|Washingtonia filifera in native grove near Twentynine Palms, California.|
Washingtonia filifera (common name desert fan) is a species of flowering plant in the palm family (Arecaceae), native to southwestern North America. Growing to 15–20 m (49–66 ft) tall by 3–6 m (10–20 ft) broad, it is technically an evergreen monocot (not actually a tree) but 'tree-like' since it presents with a sturdy columnar trunk. It has waxy fan-shaped leaves which are described botanically as palmate.
Other common names include desert fan palm, California palm, fanpalm, petticoat palm, cotton palm, Arizona fan palm. The specific epithet filifera means "thread-bearing".
Washingtonia filifera is the only palm native to the Western United States, and the country's largest native palm (though most palms in Los Angeles and San Diego are specimens of the closely related and very similar W. robusta).
The primary populations are found in desert riparian habitats at spring-fed oases in the Colorado Desert (Low Desert) and throughout a major portion of the Mojave Desert. It is also found near watercourses in the Sonoran Desert along the Gila River in Yuma, along the Hassayampa River and near New River in Maricopa County, and in portions of Pima County, Pinal County, Mohave County (along the Colorado River) and several other isolated locations in Clark County, Nevada. It is also introduced in northern Baja California. It is a naturalized species in the warm springs near Death Valley and in the extreme northwest of Sonora (Mexico). It is also reportedly naturalized in Florida, Hawaii, the U.S. Virgin Islands, and Australia (New South Wales).
|This section needs additional citations for verification. (June 2014)|
Washingtonia filifera grows to 18 metres (59 ft) in height (occasionally to 25 metres (82 ft)) in ideal conditions.
The fronds are up to 3.5–4 metres (11–13 ft) long, made up of a petiole up to 2 metres (6.6 ft) long, bearing a fan of leaflets 1.5–2 metres (4.9–6.6 ft) long. They have long thread-like white fibers and the petioles are pure green with yellow edges and filifera-filaments, between the segments. The trunk is gray and tan and the leaves are gray green. When the fronds die they remain attached and drop down to cloak the trunk in a wide skirt. The shelter that the skirt creates provides a microhabitat for many small birds and invertebrates. If there is any red color present on petioles or trunk its not a pure filifera but a fila-busta hybrid.
Washingtonia filifera can live from 80 to 250 years or more.
Fan palms provide a habitat for desert bighorn sheep, hooded oriole, Gambel's quail, coyotes, and a rare bat species Lasiurus xanthinus that is especially fond of W. filifera groves. Hooded orioles rely on the trees for food and places to build nests. Both hooded orioles and coyotes play an integral part in seed distribution.
The palm boring beetle Dinapate wrightii (Bostrichidae) can chew through the trunks of this as well as other palms. Eventually a continued infestation of beetles can kill various genera and species of palms. The recent discovery of the red palm weevil (Rhynchophorus ferrugineus) in Southern California may pose a threat to many palms, with coastal garden W. filifera specimens already a known host. However, it seems that this species is resistant to the red palm weevil through a mechanism based on antibiosis.
Today, numbers and range of the desert fan palm are expanding due to global warming.
Historically, natural oases are mainly restricted to areas downstream from the source of hot springs, though water is not always visible at the surface.
Grazing animals can kill young plants through trampling, or by eating the terminus at the apical meristem, the growing portion of the plant. This may have kept palms restricted to a lesser range than indicated by the availability of water.
Today's oasis environment may have been protected from colder climatic changes over the course of its evolution. Thus this palm is restricted by both water and climate to widely separated relict groves. The trees in these groves show little if any genetic differentiation, (through electrophoretic examination) suggesting that the genus is genetically very stable.
Joshua Tree National Park in the Mojave Desert preserves and protects healthy riparian palm habitat examples in the Little San Bernardino Mountains, and westward where water rises through the San Andreas Fault on the east valley side. In the central Coachella Valley the Indio Hills Palms State Reserve and nearby Coachella Valley Preserve, other large oases are protected and accessible. The Santa Rosa and San Jacinto Mountains National Monument, and Anza-Borrego Desert State Park both have large and diverse W. filifera canyon oasis habitats.
The fruit of the fan palm was eaten raw, cooked, or ground into flour for cakes. The Cahuilla and related tribes used the leaves to make sandals, thatch roofs, and baskets. The stems were used to make cooking utensils. The Moapa band of Paiutes as well as other Southern Paiutes have written memories of using this palm's seed, fruit or leaves for various purposes including starvation food.
