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You are here: Home / Plants / Species Profiles / Diffuse Knapweed
Species Profiles

Diffuse Knapweed

Diffuse Knapweed

Scientific name: Centaurea diffusa Lam. (ITIS)

Synonym: Acosta diffusa (Lam.) (ITIS)

Common names: Diffuse knapweed, white knapweed, spreading knapweed, tumble knapweed

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Selected Resources

Native To: Eastern Mediterranean region (Wilson and Randall 2005)

Date of U.S. Introduction: 1800s (Wolfson et al. 2005)

Means of Introduction: Introduced accidentally through contaminated seed (Zouhar 2001)

Impact: Crowds out native species (Wilson and Randall 2005)

Current U.S. Distribution:


Selected Resources:

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Council or Task Force

Priority Species: Knapweed
Washington State Recreation and Conservation Office. Washington Invasive Species Council.

Fact Sheet: Diffuse Knapweed (Jan 2014; PDF | 650 KB)
Alberta Invasive Species Council (Canada).
See also: Fact Sheets for more information about individual invasive species, including those listed as "Prohibited Noxious" and "Noxious" under the Alberta Weed Control Act


Invasive Plant Atlas of the United States - Diffuse Knapweed
University of Georgia. Center for Invasive Species and Ecosystem Health.

Invasive Species Compendium - Centaurea diffusa
CAB International.

Plantwise Technical Factsheet - Diffuse Knapweed (Centaurea diffusa)
CABI. Plantwise Knowledge Bank.

Global Invasive Species Database - Centaurea diffusa (herb)
IUCN. Species Survival Commission. Invasive Species Specialist Group.

Federal Government

U.S. National Plant Germplasm System - Centaurea diffusa
USDA. ARS. National Genetic Resources Program. GRIN-Global.

Biology and Biological Control of Knapweed (Apr 2005, 3rd Ed; PDF | 2.85 MB)
USDA. FS. Forest Health Technology Enterprise Team.

Fire Effects Information System (FEIS) - Centaurea diffusa
USDA. FS. Rocky Mountain Research Station. Fire Sciences Laboratory.

PLANTS Database - Diffuse Knapweed
USDA. NRCS. National Plant Data Center.

State Government

Encycloweedia: Data Sheet - Centaurea genus
California Department of Food and Agriculture.
Included on California's noxious weed list; see Encycloweedia: Program Details for additional resources.

Noxious Weed Species - Diffuse Knapweed
Colorado Department of Agriculture. Conservation Services Division. Noxious Weed Program.

Diffuse Knapweed (Centaurea diffusa)
Wisconsin Department of Natural Resources.

Class B Noxious Weed: Diffuse Knapweed
Washington State Noxious Weed Control Board.

King County (Washington) Noxious Weed Control Program - Diffuse Knapweed
King County Department of Natural Resources (Washington). Water and Land Resources Division.


Weed Control in Natural Areas in the Western United States: Diffuse Knapweed (2013; PDF | 236 KB)
University of California. Weed Research and Information Center.

Diffuse and Spotted Knapweed
Colorado State University. Cooperative Extension.

Spotted and Diffuse Knapweed - Noxious Weeds of Nebraska (PDF | 1.11 MB)
University of Nebraska - Lincoln. Cooperative Extension.

Know Your Knapweeds
North Dakota State University. Extension Service.


Noxious Weed Information - Diffuse Knapweed (B List)
Colorado Weed Management Association.

Weed Identification - Diffuse Knapweed
Montana Weed Control Association.


Integrated Taxonomic Information System. Centaurea diffusa. [Accessed Sep 10, 2014].

Wilson, L.M. and C.B. Randall. 2005. Biology and biological control of knapweed (PDF | 2.96 MB) (FHTET-2001-07) Morgantown, West Virginia: U.S. Forest Service Forest Health Technology Enterprise Team.

Wolfson, B.A., T.E. Kolb, C.H. Sieg, and K.M. Clancy. 2005. Effects of post-fire conditions on germination and seedling success of diffuse knapweed in northern Arizona. Forest Ecology and Management 216(1-3):342-358.

Zouhar, K. 2001. Centaurea diffusa. In: Fire Effects Information System. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory.

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Last Modified: Sep 29, 2016
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