Monday, April 11, 2011

That Tropical Feeling: Palms in the Desert

Living in the Sonoran desert can get a little dry at times, so one way we delude ourselves into feeling like we actually live in a tropical paradise or on the shores of a Caribbean beach is to plant palm trees. Our need for desert denial is so great that, next to the faux saguaro, one of the most common tech art designs for cell towers is a palm. But did you know that there is actually one species of palm that is native to Arizona and the Sonoran Desert?

The Desert Fan Palm (Washingtonia filifera) is a relict of more temperate days in these parts dating to as long as over six million years ago. Today, small wild groves are still tucked up in secluded canyons and near springs in the southwest where they have a reliable source of water. Just north of Phoenix, the privately owned Castle Hot Springs Resort includes natural springs that nurture a palm forest, as well as developed springs and carefully manicured groves. West of Phoenix at the KOFA National Wildlife Refuge, a small wild grove persists high up in a narrow shady canyon. Over in California, you can relax in the shade of native palm oases at Joshua Tree National Park.

Closer to home, all around us in the suburbs of Phoenix, our native palm is one of about two dozen species that have been introduced from all over the world for landscaping. One of the best places to view what most resembles a natural Desert Fan Palm grove is at the Phoenix Zoo, where the palms have developed massive “skirts” of dead fronds that surround the stout trunks. Groves in their natural, unpruned form are habitat for abundant wildlife, including a rare bat species, desert rats, lizards, snakes, many type of insects and birds, bighorn sheep and coyotes. Hooded Orioles use palm fibers to weave beautiful nests that hang in the protective shade of the leaves. For indigenous people, palm groves were a source of fiber that was woven into cloth and twined for cordage, leaves for making thatched roofs, walls and baskets, plus fruit and seeds for food.

Unfortunately, the benefits of palms for wildlife are not so endearing to many contemporary homeowners, who prefer not to welcome so many critters into their yards. Palm skirts are also regarded as a fire hazard, although in wild areas, occasional fire actually rejuvenates the groves by clearing out dense brush and creating fertile ground for new trees. Healthy mature palms are fire resistant, and will usually survive a wildfire.

Other notable palms in the suburbs are the majestic date palms, whose Latin name, Phoenix dactylifera, happens to include the name of our fair city. Date palms differ from fan palms in having long feather-shaped leaves, and also produce sweet succulent fruit. A relict of the commercial groves that were once abundant in the area is ASU’s Polytechnic Campus Date Palm Grove, which boasts over fifty different cultivars and is reputed to be the largest date palm collection of any public garden in the country. These palms represent a rich history of human civilization centered in the Middle East, where palms were critical to the development of early agricultural societies and highly valued for trade. The importance of date palms is recorded in drawings and temples of ancient peoples dating back to 7000 years ago. According to Islamic tradition, the original tree of life in the Garden of Eden is said to have been a date palm.

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