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Species
Information
- bull
thistle
- Cirsium
vulgare (Savi) Ten.
- USDA
Symbol: CIVU
- Oregon
Noxious Weed Designation: B
- Pictures
Identification:
Biennial; blooms July to September. Grows 2 to 5 ft tall. Many branches sporting green to brown spines and hairs. Leaves pinnately lobed, hairy, prickly on the upper side and cottony underneath. Flowers 1 1/2 to 2 in wide and clustered at ends of branches. Flowers dark purple. Seeds topped by a circle of plume-like white hairs.
Impacts: Bull thistle is a very transitory weed and often shows up in large numbers in newly disturbed ground. It is most commonly found in pastures, rangeland, newly logged sites, and displaces forbs and grasses. Biocontrol and good pasture management will maintain this species as merely a nuisance and not a significant economic threat.
Biological
Controls: Four approved biocontrol agents, a seed head gall fly, a crown weevil, a seed head weevil and a flower fly are established in Oregon.
Oregon
Maps of Bull Thistle Distribution
Links:
USDA
Plants Database information on bull thistle
GRIN
Database information on bull thistle
Oregon Department
of Agriculture information on bull thistle
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