From citrus grove markers to wildlife apartments, Riverside's iconic skydusters reveal surprising stories about our landscape and the creatures who call them home.
I internally shudder when someone asks me a question that assumes that I know everything about a particular local creature, plant or animal. In this case, my wife, Tracy, and I were entertaining Midwestern friends at Hanger 24 in Canyon Crest. The temperature had already cooled to 95 degrees by 6 p.m. The second part of the question should have been obvious.
"… they don't give a lot of shade. Why grow them? … "
While a response was running through my mind to the effect that you could find the shade if you knew EXACTLY where to stand, Ellen continued,
"… and they always are planted in rows."
I smiled, "During the boom of the citrus industry, the groves were so thick that it was easy to get lost in the sea of orange trees. The growers planted fast-growing palms to mark the roads on their property. Nowadays, they are a common roadside ornamental."
Tracy added, "Trees were used to mark property lines, too. If you climb the hill at the Citrus State Historic Park and look over Riverside's Greenbelt, you can still see palms along roads and at property limits."
Sometimes topping 80 feet, rows of palms are iconic symbols of Southern California. From motion pictures like La La Land to TV series like the Fresh Prince of Bel Air, the rest of the world is treated to the omnipresence of "skydusters" on our horizons, often bending to the late afternoon sea breeze.
While the palm family holds about 2,600 species, only one species accounts for the tall, thin feather-duster California palms. And it turns out that, like many Californians, that species has come from somewhere else. Washingtonia robusta, the Mexican fan palm, is native to coastal Baja California and Sonora. In the United States it has been successfully introduced far beyond its range, not only in Southern California, but also throughout the Southwest as well as Florida and Hawaii. As a subtropical species, it has made its way to suitable parts of Mediterranean Europe, Asia, and North Africa. In some cases, it creates self-sustaining populations and is invasive, for example, as seedlings are attempting to do in my backyard lawn.
California has only one native palm, Washingtonia filifera, the California fan palm. This species is the palm of canyons and oases in the California deserts. While California fan palm can be an ornamental, it is less tolerant of humidity and more tolerant of cold than its Mexican counterpart, making it more suitable for xeriscape planting. The trunk of Mexican fan palm is slender; the California fan palm trunk is more like a column. The leaves of Mexican fan palm are bright, shiny green; those of California fan palm are sea green or grayish green. These species are the only members of the genus Washingtonia (so named for George), and they are so closely related that they can successfully interbreed. The hybrids are called W. filibusta.
Despite the large number of palm species in the world, only three species make up the vast majority of the individuals commonly found in Riverside. We've already dealt with the ubiquitous sky-dusting Mexican fan palm and its desert-based relative, but there's another species that's quite different and easy to identify.
Palms are divided into two groups depending on the structure of their huge leaves (commonly called "fronds"). All palm species have compound leaves; that is, each leaf bears numerous leaflets. For one group of palms, the leaves are arranged radially, like fingers around, um, a palm; these are called the "palmate" species. The fan palms fall into this group. The other group have leaflets arranged along a central shaft (rachis), like the plume-lets along the shaft of a feather. Palms of this type are known as "pinnate."
The third common palm in Riverside is a pinnate species*. The Canary Island date palm, Phoenix canariensis, is often found as individual trees in older neighborhoods, such as Downtown, Rockledge, Eastside, and the Wood Streets. Phoenix canariensis is a stout, slow-growing tree that eventually can reach 30 to 60 feet. Its dense canopy of large feather-like leaves offers considerably more shade than the Washingtonias.
The genus Phoenix holds about 14 species. All are native to the Old World. The Canary Island date palm is indeed native to the Canary Islands and was introduced to California and elsewhere for ornamental purposes. The "true" date palm of commerce is P. dactylifera ("the finger-bearing Phoenix"); the ancient Greeks and Romans called this species "Phoenix" but whether it was in honor of the Phoenicians or the mythical cyclically self-consuming bird is unknown. Interestingly, Canary Island date palms are pollinated by insects.
The true date palm is composed of male and female trees whose inflorescences are unattractive to insects. This species is the only plant known that requires human pollination. Male inflorescences are cut from the male trees and tied to the inflorescences of the female trees. They are bagged together to protect the developing fruits from wind, rain, and sandstorms.
Speaking of dates begs the question of whether any of our ornamental palms bear edible fruit. The two fan palms and the Canary Island date palm have fruits characterized by a thin fleshy coating over a pea-sized seed. The taste of the sweet pulp of all three species is reminiscent of molasses, but the flesh-to-seed ratio makes eating them out of hand a bit frustrating. The indigenous people who lived adjacent to the fan palms ground the seeds into a meal.
Palm fruits also supplement the diets of coyotes, raccoons, opossums, and other mammals. In fact, creatures get more than food from our palms. The thick dead leaves that skirt the trunk can provide shelter. In Riverside, you often see and hear hooded orioles diving into their nests. More than once have I traced barn owls to the top of a palm tree. A good-sized cluster of fronds can provide an apartment house for the multi-family nests of acorn woodpeckers. Bats can find a good roost in a palm tree. Finally, unkempt palms can even act as a home for rats.
Owls, bats, and rats? Sounds a bit scary.
On second thought, are those tall, thin palms really feather-dusters or are they giant inverted witches' brooms?
After all, it's October.
*Two other pinnate species, the queen palm and the king palm, comprise almost all of the remaining Riverside palms. Their silver, slender, somewhat vase-shaped trunks distinguish them from Canary Island date palm as do their floppy, more delicate leaves.
Norm Ellstrand is an emeritus Distinguished Professor of Genetics and former Director of the California Agriculture and Food Enterprise at the University of California Riverside.
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