Carduus acanthoides

Carduus acanthoides_Plumeless Thistle__flower_JM DiTomaso
Photo: 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?

CDFA Rating: -*?


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

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.

Other Carduus acanthoides 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

    Carduus acanthoides_growth habit_Douglas Barbe, CDFA_cropped
    Carduus acanthoides (plumeless thistle) growth habit. Photo: Douglas Barbe, CDFA
    Carduus acanthoides_leaves and root_DFoley, CDFA_cropped
    Carduus acanthoides (plumeless thistle) leaves and root. Photo: DFoley, CDFA