Rhaponticum repens

Acroptilon repens_Russian knapweed_JM DiTomaso
Photo: David Chang

Synonyms: Acroptilon repens, Centaurea repens

Common names: Russian knapweed, hardheads, creeping knapweed, mountain bluet, Turkestan thistle

Rhaponticum repens (Russian knapweed) is a perennial forb (family Asteraceae) found in isolated patches throughout California. It may have allelopathic properties. This plant is toxic to horses and crowds out native species.

Cal-IPC Rating: Moderate?

CDFA Rating: B*?


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 Rhaponticum repens 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

    Acroptilon repens_Russian knapweed_Bob Case_cropped
    Rhaponticum repens (Russian knapweed) rosette. Photo: Bob Case
    Rhaponticum repens_leaves and stem_copyright2021_NealKramer
    Rhaponticum repens (Russian knapweed) leaves and stem. Photo: &#169 2021 Neal Kramer
    Rhaponticum repens_seed (achene)_copyright2021_NealKramer
    Rhaponticum repens (Russian knapweed) seed (achene). Photo: &#169 2021 Neal Kramer
    Rhaponticum repens_flower head_RichardSpellenberg
    Rhaponticum repens (Russian knapweed) flower head. Photo: Richard Spellenberg
    Rhaponticum repens_growth habit_RichardSpellenberg
    Rhaponticum repens (Russian knapweed) growth habit. Photo: Richard Spellenberg