Washingtonia is a genus of palms, native to the southwestern United States (in southern California, southwest Arizona, Nevada, and Texas) and northwest Mexico (in northern Baja California and Sonora). Both Washingtonia species are commonly cultivated across the Southern United States, the Middle East, southern Europe, and north Africa, where they have greatly hybridized.
They are fan palms (subfamily Coryphoideae), with the leaves with a bare petiole terminating in a rounded fan of numerous leaflets. The flowers are in a dense inflorescence, with the fruits maturing into a small blackish-brown drupe 6–10 mm diameter with a thin layer of sweet flesh over the single seed.
There are two species:
- Washingtonia filifera (Lindl. ex André) H.Wendl. California Washingtonia, Northern Washingtonia, California fan palm, or Desert fan palm. Tree to 23 m tall; leaves large, with petiole up to 2 m long, and leaflets up to 2 m long. Inflorescence to 5 m long; flowers white; fruit oval. Southwestern USA, just into extreme northwest Mexico. Palms are often found at the base of mountains, hills and form around desert oasis in the southwest. They are used in landscaping, particularly in southern counties of California.
- Washingtonia robusta H.Wendl. Mexican Washingtonia or Southern Washingtonia. Tree to 25 m tall; leaves smaller, with petiole up to 1 m long, and leaflets up to 1 m long. Inflorescence to 3 m long; flowers pale orange-pink; fruit spherical. Northwest Mexico. (Teresa Ribeiro et al.).
The fruit is edible, and was used by Native American people as a minor food source. They are also eaten by birds, which disperse the seeds in their droppings after digesting the fruit pulp. Washingtonia species are also used as food plants by the larvae of some Lepidoptera species, including Paysandisia archon.
Both species are cultivated as ornamental trees, widely planted in California in particular, but also in Florida, extreme southwest Utah, Arizona, southern New Mexico, Texas, the Carolinas and the Mediterranean region in southern Europe and north Africa, parts of Australia, and the leeward sides of the Hawaiian Islands. W. filifera is modestly hardy in drier climate and able to survive brief temperatures in the vicinity of -15 °C (10 °F), provided the air and soil are not too wet, and the afternoon temperatures are not too cold. Intolerance of wet, prolonged cold is the main reason the filifera species cannot grow properly in temperate marine climates. W. robusta is less sensitive to moisture than filifera, but far more easily damaged by cold.
- H.A. Wendland, Botanische Zeitung 37:1xi, 68, 148. 1879 (conserved name)
- Kew World Checklist of Selected Plant Families
- Riffle, Robert L. and Craft, Paul (2003) An Encyclopedia of Cultivated Palms. Portland: Timber Press. ISBN 0-88192-558-6 / ISBN 978-0-88192-558-6
- German botanist Hermann Von Wendland designated the name in 1879. http://www.public.asu.edu/~camartin/plants/Plant%20html%20files/washingtonia_filifera.htm
- Flickr: Washingtonias in Russian National Subtropical Garden
- Flora of North America: Washingtonia
- Scanpalm: Washingtonia
- [German botanist Hermann Von Wendland designated the name in 1879. http://www.public.asu.edu/~camartin/plants/Plant%20html%20files/washingtonia_filifera.htm]