California Invasive Plant Council

Centaurea calcitrapa

Common names: purple starthistle

Centaurea calcitrapa (purple starthistle) grows as an annual, biennial or perennial (family Asteraceae) in fields, roadsides, disturbed open sites, grasslands, overgrazed rangelands, and logged areas in the northern and central coast ranges of California. It is native to Europe, and, like other Centaurea species, may produce allelopathic effects. It is highly competitive with other plants, often displacing desired vegetation.

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.

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

• One Tam unites around Marin’s mountain. Kesel, Rachel. Vol 24, Issue 3
• Eradication in the central Sierra. Cal-IPC. Vol 24, Issue 1
• Progress in the Sierra and beyond. Cal-IPC. Vol 22, Issue 1
• Weed biological control agents approved for California. Pitcairn, Michael J.; Smith, Lincoln; Moran, Patrick. Vol 22, Issue 1
• Tracking eradication progress . Guise, Vince. Vol 21, Issue 3
• Results of the CalEPPC questionnaire at Symposium ’98 in Ontario. DiTomaso, Joe. Vol 06, Issue 4
• California Exotic Pest Plant Council draft list exotic plants of greatest concern October 1993. CalEPPC. Vol 01, Issue 4

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.

• Early detection and rapid response: effective weed control at the landscape level. Farrell, Sharon; Patterson, Jesse; Kesel, Rachel; Brigham, Christy; Gregory, Nathan; Gardner, Leah (2020)

Other Centaurea calcitrapa 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