Washingtonia robusta H.Wendl., Arecaceae

Click on an image for links to BIGGER PICTURES

Present on Pacific Islands?  no

Primarily a threat at high elevations?  no

Risk assessment results: 

High risk, score: 15 (go to the risk assessment (Pacific))
Reject, score: 10 (go to the risk assessment (U.S. (Florida)))

Common name(s): [more details]

English: Mexican fan palm, Mexican Washington palm, Mexican washingtonia, skyduster palm, thread palm, Washington palm

French: palmier évantail du Mexique

Habit:  tree

Description:  "Flowers and fruits very similar to Washingtonia filifera, but differing in the following particulars:  Trunk: Brownish instead of grayish.  Rings more conspicuous, less vertical chinks.  Grows to greater height—to 80 ft.  More slender, except at expanded base.  If shag is removed, adhering leafbases form criss-cross pattern, similar to the palmettos.  Petiole: Reddish-brown, instead of green; conspicuously brown at base.  Usually more toothed than Washingtonia filifera, in young trees; less toothed in mature trees.  Not as long, to 4 ft.  Leaf: Bright-green, and usually not as wide as in Washington filifera.  Many long threads only in youth, disappearing with age.  Segments: Bright-green, instead of gray-green" (McCurrach, 1960; pp. 264-265).

Key to species of Washingtonia (from Oppenheimer & Bartlett, 2002; p. 3):
Trunk slender, tapered from a stout base; leaf blades bright green, hastula tawny beneath:  Washingtonia robusta.
Trunk stout without a broader base; leaf blades gray-green, lacking a tawny patch beneath the hastula:  Washingtonia filifera.

Habitat/ecology:  "Native to desert washes where underground water is continuously available, naturalized in disturbed areas with moderate rainfall" (Flora of North America online).

Propagation:  Seed

Native range:  Northwest Mexico (McCarrach, 1960; pp. 264-265).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Cook Islands Cook Islands	Cook Islands	cultivated	McCormack, Gerald (2011)
Ecuador (Galápagos Islands) San Cristóbal Group	San Cristóbal Island	introduced cultivated	Charles Darwin Foundation (2008)
Ecuador (Galápagos Islands) Santa Cruz Group	Santa Cruz Island	introduced cultivated	Charles Darwin Foundation (2008)
Guam Guam Island	Guam Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1987) (p. 89)
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive	Oppenheimer, Hank L./Bartlett, Randal T. (2002) (p. 3) West Maui. Voucher cited: Oppenheimer H79808 (BISH)
State of Hawaii Hawaiian Islands	O‘ahu Island	introduced invasive cultivated	Frohlich, Danielle/Lau, Alex (2010) (p. 5) Voucher cited: D. Frohlich & A. Lau 2008072303 (BISH)
New Caledonia New Caledonia Archipelago	Île Grande Terre	introduced cultivated	MacKee, H. S. (1994) (p. 112)

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
China China	Hong Kong	introduced cultivated	Wu, Te-lin (2001) (p. 296) Ornamental.
Mexico Mexico	Mexico (United Mexican States)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Singapore Singapore	Singapore (Republic of)	introduced cultivated	Chong, Kwek Yan/Tan, Hugh T. W./Corlett, Richard T. (2009) (p. 90) Cultivated only
United States (west coast) United States (west coast states)	USA (California)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2011)
United States (west coast) United States (west coast states)	USA (California)	introduced	U.S. Dept. Agr., Agr. Res. Serv. (2011) Naturalized

Indian Ocean
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
La Réunion (France) La Réunion Island	La Réunion Island	introduced invasive	Meyer, Jean-Yves/Lavergne, Christophe/Hodel, Donald R. (2008) (p. 76) Locally naturalized.
Mauritius Mautitius Islands (Mauritius and Rodrigues)	Mauritius Island	introduced cultivated	Meyer, Jean-Yves/Lavergne, Christophe/Hodel, Donald R. (2008) (p. 76)

Also reported from
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
United States (continental except west coast) United States (other states)	USA (Florida)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2011)
United States (continental except west coast) United States (other states)	USA (Florida)	introduced invasive	Meyer, Jean-Yves/Lavergne, Christophe/Hodel, Donald R. (2008) (p. 72)

Additional information:
Report (PDF format) from US Geological Survey, Biological Resources Division, Haleakala Field Station, Hawaii "Plants of Hawaii".
Fact sheet from Floridata.

Additional online information about Washingtonia robusta is available from the Hawaiian Ecosystems at Risk project (HEAR).

Information about Washingtonia robusta as a weed (worldwide references) may be available from the Global Compendium of Weeds (GCW).

Taxonomic information about Washingtonia robusta may be available from the Germplasm Resources Information Network (GRIN).

References:

Charles Darwin Foundation. 2008. Database inventory of introduced plant species in the rural and urban zones of Galapagos. Charles Darwin Foundation, Galapagos, Ecuador.

Charles Darwin Research Station. 2005. CDRS Herbarium records.

Chong, Kwek Yan/Tan, Hugh T. W./Corlett, Richard T. 2009. A checklist of the total vascular plant flora of Singapore: native, naturalised and cultivated species. Raffles Museum of Biodiversity Research, National University of Singapore. 273 pp.

Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce. 1987. A geographical checklist of the Micronesian monocotyledonae. Micronesica 20:1-126.

Frohlich, Danielle/Lau, Alex. 2010. New plant records from O‘ahu for 2008. In: Evenhuis, Neal L. and Eldredge, Lucias G., eds. Records of the Hawaii Biological Survey for 2008. Bishop Museum Occasional Papers 107:3-18.

Hunsberger, A. G. B. 2001. Invasive and banned plants of Miami-Dade County. U. of Fl. Extension. 3 pp.

MacKee, H. S. 1994. Catalogue des plantes introduites et cultivées en Nouvelle-Calédonie. Muséum National d'Histoire Naturelle, Paris, 164 p.

McCormack, Gerald. 2011. Cook Islands Biodiversity Database, Version 2007.2. Cook Islands Natural Heritage Trust, Rarotonga.

McCurrach, J. C. 1960. Palms of the world. Harper, New York.

Meyer, Jean-Yves/Lavergne, Christophe/Hodel, Donald R. 2008. Time Bombs in Gardens: Invasive Ornamental Palms in Tropical Islands, with Emphasis on French Polynesia (Pacific Ocean) and the Mascarenes (Indian Ocean). Palms; Journal of the International Palm Society 52: 23-35. .

Oppenheimer, Hank L./Bartlett, Randal T. 2002. New plant records from the main Hawaiian Islands. In: Evenhuis, Neal L. and Eldredge, Lucius G., eds. Records of the Hawaii Biological Survey for 2000. Part 2: Notes. Bishop Museum Occasional Papers. 69:1-14.

U.S. Dept. Agr., Agr. Res. Serv. 2011. National Genetic Resources Program. Germplasm Resources Information Network (GRIN). Online searchable database.

U.S. Dept. Agr., Nat. Res. Cons. Serv. 2011. The PLANTS Database. National Plant Data Center, Baton Rouge, LA 70874-4490 USA.

Wu, Te-lin. 2001. Check List of Hong Kong Plants. Hong Kong Herbarium and the South China Institute of Botany. Agriculture, Fisheries and Conservation Department Bulletin 1 (revised). 384 pp.