squarrose knapweed

Asterales > Asteraceae > Centaurea virgata Lam.

Squarrose knapweed is a perennial forb that can grow 12-18 in. (30.5-45.7 cm) tall. The leaves are alternate and deeply dissected. Flowering occurs in early to mid-summer, when pink flowers develop in heads at the tips of the branches. This species is sometimes confused with diffuse knapweed (Centaurea diffusa), but can be distinguished from diffuse knapweed by the floral bracts. Bracts on squarrose knapweed are curved outward and are not laterally toothed. Squarrose knapweed is native to the Mediterranean region and occurs in open disturbed sites, such as rangelands, roadsides, and grasslands.


Identification, Biology, Control and Management Resources


Selected Images from Invasive.org

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Plant(s); post-fire emergence
Steve Dewey, Utah State University, Bugwood.org
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Plant(s); in flower
Steve Dewey, Utah State University, Bugwood.org
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Flower(s);
Steve Dewey, Utah State University, Bugwood.org
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Flower(s);
Steve Dewey, Utah State University, Bugwood.org
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Flower(s); seedhead
Cindy Roche, , Bugwood.org
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Infestation;
Steve Dewey, Utah State University, Bugwood.org
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Plant(s);
USDA ARS Archive, USDA Agricultural Research Service, Bugwood.org
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Plant(s);
USDA ARS Archive, USDA Agricultural Research Service, Bugwood.org
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Plant(s); from the eastern Mediterranean region is spreading on rangelands in the western United States.
Steve Dewey, Utah State University, Bugwood.org
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Infestation;
Sara Rosenthal, USDA Agricultural Research Service, Bugwood.org
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Infestation;
Steve Dewey, Utah State University, Bugwood.org
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Control; Spraying after fire
Steve Dewey, Utah State University, Bugwood.org
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Invasive Reference(s):

Check Invasive.org for most current lists.
  • Arizona - Noxious Weed Law
  • California - Noxious Weed Law
  • Colorado - Noxious Weed Law
  • Nevada - Noxious Weed Law
  • Oregon - Noxious Weed Law
  • Utah - Noxious Weed Law


External Links


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USDA Forest Service Bugwood University of Georgia