Washingtonia robusta

Washingtonia robusta_Mexican fan palm_JM DiTomaso
Photo courtesy Joseph DiTomaso

Synonyms: W. filamentosa (often mistaken for native W. filifera)

Common names: Mexican fan palm; Washington palm; skyduster; thread palm

Washingtonia robusta (Mexican fan palm) is a single-trunked palm tree (family Arecaceae) found in the San Francisco Bay area, southern Sacramento Valley and on California’s south coast. Mexican fan palm is a common landscape ornamental that has become invasive in riparian areas, orchards and landscaped areas. This palm is known to create monospecific stands in riparian areas, and dead fronds of the tree can create a fire hazard. The species can be controlled with relative ease by removing the seedlings.

Rating: Moderate

Cal-IPC Resources

  • 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.
  • CalWeedMapper - Statewide maps, climate models, and reports.
  • Cal-IPC News - Our quarterly newsletter. Each issue is available as a pdf.
  • Cal-IPC Symposium Proceedings - Presentations and papers from our annual Symposium.
  • Don't Plant a Pest! - Select your region to find non-invasive alternatives to ornamental species. Also see our statewide brochure on trees.

    Other Resources

    • 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.

    Symposium Presentations

    • Kelly, M., B. Peterson, et al. (2007). Drilling and injecting two invasive palm species. California Invasive Plant Council Symposium 2007. San Diego, CA, California Invasive Plant Council.
    • Burkhart, B. and M. Kelly (2007). How to develop user-friendly riparian corridor invasive exotic species/habitat restoration master plans: Experiences on the San Diego and Otay Rivers. California Invasive Plant Council Symposium 2007. San Diego, CA, California Invasive Plant Council.
    • Kelly, M. (2001). Drilling as a technique for controlling eucalyptus, palms & other exotic trees. California Exotic Pest Plant Council Symposium 2001. San Diego, CA.
    • Tu, M. and J. M. Randall (2002). 2002 Red alert! New introductions and recent expansions in California. California Exotic Pest Plant Council Symposium 2002. Sacramento, CA.
    • Tu, M. and J. M. Randall (2003). 2003 Cal-IPC red alert! New invasions, recent expansions, and a few others to be on the look-out For. California Invasive Plant Council Symposium 2003. Kings Beach, CA.

    Cal-IPC News Articles

    • Burkhart, B. and M. Kelly (2005). Which weeds dominate southern California urban riparian systems? Cal-IPC News. 13: 4-5,12.
    • Kelly, M. (1999). Roundup of Arundo projects reveals commitment, strategic weakness. CalEPPC News. 7: 4-9.
    • Kelly, M. (2000). Education: Wildland weed tours and talks. CalEPPC News. 8: 3-4.
    • Tu, M. and J. M. Randall (2002). 2002 Red Alert! New introductions and recent expansions in California.
    • Tu, M. and J. M. Randall (2003). 2002 REd Alert! New introductions and recent expansions in California.