Carduus pycnocephalus

Carduus pycnocephalus_Italian thistle_JM DiTomaso
Photo courtesy Joseph DiTomaso

Common names: Italian thistle

Carduus pycnocephalus (Italian thistle) is a winter annual forb (family Asteraceae) widely distributed in disturbed open sites, roadsides, pastures, annual grasslands, and waste areas in much of California.

Cal-IPC Rating: Moderate

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.

Cal-IPC Newsletter Articles

Cal-IPC Symposium Presentations

  • Archbald, G. (1998). Mechanical control methods: beyond weed bashing. California Exotic Pest Plant Council Symposium '98. Ontario, CA.
  • Boyd, D. (1997). Eucapyptus removal on Angel Island. California Exotic Pest Plant Council Symposium '97. Concord, CA.
  • Briscoe, E. and T. Anderson (2000). War on weeds - invasive weed education and outreach program. California Exotic Pest Plant Council Symposium 2000. Concord, CA.
  • Clines, J., J. DiTomaso, et al. (2004). Fire working group. California Invasive Plant Council Symposium 2004. Ventura, CA.
  • Guerriero, A. (2002). Monitoring Carduus pycnocephalus (Italian thistle) on grasslands in coastal central California. California Exotic Pest Plant Council Symposium 2002. Sacramento, CA.
  • Pirosko, C. and S. Schoenig (2004). Forbs working group. California Invasive Plant Council Symposium 2004. Ventura, CA.
  • Pitcairn, M. J. and D. M. Woods (1998). Control methods: Biological control. California Exotic Pest Plant Council Symposium '98. Ontario, CA.
  • Pitcairn, M. J. and D. M. Woods (1998). Control methods: biological control. California Exotic Pest Plant Council Symposium 1998. Ontario, CA.

Other Carduus pycnocephalus Information

  • CalPhotos - Images of plants taken mostly in California.
  • CalFlora - Distribution information based on submitted observations and herbarium specimens.
  • 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.
  • Bugwood - National database from the Center for Invasive Species and Ecosystem Health at the University of Georgia.