California Fan Palm - Washingtonia filifera H. Wendl.
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W. filifera palms showing marcesant leaves
Fig. 1
W. filifera palms showing marcesant leaves with human on the left (for scale)

Photo of W. robusta (left) W. filifera (right)
Fig. 2
W. robusta (left) W. filifera (right)

Washingtonia filifera habit. Coachella Valley Preserve, Thousand Palms Oasis
Fig. 3
W. filifera habit. Coachella Valley Preserve, Thousand Palms Oasis


Desert Palm - W.filifera, Indian Canyons - Palm Springs Ca.
Fig. 4
 Desert Palm - W.filifera, Indian Canyons - Palm Springs Ca.

W. filifera with open canopy
Fig. 5
W. filifera with open canopy

W. filifera adaxial hastula

Fig. 6
W. filifera abaxial surface with costa

W. filifera adaxial hastula

Fig. 7
W. filifera adaxial hastula

Close-up

W. filifera teeth along petiole margins

Fig. 8 
W. filifera teeth along petiole margins

W. filifera close view of teeth along petiole margin
Fig. 9
W. filifera
close view of teeth along petiole margin

W. filifera leaf segment marginal fibers

Fig. 10
W. filifera
leaf segment marginal fibers

W. filifera inflorescence branching

Fig. 11
W. filifera inflorescence branching

Washingtonia filifera close up, Torrelamata, Torrevieja, Alicante, Spain

Fig. 12
W. filifera close up, Torrelamata, Torrevieja, Alicante, Spain 

Inflorescense
Fig. 13
Inflorescense

Fruit

Fig. 14 
Fruit

Seeds

Fig. 15
Seeds

Bark

Fig. 16  
Bark

Trunk
Fig. 17

Trunk with the boots trimmed

Fig. 18

Washingtonia filifera seedling

Fig. 19
W. filifera
seedling

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Scientific name
W. filifera H. Wendl.
Pronunciation
wosh-ing-TOE-nee-er-uh
Common names
California Washingtonia Palm, Desert Fan Palm, Petticoat Palm, American Cotton Palm, Cotton Palm, Washington Palm
Synonyms
Neowashingtonia filifera (Linden) Sudw.; Pritchardia filifera Linden ex André; W. filamentosa (H.Wendl. ex Fenzi) Kuntze; W. sonorae S.Watson
Relatives
Thread palm, Mexican Palm (W. robusta)
Family
Arecaceae/Palmae
Origin
Not native to North America
USDA hardiness zones
9A-11
Uses
The trees are especially valuable as avenue plants, and are widely used as such in southern California and Arizona; they also make handsome specimens
Height
To about 40 to 50 ft (15m), sometimes 80 ft (24m)
Spread
10-15 ft (3-4m)
Crown
Symmetrical; large, dense canopy of several dozen leaves
Growth rate
Moderate; 36 in. (91 cm) a year
Trunk/bark/branches
Branches don't droop; not showy; typically one trunk; thorns
Pruning requirement
Needed for strong structure
Leaves
Evergreen; immense, fan-shaped, costapalmate, grayish-green leaves are 3-4 ft (1-1.5 m) long and 6-7 ft (1.5-2 m) wide, dividing about halfway into 50-70 pointed segments that bend and split at the tips with threads in between 4; thorns on margin of petioles
Flowers
Numerous white to apricot, bisexual flowers are borne on 9-15 foot arching, branched inflorescences that hang down from among the leaves; not showy 4
Fruit
Fruits are spherical to pear-shaped, less than 0.5 in (1 cm) in diameter and brownish-black to black when ripe; berry-like, small fruits are brownish-black drupe and have a thin, sweet pulp that tastes somewhat like dates or butterscotch; each fruit contains a single seed 4
Light requirement
Full Sun
Soil tolerances
The trees are widely adaptable to most soil conditions, well-drained
PH preference
9A through 11
Drought tolerance
High drought tolerance but will do well with some moisture
Wind tolerance
Wind-tolerant
Aerosol salt tolerance
Moderate
Soil salt tolerance
Moderate salt tolerance allows it to be used close to the coast in several of the southern states
Cold tolerance
They are hardy to 18° F (-7º C)
Invasive potential *
There is little invasive potential
Pest resistance
Resistant to pests/diseases; resistant to Verticillium wilt
Known hazard
The dead fronds are known to be a fire hazard and a popular bedding roost for rodents and, because of this must be removed by law in some areas 3
Petioles of mature palms are armed along the margins with curved thorns (Fig. 9)

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Reading Material
California Fan Palm ext. link
Washingtonia filifera: Desert Palm from the University of Florida pdf
Fan Palm, Washingtonia filifera (L. Linden) H. Wendl. from the USDA Natural Resources Conservation Service pdf



