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purple starthistle (Centaurea calcitrapa)
PLEASE CALL 1-866-INVADER IF YOU SUSPECT YOU HAVE FOUND THIS SPECIES
 
ODA rating: A and T
 
USDA Symbol: CECA2
Oregon purple starthistle distribution
 
Other common names
red starthistle
 
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Images courtesy of Tom Forney, Oregon Dept. of Agriculture

 
If images are downloaded and used from the ODA web site please be sure to credit the photographer. 
 
Description
Annual or biennial; rosette forms in May and June, blooms midsummer through fall. Grows 1 to 6 feet tall. Plant covered in fine hairs. Leaves divided into narrow linear segments. Rosettes have spines in center. Flower heads are purple with straw-colored spine-like bracts over 1 inch in length. Seeds are not plumed, the distinguishing factor between this plant and Iberian starthistle.
 
Impacts
Closely resembles Iberian starthistle and both species have the ability to adapt to a variety of climactic conditions. They are extremely competitive along roadsides and in low-rainfall range situations as well as in higher rainfall pastures where they displace valuable forage species. The sharp spines deter grazing animals, access to livestock and wildlife, reduce the value of hay and can impede recreational use. This weedy plant has the potential to become widely established, having significant impact to agriculture and wildland resources.
 
Distribution in Oregon

Biological controls
Biological control agents are not used on "A" listed weeds in Oregon. This weed is being managed for eradication or containment.
 
Informational links
Printable purple starthistle trifold brochure (pdf)