Plumeless Thistle
Carduus acanthoides
Washington State Classification
Class B — Control Required (Designated)
Plumeless thistle invades pastures, meadows, and fields crowding out desirable forage plants.
Required control in Region 1 (all western Washington counties)
Quick Reference
Identification
Growth Habit
It is an upright, spiny, biennial growing up to 8 feet tall.
Leaves
Dark green leaves are deeply lobed to compound with hair on the undersides and spines along the leaf margins.
Flowers
Flowers are solitary or in clusters of 2 to 3 flower heads with reddish purple flowers.
Fruit & Seeds
Seeds (achenes) are smooth and hairless.
Impact
Plumeless thistle invades pastures, meadows, and fields crowding out desirable forage plants. Livestock will not graze in areas heavily infested with plumeless thistle.
Ecology & Spread
Habitat
Plumeless thistle grows in pastures, stream valleys, fields and roadsides. Please click here to see a county level distribution map of plumeless thistle in Washington.
Spread Mechanisms
Reproduction
Plumeless thistle reproduces by seed.
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Control Methods
Mechanical
- Plumeless thistle can be dug or grubbed out.