Origin

California fan palms occur near streams and springs on borders of the Colorado Desert of California and southwest Arizona. The related W. robusta is native to arid regions of Sonora and Baja California, Mexico.  The genus is named after George Washington, 1732--1799, the first president of the United States. 4

Description
Solitary, columnar, upright to 50 feet (15 m) tall and 100-150 cm diameter, covered with a skirt of marcescent leaves (unless removed for landscape appeal). Old leaf bases usually fall away after many years, to leave a smooth gray stem with closely spaced leaf scar rings. 1
These palms are extensively grown in many parts of California and are common along the Gulf Coast and in Florida, as well as in other parts of the world, particularly those with Mediterranean-type climates. 1
The cylindrical, closely ringed and fissured trunks are swollen at the base and covered with a "petticoat" of dead, pendant leaf stalks, extending almost to the ground. They are not a particularly good choice for container culture because of their relatively fast rate of growth. 1
The specific epithet filifera means "thread-bearing". 5

Leaves
The leaves are costapalmate, induplicate, split about half the blade length into numerous segments with pendulous tips and threads (marginal fibers) hanging between segments. Several grayish-green leaves form an open crown. Petioles split, armed with curved teeth. The base of the lower surface of the leaf blade scantly covered with near white pubescence. The adaxial hastula is prominent with tattered margins. The leaves are edged with prickles and stand well apart in an open crown. 1

Flowers
The California fan palm produces numerous branching flower clusters that project out and often downward from the leaf crown. The bisexual blossoms are white and yellow and give rise to oblong or round red-black fruit, each about a 0.5 in (1.3 cm) in diameter. 5

Fruit
Does not attract wildlife; not showy; fruit/leaves not a litter problem. 3

Diagram of the seed from the USDA Natural Resources Conservation Service

Pollination
Pollination is by wind and various insects.

Propagation
Propagation is from seed, which germinate in six weeks to two months. 4

Planting
Plant this palm only on soil which is extremely well-drained to prevent trunk or root rot. Moderate salt tolerance allows it to be used close to the coast in several of the southern states. This palm could be tried more in well-drained sites as a replacement for Washingtonia robusta which grows very tall with a skinny trunk. 3

Pruning
The lower leaves persist on the tree after they die, forming a dense, brown, shaggy covering below the living, grey/green, broad, fan-shaped leaves, giving it the common name of Petticoat Palm. These dead fronds are known to be a fire hazard and a popular bedding roost for rodents and, because of this, must be removed by law in some areas. 3

Fertilizing
The trees respond to an occasional light fertilizing, particularly when young. Older trees seem to do well without regular fertilizing.

Irrigation
The palms are drought-tolerant but appreciate some moisture. In native stands they always grow near springs or other moist spots. 4 Will frequently develops trunk or root rot when over-irrigated. 1

Pests/Diseases
Scales while young, palm weevil in old age, palm leaf skeletonizer and a variety of scales at any time can infest this palm. Trunk or root rot in wet soils may infect this tree. 3
Resistant to verticillium wilt. 1

More Pests and Diseases

Food Uses
The small fruits are harvested when ripe and eaten fresh or dried, or made into jellies and drinks. The seeds are also edible and were widely used by Native Americans who ground them into meal for making bread or porridge. 4
Palm oases were important habitation sites for the Cahuilla and other tribes. The fan palm provided abundant fruit that was relished by the Cahuilla. It was eaten fresh or dried in the sun and then stored in ollas for future consumption. The seeds and flour were pounded into a meal, mixed with other flours and water to a mush. A beverage was made by soaking the fruit in water. 8

Other Uses
Desert Fan Palm is better suited to the home landscape since it grows more slowly and is shorter. This also allows it to be used in more garden applications, such as containers or grouped together as a mass planting. 3
Additionally, the leaves were used for clothing, sandals, thatching, and basketry materials, the fruit stalks for fire drills, and leafstalks for household utensils. The Cahuilla, Diegueno, and Luiseno of southern California used the leaves for matting, stuffing and in rough ropemaking. 8
Better for the home landscape than the widely used W. robusa because it grows more slowly and is shorter, is also a good tree to use for dry urban landscapes, for example in Texas, Arizona and California. Select W. robusta for an irrigated landscape and for the eastern U.S. 3

General
Plant this palm only on soil which is extremely well-drained to prevent trunk or root rot. This palm could be tried more in well-drained sites as a replacement for W. robusta which grows very tall with a skinny trunk. But over-irrigation and rainy weather could initiate root rot. They reportedly suffer and often die from root rot when irrigated. 3
May be confused with: Washingtonia robusta, but that species has a tapered stem, roughly twice as wide at the base as the apex, and bright green leaves forming a dense crown, rather than the columnar stemmed W. filifera, with grayish-green leaves and long petioles forming an open crown. 1
There is a persistent myth that these palms were brought to the Americas by the ancient Nubian's/Egyptians and their seeds were distributed in the waterways of the Western Californian area. 6

