Centaurea melitensis

Centaurea melitensis_malta starthistle_JM DiTomaso
Photo courtesy Joseph DiTomaso

Common names: tocalote; Malta starthistle

Centaurea melitensis (Malta starthistle, tocalote) is a bushy annual (family Asteraceae) found throughout most of California and in many other western states. Malta starthistle prefers disturbed and open areas, including grasslands, open woodlands, agricultural fields and roadsides. It is most invasive in California’s central western and southwestern regions. While Malta starthistle is less invasive than yellow starthistle (Centaurea solstitialis), but it still spreads quickly by producing great quantities of seed if given the proper conditions. Insects such as the false peacock fly (Chaetorellia succinea) and hairy weevil (Eustenopus villosus) have been used as biological controls with some success.

Cal-IPC Rating: Moderate

CDFA Rating: C*

Cal-IPC Assessment

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 Centaurea melitensis Information

  • CalPhotos - Images of plants taken mostly in California.
  • Calflora - See the distribution of this species on Calflora's map of California.
  • CalWeedMapper - Distribution information with ability to determine regional priorities.
  • Jepson Online Interchange for California Flora - Information on taxonomy, biology, and distribution from UC Berkeley's Jepson Herbarium.
  • CDFA - California official noxious weeds.
  • USDA PLANTS Database - Federal database with information on identification and distribution, and links to websites in individual states.
  • EDDMapS - North American distribution based on Early Detection and Distribution Mapping System.