The California Fan Palm is notable as the only palm that is native to California; it is indigenous to riparian desert canyons in our State.
Beginning in the late 1800s, it was planted extensively in Santa Barbara, becoming a predominant feature along streets, in parks, and in private gardens. It was valued for its lush canopy of fronds and its stately straight trunk. It was especially impressive as rows of street trees standing on both sides of West Cabrillo Boulevard from State Street to Castillo Street.
Unfortunately, over time, California Fan Palms along our coast were found to be fatally susceptible to two palm diseases. These diseases decimated many fine palms, primarily those standing along our waterfront.
Fortunately, there are still many historic California Fan Palms left here to admire. These specimens are at least 100 years old. Though still magnificent, their canopies are much sparser than those found in warmer and dryer climates.
Te California Fan Palm has a single trunk that is gray to tan in color and truly massive, reaching 2- to 3-feet in diameter at the base and a height of 80-feet.
Each trunk has a terminal canopy of long palmate (hand-like) fronds, which are attached to the trunk with 6-foot-long petioles (stems) that are 6-inches broad at the base and armed with light yellow teeth.
Each frond is 5- to 6-feet across and divided into 32 or more fanned segments. When young, the fronds are green and erect; as they age, they develop a grayish color and their segments droop.
Long, white, thread-like filaments gradually appear between the segments and dangle toward the ground.
As the fronds die, if not pruned off, they remain on the trunk (persist), hanging down to form a dense “shag” or “skirt” around the trunk. This skirt provides a habitat for small birds, invertebrates, and rodents.
The California Fan Palm is “monoecious”, which means each palm bears both male and female flowers. From June to August, numerous, tiny, white flowers emerge on 6- to 10-foot-long branched inflorescences (flower-bearing stalks) that appear between the lower fronds.
After pollination, the female flowers develop ovoid small (1/3-inch long) drupes (berries with a single seed at the center), which are green when young and turn a deep blue to black when ripe. Locally, flowering and fruit formation rarely occurs.
While the California Fan Palm is native to California, it is also endemic to widely separated relict populations in the desert canyons of southwestern Arizona, Baja California, and northwest Mexico.
The indigenous people in its native ranges utilized this palm for many purposes, including food from its fruit, material for baskets, sandals, and roof thatch from its fronds, and utensils from its petioles.
The California Fan Palm has several other common names including “Desert Fan Palm”, “California Palm”, Petticoat Palm”, and “Arizona Fan Palm”.
It is in the Arecaceae (palm) plant family. Its botanical name is Washingtonia filifera. The genus name, Washingtonia, honors our first president, George Washington. The specific epithet, filifera, is from Latin and means “thread bearing”, referring to the long filaments that hang from between the leaf segments.
California Fan Palm is rarely planted in our area any longer, since it is susceptible to two nasty fungal diseases, “Pink Rot” and “Diamond Scale”. Pink Rot infects the epical meristem (the tissue at the very top of the palm that creates new fronds) and can kill the tree. Diamond Scale infects the fronds, causing a decline in tree vigor that results in a sparse canopy. Both of these fungi thrive in areas near the ocean that regularly have cool humidity and fog (like our “May Gray” and “June Gloom”).
As our infected California Fan Palms succumbed to these diseases, they have been replaced with their closest palm relative, the Mexican Fan Palm (Washingtonia robusta), which is disease resistant. To tell them apart, note that the Mexican Fan Palm has a trunk diameter approximately one-half that of the California Fan Palm and has a canopy that is greener, more rounded, and fuller.
California Fan Palm grows best in dry desert heat, where fungal diseases rarely survive. However, it is found naturally growing only in riparian environments in desert canyons – areas where continual ground and surface water from natural drainage and/or springs create oasis conditions. It can generally be considered drought-tolerant; nevertheless, ample available water is required for it to thrive.
California Fan Palms can be viewed in their full grandeur in many desert locations: Tahquitz Canyon (near Palm Springs); Indio Hill Palms State Reserve; Coachella Valley Preserve; San Jacinto Mountains National Monument; and, Anza-Borrego Desert State Park.
In our community, mature California Fan Palms can be seen at several places: in the 200 block of Palm Avenue; in the 300 block of Santa Barbara Street; at 2029 Oak Avenue; at the Santa Barbara County Court House (south and west sides); in Plaza Vera Cruz Park; in Chase Palm Park; on the grounds of Old Mission Santa Barbara; and, in the parking lot of lower Manning Park.
Tree-of-the-Month articles are sponsored by Santa Barbara Beautiful, whose many missions include the increase of public awareness and appreciation of Santa Barbara’s many outstanding trees and, in a long-time partnership with the City Parks & Recreation Department, the funding and planting of trees along the City’s streets.
Those who wish to honor a special someone can do so with an attractive commemorative marker that will be installed at the base of an existing street tree in the City of Santa Barbara. Because Santa Barbara Beautiful has participated in the planting to date of over 14,000 street trees, there are plenty of trees from which to choose! Application forms are available on the Santa Barbara Beautiful website, www.sbbeautiful.org.
Article and Photos by David Gress
