the middle and outer bracts coarsely comb-like and tipped with a slender spine 1.5-4 mm. long; flowers few, white or rose-purple, the marginal ones not enlarged; pappus wanting; receptacle densely bristly.

Accepted Name:
Centaurea diffusa Lam.
Publication: Encycl. 1: 675. 1785.

Synonyms & Misapplications:
(none provided)
Additional Resources:

PNW Herbaria: Specimen records of Centaurea diffusa in the Consortium of Pacific Northwest Herbaria database.

WA Flora Checklist: Centaurea diffusa checklist entry.

E-Flora BC: Centaurea diffusa atlas page.

CalPhotos: Centaurea diffusa photos.

USDA Plants: Centaurea diffusa information.

49 photographs:
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