Washingtonia  filifera distribution map
Fig. 20
Fan Palm, W. filifera (L. Linden) H. Wendl. distribution map



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Bibliography

1 Anderson, P.J. “Washingtonia filifera." idtools.org/id/palms/palmid/. Identifying Commonly Cultivated Palms. A Resource for Pests and Diseases of Cultivated Palms. Florida Department of Agriculture and Consumer Service, Division of Plant Industry and Identification Technology Program, CPHST, PPQ, APHIS, USDA; Fort Collins, CO.  2011. Web. 25 Mar. 2014.
2 Elliott, Monica L. "Bud Rot of Palm." edis.ifas.ufl.edu. This document is PP-220, one of a series of the Plant Pathology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date Oct. 2005. Revised July 2012.  Web. 25 Mar. 2014.
3 Gilman, Edward F. and Watson, Dennis G. "Washingtonia filifera: Desert Palm." edis.ifas.ufl.edu. This document is ENH-826, one of a series of the Environmental Horticulture, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Publication date November 1993. Reviewed Feb 2014. Web. 26 Sept. 2015.
4 "Hardy Edible Palms: California Fan Palm." crfg.org. N.d.  Web. 25 Apr. 2014.
5 Spencer, W. "A report regarding: The Palm - Washingtonia filifera - in Moapa NV." xeri.com. 1995. Web. 10 Dec. 2015.
6 "Washintonia filifera." wikipedia.org.  N.d. Web. 10 Dec. 2015.
7 Haynes, Jody and McLaughlin, John. "Edible Palms and Their Uses." edis.ifas.ufl.edu. This document is Fact Sheet MDCE-00-5- of the UF/Miami-Dade County Extension Office.First published Nov. 2000. Web. 14 Dec. 2015.
8  "Fan Palm, Washingtonia filifera (L. Linden) H. Wendl." plant-materials.nrcs.usda.gov. Revised 19 June 2000. Web. 26 12 Dec. 2015.

Photographs

Fig. 1,2,3,6,7,8,9,10,11 Anderson, P.J. Washingtonia filifera. 2011Identifying Commonly Cultivated Palms. In A Resource for Pests and Diseases of Cultivated Palms. Florida Department of Agriculture and Consumer Service, Division of Plant Industry and Identification Technology Program, CPHST, PPQ, APHIS, USDA; Fort Collins, CO. idtools.org/id/palms/palmid/. Web. 25 Mar. 2014.
Fig. 4 Cory, Joyce. Indian Canyons - Palm Springs Ca. Mature palms stand protectively around their young. Washingtonia filifera is the only palm native to California. 2012. flickr.com. Web. 13 Dec. 2015.
Fig. 5,17,18 M. Ritter, M, Mark, W. and Reimer, J. SelecTree. Washingtonia filifera Tree Record. 1995-2015. selectree.calpoly.edu. Web. 12 Dec. 2015.
Fig. 12 Martin, Javier. W. filifera close up, Torrelamata, Torrevieja, Alicante, Spain. 2010. wikimedia.org. Web. 12 Dec. 2015.
Fig. 13 Kaakkara, Shijan. Washingtonia filifera Inflorescense. 2013. wikimedia.org. Under (CC BY-SA 3.0). Web. 12 Dec. 2015. 
Fig. 14 Anderson, M. Kat. The PLANTS Database. 2014. USDA, NRCS. National Plant Data Team, Greensboro, NC 27401-4901 USA. plants.usda.gov. Web. 25 Mar. 2014.
Fig. 15 Hurst, Steve. The PLANTS Database. 2014. USDA, NRCS. National Plant Data Team, Greensboro, NC 27401-4901 USA. plants.usda.gov..Web. 25 Mar. 2014.
Fig. 16 Monroe, Gary A. The PLANTS Database. 2014.USDA, NRCS. National Plant Data Team, Greensboro, NC 27401-4901 USA. plants.usda.gov. Web. 25 Mar. 2014.
Fig. 19 RickP. Washingtonia filifera seedling. 2007. wikimedia.org. Under (CC BY 2.5). Web. 12 Dec. 2015.
Fig. 20 Fan Palm, W. filifera (L. Linden) H. Wendl. distribution map. N.d. USDA, NRCS. The PLANTS Database National Plant Data Team, Greensboro, NC 27401-4901 USA. plants.usda.gov. Web. 15 Dec. 2015.

*   UF/IFAS Assessment of Non-native Plants in Florida's Natural Areas

Published 25 Mar. 2014 LR. Updated 15 Dec. 2015 LR
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