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USDA Symbol: CALA20
ODA rating: A and T
Woolly distaff thistle risk assessment
Noxious weed listing process
Distribution
Oregon wolly distaff thistle distribution
Click on image to view larger photo.
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Images courtesy of Ken French, Oregon Dept. of Agriculture.
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If images are downloaded and used from the ODA web site please be sure to credit the photographer.
Description
Annual; flowers July through August. Grows, up to 3 1/2’ tall. Alternate leaves, with long, stout marginal and terminal spines on the leaves. Flowers yellow in spiny heads. Very similar to smooth distaff thistle, except it has a longer pappas, is more densely covered in hairs, and seedling leaves are less deeply lobed.
Impacts
Carthamus species are believed to be the most serious threat to range and pasture lands in Oregon. Dense stands can crowd out other vegetation, livestock and recreational access. Dead plants remain standing, thorned and rigid for at least one year after dieing back. Woolly distaff thistle is not grazed as it is not palatable to domestic animals or wildlife. Once established, it is difficult to eliminate because of a persistant seedbank.
Introduction
Native to the Mediterranean region of Europe and central Europe. A very aggressive weed in California and known to occur in scattered locations in southwestern Oregon.
Distribution in Oregon
 
Biological controls
Biological control agents are not used on "A" listed weeds in Oregon. This weed is being managed for eradication.
Informational links
Wooly distaff thistle printable trifold(pdf)
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