California Invasive Plant Council

Cirsium vulgare

Synonyms: Carduus lanceolatus, Cirsium lanceolatum

Common names: bull thistle

Cirsium vulgare (bull thistle) is a perennial or biennial forb (family Asteraceae) Bull thistle is widespread in California and is most common in coastal grasslands, along edges of fresh and brackish marshes, and in meadows and mesic forest openings in the mountains below 7,000 feet (2,120 m). It is most troublesome in recently or repeatedly disturbed areas such as pastures, overgrazed rangelands, recently burned forests and forest clearcuts, and along roads, ditches, and fences. Besides out-competing native plant species for water, nutrients, and space, the presence of bull thistle in hay decreases feeding value and lowers market price.

Cal-IPC Rating: Moderate?

Explanation of Cal-IPC ratings

• High – These species have severe ecological impacts on physical processes, plant and animal communities, and vegetation structure. Their reproductive biology and other attributes are conducive to moderate to high rates of dispersal and establishment. Most are widely distributed ecologically.
• Moderate – These species have substantial and apparent-but generally not severe-ecological impacts on physical processes, plant and animal communities, and vegetation structure. Their reproductive biology and other attributes are conducive to moderate to high rates of dispersal, though establishment is generally dependent upon ecological disturbance. Ecological amplitude and distribution may range from limited to widespread.
• Limited – These species are invasive but their ecological impacts are minor on a statewide level or there was not enough information to justify a higher score. Their reproductive biology and other attributes result in low to moderate rates of invasiveness. Ecological amplitude and distribution are generally limited, but these species may be locally persistent and problematic.
• Alert – An Alert is listed on species with High or Moderate impacts that have limited distribution in California, but may have the potential to spread much further.
• Watch – These species have been assessed as posing a high risk of becoming invasive in the future in California.

CDFA Rating: -*?

Explanation of CDFA ratings

• A – A pest of known economic or environmental detriment and is either not known to be established in California or it is present in a limited distribution that allows for the possibility of eradication or successful containment.
• B – A pest of known economic or environmental detriment and, if present in California, it is of limited distribution.
• C – A pest of known economic or environmental detriment and, if present in California, it is usually widespread.
• D – An organism known to be of little or no economic or environmental detriment, to have an extremely low likelihood of weediness, or is known to be a parasite or predator.
• Q – An organism or disorder suspected to be of economic or environmental detriment, but whose status is uncertain because of incomplete identification or inadequate information.
• * – An asterisk next to the rating indicates that a plant is included in the CCR Section 4500 list of California State Noxious Weeds.
• -* – This plant is included in the CCR Section 4500 list of California State Noxious Weeds, but is otherwise not rated.

More details

Assessment(s)

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.

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
• Spring Campaign for Climate Adaptation a success!. Cal-IPC. Vol 21, Issue 2
• From Bull thistle in Yosemite to ants on islands: An interview with Cal-IPC’s first president, John Randall. Darin, Gina. Vol 19, Issue 1
• Feed the birds, but don’t spread weeds. America, Weed Science Society of. Vol 17, Issue 2
• Don’t sell a pest: A new partnership to prevent plant invasions through horticulture. Connick, Sarah; Gerel, Mike. Vol 13, Issue 2
• Fighting weeds in the Tahoe basin. Donaldson, Sue. Vol 11, Issue 2
• California Exotic Pest Plant Council draft list exotic plants of greatest concern October 1993. CalEPPC. Vol 01, Issue 4
• Control of exotic plants in an herbaceous understory. Perala, Christine; Hoover, Doris A.; Parra-Szijj, E.A.. Vol 01, Issue 3

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.

• Tackling invasive plants after the 2020 Angeles National Forest fire season. Castro, Andrew (2022)
• Interactions among insects and weeds in western U.S. forests. Fettig, Christopher; Runyon, Justin; Trilling, Jared; Mortenson, Leif; Audley, Jackson (2020)
• The role of public gardens as sentinels of plant invasion. Culley, Theresa; Dreisilker, Kurt; Ryan, Clair; Landel, Hans; Cavallin, Nadia; Arcate Schuler, Jessica; Shultz, Brittany; Gettig, Roger; Havens, Kayri (2020)
• Fire working group. Clines, Joanna; DiTomaso, Joe; Goode, Suzanne (2004)
• Forbs working group. Pirosko, Carri; Schoenig, Steve (2004)
• Partnering to prevent invasions of plants of horticultural origin. Connick, Sarah; Gerel, Mike (2004)
• A decade of dune restoration at the Lanphere Dunes. Pickart, Andrea (2003)
• Getting the job done: Working within the regulatory environment at Lake Tahoe to manage weeds. Donaldson, Susan; West, Wendy; Taylor, Kirk (2003)
• Using Transline* herbicide to control invasive plants. Carrithers, Vanelle F. (1997)

Other Cirsium vulgare 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.

Additional photos