Source: California Invasive Plant Council


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

Centaurea virgata (squarrose knapweed)

Centaurea virgata
Centaurea virgata
Photo courtesy Joseph DiTomaso

Centaurea virgata (squarrose knapweed) is a perennial (family Asteraceae) found in the Klamath and Cascade Ranges, Modoc Plateau and northern Sierra Nevada Mountains of California. Squarrose knapweed favors disturbed open sites, including degraded rangeland, logged areas, grasslands and roadsides. Squarrose knapweed seed dispersal is enhanced by soil and water movement, and by clinging to humans and animals. Seed dispersal and reproduction can be limited by mowing or mechanical removal of plants before seed-set. Squarrose knapweed is a listed noxious weed in several western states.

Cal-IPC Inventory rating: Moderate

Cal-IPC Resources on Centaurea virgata

Cal-IPC News Articles

  • Richardson, B. (2004). The A-rated north. Cal-IPC News. 12: 4-5,14.

Cal-IPC Symposium Proceedings

  • Bauder, E. T. (1996). Exotics in the southern California bernal pool ecosystem. California Exotic Pest Plant Council Symposium '96. San Diego, CA, CA.
  • Butler, E. and S. Britting (1998). Mapping and control of weeds in the American River Parkway. California Exotic Pest Plant Council Symposium '98. Ontario, CA.
  • Carrithers, V. F. (1997). Using Transline* herbicide to control invasive plants. California Exotic Pest Plant Council Symposium '97. Concord, CA.
  • DiTomaso, J. M. (1995). Overview of extension non-crop weed research in California. California Exotic Pest Plant Council Symposium '95. J. Lovich, J. Randall and M. Kelly. Pacific Grove, CA.
  • DiTomaso, J. M., C. Benefield, et al. (1998). Reproductive biology of yellow starthistle (Centaurea solstitialis) maximizing late season control. California Exotic Pest Plant Council Symposium '98. Ontario, CA..
  • DiTomaso, J. M., G. B. Kyser, et al. (1998). Prescribed burning for control of yellow starthistle (Centaurea solstitialis) and enhanced native plant diversity. California Exotic Pest Plant Council Symposium '98. Ontario, CA.
  • Rusmore, J. T. (1995). Use of fire and cutting to control yellow starthistle. California Exotic Pest Plant Council Symposium '95. M. Kelly and J. Lovich. Pacific Grove, CA.
  • Young, J. A., C. D. Clements, et al. (2000). Purple starthistle seed germination. California Exotic Pest Plant Council Symposium 2000. M. Kelly. Ontario, CA.

Other Resources on Centaurea virgata

  • USDA PLANTS database - Federal database with information on identification and distribution, and links to websites in individual states.
  • Jepson Online Interchange for California Flora - Information on taxonomy, biology, and distribution from the UC Berkeley Jepson Herbarium.
  • CalFlora - Distribution information by county based on submitted observations and herbarium specimens.
  • CalPhotos - Images of plants taken mostly in California.