Plant Fact Sheet

Arecaceae (Palmae)
California Fan Palm
Washingtonia filifera

During the Miocene and the Pliocene Epoch, Washingtonia filifera, or California Fan Palm, had a more extensive distribution reaching further into the Mojave Desert and also ocurring westward to the Pacific Ocean. Climatic and geologic changes eventually decreased the range of the California Fan Palm. Today California Fan Palm can be found in the western Sonoran Desert in southeastern California with outlier populations in western Arizona and northern Baja. Because California Fan Palm needs a year round source of water, many groves are found along the San Andreas Fault and associated fault zones where water has an outlet to the surface.

Washingtonia filifera, the only palm native to California, forms open to dense groves with each specimen reaching a height of 30-50 feet and a diameter of 1-2 feet. When the skirt or shag of the palm is accounted for the total diameter can increase to approximately 8 feet. The skirt of the fan palm is formed as each dying palm frond bends down towards the trunk forming a layered ‘skirt’ that will eventually cover the majority of the trunk. It is the thickness of these majestic skirts that accounts for the dense shade many oases provide.

Considering the relative lushness of these desert oases, one can begin to understand how animals, including humans, could survive so successfully in such a harsh environment. It was the Cahuilla Indians who came to fully appreciate the richness these oases had to offer. That there is a strong association between Cahuilla archeological sites and palm groves should not be surprising considering that the groves provided them with water, food, shade, and the raw materials needed for domestic structures.

During the late summer through early fall the Cahuilla harvested the fruit of Washingtonia filifera. The seeds could be eaten fresh or dried and stored in ollas for later use. In time of famine the Cahuilla could rely on the palm hearts as a source of food. Palm leaves were used to make sandals while the palm stems were used to fabricate cooking utensils. The entire palm frond provided the roofing and siding material used for the Cahuilla homes and ramadas. A replica of a “kish”, a typical Cahuilla dwelling, is displayed in the Indian Ethnobotanical Garden at The Living Desert.

Most impressive is the Cahuilla understanding of the fire ecology associated with Washingtonia filifera. Probably after observing the effects of a naturally occurring fire, the Cahuilla came to realize that burned stands of palms flowered and fruited at significantly higher rates. It is believed that the Cahuilla initiated prescribed burns every four years in order to increase fruit production, remove debris, and to help promote seedling growth. Today fire is believed to be a naturally occurring benefit for the California Fan Palm.

Unfortunately many oases have been destroyed due to the strain urban and agricultural development has placed on the ground water supply. It is a well known fact that groundwater pumping has lowered the water table and that Washingtonia filifera is sensitive to any change in the water level. The lowering of the water level then can be held at least partially responsible for the loss of many palms. This loss is significant since so much of our native wildlife relies on the palm groves for water, food, and shelter. At The Living Desert we have made efforts to educate the public about these endangered ecosystems. We have created a replication of a natural oasis and provided interpretive text throughout the garden. The skirts have been left on the California Fan Palms to enhance the natural look of the garden and to promote the use of the garden by our local wildlife. The garden is impressive and enjoyable any time of the year.