Common names: Scotch thistle; cotton thistle; woolly thistle; winged thistle; jackass thistle; heraldic thistle
Onopordum acanthium (Scotch thistle) is a biennial or short-lived perennial (family Asteraceae) which is primarily found in the northeastern regions of California. Severe infestations can form tall, dense, impenetrable stands, especially in fertile soils. Onopordum acanthium reproduces only by seeds, which can germinate year round, and it is drought resistant. Infestations can reduce forage and impede movement for livestock and wildlife.Cal-IPC Rating: High?
CDFA Rating: A*?
Plant Assessment Form - Information gathered by Cal-IPC on the impacts, rate of spread, and distribution of invasive plants in California. Does not include management information.
Species ID Card
Invasive Species ID Card - To support field identification of early detection species, Cal-IPC has designed a set of Species ID cards that can be downloaded, printed double-sided, and trimmed to size.
Weed Management Notes
- Management Notes - Information on management techniques and effectiveness from the University of California Cooperative Extension’s Weed Research & Information Center.
Cal-IPC Newsletter Articles
- Weeds and climate resilience in Sierra meadows. Brusati, Elizabeth; Johnson, Doug. Vol 24, Issue 1
- Weed biological control agents approved for California. Pitcairn, Michael J.; Smith, Lincoln; Moran, Patrick. Vol 22, Issue 1
- Prioritizing Regional Response to Invasive Plants in the Sierra Nevada. Brusati, Elizabeth; Morawitz, Dana; Powell, Cynthia. Vol 19, Issue 2
- Fighting weeds in the Tahoe basin. Donaldson, Sue. Vol 11, Issue 2
Cal-IPC Symposium Presentations
Presentations are linked where available. Where a presentation is not available, find more information by reading the abstract in the Cal-IPC Symposia Archive.
There are no Symposium presentations associated with this species yet.
Other Onopordum acanthium Information
- CalPhotos - Images of plants taken mostly in California.
- Calflora - Distribution map and records of this species in California.
- CalWeedMapper - Distribution map of this species in California with ability to determine regional priorities.
- EDDMapS - Distribution of this species in North America.
- Jepson Interchange - Information on this plant's taxonomy, biology, and distribution from UC Berkeley's Jepson Herbarium.
- USDA PLANTS Database - Information on identification and distribution, with links to websites in individual states.