Carduus acanthoides

Carduus acanthoides_Plumeless Thistle__flower_JM DiTomaso
Photo courtesy Joseph DiTomaso

Synonyms: Carduus fortior

Common names: plumeless thistle; bristly thistle; giant plumeless thistle; spiny thistle

Carduus acanthoides (plumeless thistle) is a tall biennial (family Asteraceae) with spiny leaves that colonizes disturbed open sites, roadsides, pastures, annual grasslands, and waste areas. It can inhibit growth of native plants in its vicinity. Plumeless thistle is uncommon in California, and the California Department of Food and Agriculture has an active program to control known populations.

Cal-IPC Rating: Limited

Cal-IPC Assessment

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 RIC 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

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.

  • Aminopyralid: A new reduced risk active ingredient for control of broadleaf invasive and noxious weeds. Carrithers, Vanelle; Miller, Beau; Burch, Pat; Kline, Bill; Masters, Bob; Nelson, Jeff; Halstvedt, Mary; Troth, John; Breuninger, Jamie (2005)
  • The state of California’s noxious weed eradication programs. O'Connell, Ross A. (1999)
  • Weeding the wilderness: Non-native plant management at Point Reyes National Seashore. Cooper, V. Kimberly; Moritsch, Barbara J. (1999)
  • Hydrilla: A case study: The state of California’s noxious weed eradication programs. O'Connell, Ross A. (1997)

Other Carduus acanthoides Information

  • CalPhotos - Images of plants taken mostly in California.
  • Calflora - See the distribution of this species on Calflora's map of California.
  • CalWeedMapper - Distribution information with ability to determine regional priorities.
  • Jepson Online Interchange for California Flora - Information on taxonomy, biology, and distribution from UC Berkeley's Jepson Herbarium.
  • CDFA - California official noxious weeds.
  • USDA PLANTS Database - Federal database with information on identification and distribution, and links to websites in individual states.