Source: California Invasive Plant Council


URL of this page: http://www.cal-ipc.org/ip/management/plant_profiles/Onopordum_acanthium.php

Onopordum acanthium (Scotch thistle)

Onopordum acanthium
Scotch thistle flower head and winged spiny stem
Photo courtesy Joseph DiTomaso

Onopordum acanthium (Scotch thistle) is a biennial or short-lived perennial (family Asteraceae) which is primarily found in the northeastern regions of California. Severe infestations can form tall, dense, impenetrable stands, especially in fertile soils. Onopordum acanthium reproduces only by seeds, which can germinate year round, and it is drought resistant. Infestations can reduce forage and impede movement for livestock and wildlife.

Cal-IPC Inventory rating: High

Cal-IPC Resources on Onopordum acanthium

Cal-IPC News Articles

  • Brusati, E., D. Morawitz, et al. (2011). Prioritizing Regional Response to Invasive Plants in the Sierra Nevada. Cal-IPC News. 19: 4, 5, 10.
  • Richardson, B. (2004). The A-rated north. Cal-IPC News. 12: 4-5,14.
  • Donaldson, S. (2003). Fighting weeds in the Tahoe basin. CalEPPC News. 11: 7.
  • Pitcairn, M. (2000). All weeds that have approved biological control agents, accidental introductions and others. CalEPPC News. 8.

Cal-IPC Symposium Proceedings

  • Leavitt, J. R. and C. Pirosko (2002). A brief overview of the California Dept. of Food and Agriculture’s A-rated noxious weed education and eradication program. California Exotic Pest Plant Council Symposium 2002. Sacramento, CA.
  • O'Connell, R. A. (1999). The state of California's noxious weed eradication programs. California Exotic Pest Plant Council. Sacramento, CA.
  • Carrithers, V. F. (1997). Using Transline* herbicide to control invasive plants. California Exotic Pest Plant Council Symposium '97. Concord, CA.
  • O'Connell, R. A. (1997). Hydrilla: A case study: The state of California's noxious weed eradication programs. California Exotic Pest Plant Council Symposium '97. Concord, CA.

Other Resources on Onopordum acanthium