Centaurea diffusa

Centaurea diffusa_diffuse knapweed_flowerheads_JM DiTomaso
Photo courtesy Joseph DiTomaso

Synonyms: Acosta diffusa (Lam.) Sojak

Common names: diffuse knapweed

Centaurea diffusa (diffuse knapweed) is usually a biennial plant (family Asteraceae) that forms dense infestations. Seeds disperse when stems break off and tumble in the wind. Diffuse knapweed is not very common in California, but is one of the most invasive species in many other western states.

Cal-IPC Rating: Moderate

Cal-IPC Assessment

Plant Assessment Form - Information gathered by Cal-IPC on the impacts, rate of spread, and distribution of invasive plants in California. Does not include management information.

Weed RIC Management Notes

  • Management Notes - Information on management techniques and effectiveness from the University of California Cooperative Extension’s Weed Research & Information Center.

Cal-IPC Newsletter Articles

Cal-IPC Symposium Presentations

Presentations are linked where available. Where a presentation is not available, find more information by reading the abstract in the Cal-IPC Symposia Archive.

There are no Symposium presentations associated with this species yet.

Other Centaurea diffusa Information

  • CalPhotos - Images of plants taken mostly in California.
  • Calflora - See the distribution of this species on Calflora's map of California.
  • CalWeedMapper - Distribution information with ability to determine regional priorities.
  • Jepson Online Interchange for California Flora - Information on taxonomy, biology, and distribution from UC Berkeley's Jepson Herbarium.
  • CDFA - California official noxious weeds.
  • USDA PLANTS Database - Federal database with information on identification and distribution, and links to websites in individual states.
  • Bugwood - National database from the Center for Invasive Species and Ecosystem Health at the University of Georgia.