Tuesday, March 9, 2010

California Fan Palm

The California fan palm is the only native palm to the western United States. It is found in the inland deserts of Southern California, southern Nevada, southern Arizona and extreme northwest Mexico at elevations between 500 and 1,000 feet. It is the palm tree found in the desert oases that I love. These oases are near the source or just downstream from the source of warm or hot springs in areas that have been protected from colder climatic changes over the course of its evolution. So it is restricted by both water and climate to widely separated surviving groves and the trees in these groves show little genetic differentiation. One of my favorite desert spots is Corn Springs, about 30 miles west of Blythe in the Chuckwalla Mountains, eight miles down a dirt road from the I-10 freeway. After driving through hard core desert with little vegetation, a sight like that below is really appreciated and awe inspring.
 Because of urbanization and increased agriculture, ground water has been lowered which has decreased the amount of water available in palm oases, creating a threat to their existence. I have noticed over the last 25 years that the palm trees at Corn Springs are not as healthy as they once were. The view below is from a hill over-looking Corn Springs and the valley it is in.
A closer view of the Corn Springs palms.
The California fan palm can grow up to 75 feet tall (or almost 100 feet in exceptional growing conditions). I think the most healthy fan palms I've seen are those at Borrego Palm Canyon, below.
The palms in the main grove are enormous. Of course, they are right in the path of openly running water. You see people off to the right below, which gives perspective on how tall these trees are.
The trunk is unbranched, is two to three feet in diameter and is usually 20 to 60 feet high. It has fan-shaped palm fronds (leaves) three to five feet long with hooked spines along the edges. The palm fronds spread from the top of the tree. When the palm fronds die, they bend downwards and form a skirt around the trunk which sometimes gives it the name "petticoat palm." 
The skirt provides a habitat for many creatures. The palm can live from 80 to 250 years. The proximity to water attracts species such as the bighorn sheep, Gambel's quail and mourning dove. The palms below are at Hidden Spring in the Mecca Hills at the east end of the Coachella Valley and just north of the Salton Sea (Andrew, Sam and Mark Martinsen are in the foreground). It is in as harsh a country as I have ever been in. Very little vegetation, very little rainfall. This particular area is closed to the public part of the year because it is used so heavily by bighorn sheep and other animals for water. In that context, these trees are a wonder.
The picture below is of Sheep Hole Oasis in the Mecca Hills, very near Hidden Spring. There are three California fan palms in a wash in the fore-center of the picture. It provides a better visual of how desolate the country is and how hardy these palms have to be. Hidden Spring is further back in the canyons below.
A closer view of the Sheep Hole Oasis palms, the picture taken from a hill above.
The dead-frond skirt provies nesting and roosting sites for hooded orioles and the rare western yellow bat. The berries are eaten by the hooded oriole and coyote which also aides in the proliferation of the palms. At Hidden Spring, we have seen coyote scat just full of palm seeds. In the spring, clusters of white, three-lobed, funnel-shaped flowers, about 1/2 inch long, hang down from leaf bases. It produces elliptical black berries, about 1/2 inch in diameter. The berries have a brown seed surrounded by a thin, sweet pulp, which the Indians ate fresh or dried. They also ground the seeds into flour. The Cahuilla Indians used the leaves to make sandals, thatch roofs and baskets. Fire is important for the reproduction and maitenance of the palm oases. Fire opens up the understory, permitting fire-tolerant palms to become established. The black trunks of these palms in Borrego Palm Canyon evidences the fact that they are tolerant of fire.
The fire kills intolerant plants, such as mesquite, enhances the water supply and releases established shade intolerant palms. Fire has also visited the palms at Corn Springs, below.
A few more photos of California fan palms in Borrego Palm Canyon.
This beautiful grove is just below the south fork of Borrego Palm Canyon, a difficult hike into the rugged canyon.
Finally, additional palms in Borrego Palm Canyon.
California fan palms are now used as ornamental trees in gardens and we have them growing as volunteers in our backyard. We have allowed them to grow for the last 19 years and they are now getting quite tall.

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