Carduus pycnocephalus

Carduus pycnocephalus_Italian thistle_JM DiTomaso
Photo: 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?

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.

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 pycnocephalus Information

  • Bugwood - National database from the Center for Invasive Species and Ecosystem Health at the University of Georgia.
  • 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 pycnocephalus_seedlings_copyright_2019_NealKramer
    Carduus pycnocephalus (Italian thistle) seedlings. Photo: © 2019 Neal Kramer
    Carduus pycnocephalus_flower heads (senescent)_ZoyaAkulova
    Carduus pycnocephalus (Italian thistle) flower heads (senescent). Photo: Zoya Akulova
    Carduus pycnocephalus_seed and pappus_ZoyaAkulova
    Carduus pycnocephalus (Italian thistle) seed and pappus. Photo: Zoya Akulova
    Carduus pycnocephalus_flower heads_BobCase
    Carduus pycnocephalus (Italian thistle) flower heads. Photo: Bob Case
    Carduus pycnocephalus_stem_KeirMorse
    Carduus pycnocephalus (Italian thistle) stem. Photo: Keir Morse
    Carduus pycnocephalus_phyllaries_copyright2001_FredHrusa(CDFA)
    Carduus pycnocephalus (Italian thistle) phyllaries. Photo: © 2001 Fred Hrusa, CDFA