Carduus tenuiflorus

Carduus tenuiflorus_slenderflower thistle_JM DiTomaso_cropped
Photo: Joseph DiTomaso

Common names: slenderflower thistle; Italian thistle; multiheaded thistle; seaside thistle; shore thistle; winged plumeless thistle

Carduus tenuiflorus (slenderflower thistle) is a tall annual or biennial  herb (family Asteraceae) that is native to Europe and is distributed across the California coast and in the Central Valley and Sierra foothill grasslands. It is similar in appearance and habit to Italian thistle (Carduus pycnocephalus), but is far less widely distributed and difficult to distinguish. Plants typically have more flower heads per cluster (5-20) and phyllaries (flower head scales) that are scarious-margins.  Slenderflower thistle reduces forage for wildlife and livestock due to its spiny nature.

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.

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

There are no newsletter articles associated with this species yet.

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.

There are no Symposium presentations associated with this species yet.

Other Carduus tenuiflorus 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 tenuiflorus_phyllaries_copyright_DeanKelch(CDFA)
    Carduus tenuiflorus (slenderflower thistle) phyllaries. Photo: &#169 Dean Kelch, CDFA
    Carduus tenuiflorus_flower heads_ZoyaAkulova
    Carduus tenuiflorus (slenderflower thistle) flower heads. Photo: Zoya Akulova
    Carduus tenuiflorus_stem_ZoyaAkulova
    Carduus tenuiflorus (slenderflower thistle) stem. Photo: Zoya Akulova
    Carduus tenuiflorus_growth habit_ZoyaAkulova
    Carduus tenuiflorus (slenderflower thistle) growth habit. Photo: Zoya Akulova