Washingtonia filifera is widely cultivated as an ornamental tree. It is one of the hardiest Coryphoidiae palms, rated as hardy to USDA hardiness zone 8. It will survive temperatures of −10 °C (14 °F) with minor damage, and established plants have survived, with severe leaf damage, brief periods as low as −12 °C (10 °F). The plants grow best in warm temperate climates with dry summers and wetter winters. Specimens outside of Mediterranean climates rarely exceed 15 metres (49 ft).
- Uhl, Natalie W.; Harold E Moore; John Dransfield (1987). Genera Palmarum: a classification of palms based on the work of Harold E. Moore, Jr. Lawrence, Kansas: L.H. Bailey Hortorium: International Palm Society. ISBN 9780935868302. OCLC 15641317.
- "Washingtonia filifera (Linden ex André) H. Wendl. ex de Bary". Tropicos.org. Missouri Botanical Garden. Retrieved 20 June 2014.
- "Washingtonia filifera (Linden ex André) H.Wendl. ex de Bary". PlantList. 2013. Retrieved 20 June 2014.
- Hogan, C. Michael (2009-01-05). "California Fan Palm (Washingtonia filifera)". iGoTerra. Retrieved 20 June 2014.
- "California Fan Palm". DesertUSA. Retrieved 20 June 2014.
- Clover, E.U. (April 1937). "Vegetational survey of the lower Rio Grand Valley, Texas". Madroño 4 (2): 41–66. JSTOR 41422215.
- Little, E.L. Jr. (1976). Atlas of United States Trees, Volume 3: Minor Western Hardwoods. Washington, DC: US Department of Agriculture, Forest Service. OCLC 241660.
- "Plant Profile for Washingtonia filifera (California fan palm)". Natural Resources Conservation Service. United States Department of Agriculture. Retrieved 20 June 2014.
- Govaerts, R. "Washingtonia filifera (Rafarin) H.Wendl. ex de Bary, Bot. Zeitung (Berlin) 37: LXI (1879).". World Checklist of Selected Plant Families. Retrieved 21 June 2014.
- Koerner, Claudia (2010-10-04). "Destructive exotic beetle found in Laguna Beach". Orange County Register (Santa Ana, California). Retrieved 20 June 2014.
- Nisson, N.; Hodel, D.; Hoddle, M. "Red Palm Weevil". Center for Invasive Species Research. University of California Riverside. Retrieved 20 June 2014.
- Dembilio, Ó.; Jacas, J.A.; Llácer, E. (August 2009). "Are the palms Washingtonia filifera and Chamaerops humilis suitable hosts for the red palm weevil, Rhynchophorus ferrugineus (Col. Curculionidae)?". Journal of Applied Entomology 133 (7): 565–567. doi:10.1111/j.1439-0418.2009.01385.x.
- Cornett, 2010
- Spencer, W. (1995). "Washingtonia filifera: Nevada's rejected ancient Palm.". www.xeri.com. Retrieved 21 June 2014.
- Spencer, W. (1995). "A report regarding: The Palm - Washingtonia filifera - in Moapa NV". www.xeri.com. Retrieved 21 June 2014.
- "Washingtonia filifera: Washington palm". RHS Gardening. Royal Horticultural Society. Retrieved 21 June 2014.
- Johnson (1998). Washingtonia filifera. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 11 May 2006.
- Floridata.com: Washingtonia filifera
- Cornett, J. W. 2010. Desert Palm Oasis. Nature Trails Press, Palm Springs, California.
- C. Michael Hogan. 2009. California Fan Palm: Washingtonia filifera, GlobalTwitcher.com, ed. Nicklas Stromberg
- Scanpalm – Washingtonia filifera
- Interactive Distribution Map for Washingtonia filifera
- Joshua Tree National Park: California Fan Palm oases
|Wikimedia Commons has media related to Washingtonia filifera.|
- USDA Plants Profile: Washingtonia filifera (California fan palm)
- UC Jepson Manual treatment — Washingtonia filifera
- Calflora Database: Washingtonia filifera (California fan palm)
- Washingtonia filifera in Flora of North America
- Living Desert.org — California Fan Palm
- Washingtonia filifera (California fan palm) — U.C. CalPhotos Gallery