Washingtonia robusta
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. It is native to semi-arid landscapes of northwestern Mexico, including Baja California. Mexican fan palm is a common landscape ornamental that has become invasive in riparian areas, orchards and landscaped areas. It is superficially very similar and hybridizes with California fan palm (Washingtonia filifera). It can be distinguished by its more slender trunk, more compact head of leaves, bright green leaf color, and a more red-brownish (versus gray) trunk color. 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 relatively easily by pulling seedlings, cutting trunks below their growing point, and with drill-and-fill trunk application of herbicide.
Cal-IPC Rating: Moderate — Alert?CDFA Rating: None?
Assessment(s)
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
- Lessons learned from a 12-year eradication program targeting 34 species. Knapp, John. Vol 27, Issue 1
- Which weeds dominate southern California urban riparian systems?. Burkhart, Brad; Kelly, Mike. Vol 13, Issue 1
- Education: Wildland weed tours and talks. Kelly, Mike. Vol 08, Issue 1
- Roundup of Arundo projects reveals commitment, strategic weakness. Kelly, Mike. Vol 07, Issue 2
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.
- 2002 Red alert! New introductions and recent expansions in California. Tu, Mandy; Randall, John M. (2002)
Other Washingtonia robusta 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
