Geo-Joint: California Palms in Peril

While the vast majority of California’s palms are in the south, they can be cultivated well into the north.

As an icon, the palm tree finds itself in graphics anywhere an artist wants to say “Southern California.” The spirit and ambiance of the place is grasped in an instant when that long, slender trunk topped with splaying fronds is pictured. And it’s no wonder why—the plant is ubiquitous in the cities of the Southland, and in a lot of rural areas too. Palms became wildly popular in the late 1800s and early 1900s, establishing an expectation for residents as well as tourists, who saw so many images of them on the silver screen and in Hollywood fan magazines. There are over 2,500 species of palm trees, and while not all of them grow in California, many do. Out of all those, only one can truly call the state home: the native desert fan palm, or California fan palm, Washingtonia filifera. As one of its common names would indicate, it is a resident of the desert, originally growing in oases that developed along fault lines, where groundwater might come closer to the surface. Its shape is well known, having been planted extensively in urban areas. No less recognizable are a couple of other species so commonly seen in California: the Mexican fan palm, which can soar to 100 feet in height, and the Canary Island palm, with its stout, patterned trunk and broad, long fronds waving from a massive head.

The California fan palm, the only palm native to the state.

Though they generally stand as tall or taller than the trees they share the streetscape with, and sometimes have trunks of great girth, palms are not truly trees. In fact, in the technical sense, they are grasses. Like grasses, they have the characteristics of monocots—parallel veins in their leaves, roots that do not thicken as they grow, a pulpy rather than woody trunk, and an inability to repair wounds the way a tree can. In recognition of this difference, palms really should be called “palms” and not “palm trees.” Removing the tree reference is no disrespect to their contribution to our world, which not only includes decorative enhancement of cityscapes, but from some species delicious dates or coconuts (their fruit and seed), edible hearts of palm, handy and essential building materials for some cultures, and shelter for birds and small mammals.

Tall and skinny Mexican fan palms framing tall and skinny buildings in Los Angeles.

New enemy of California’s palms—the South American palm weevil.

Palms grow naturally in many temperate and tropical regions, and as mentioned earlier, have been propagated by the millions for visual enhancement in places like Los Angeles and Miami. Sadly, though, their numbers in Southern California are in decline. Palms face a number of pest and disease pressures which are beginning to seriously affect the overall health of the palm population.  One new arrival is the South American palm weevil, which made its way over the border of Baja and into the state in 2011. This weevil lays its eggs after burrowing into the base of a palm leaf. The hatchlings then eat their way into the central part of the palm, causing rot. In time, the structure is weakened, and eventually, the head of the palm will break off, in a scenario called sudden crown drop. Palms cannot regenerate after the loss of their head of fronds. The South American palm weevil is a double threat in that it is capable of transporting its parasite, the red ring nematode, also a palm killer. So far, that scourge hasn’t accompanied the weevils here, but it could be on its way. Another recent arrival is the polyphagus shot hole borer which, as you might guess, bores its way into the palms. It showed up in Los Angeles County in 2012 and has already made it to parts of five additional counties. That’s a lot of territory—counties in Southern California are fairly large.

Palms and Hollywood just go together.

Tinier organisms like the Fusarium fungus and pink rot attack palms that are overwatered or grow in especially damp soils. Fusarium is a native malady for palms in California, sometimes spread by the use of arborists’ chainsaws that have not been disinfected between trimming jobs. But even the native challenges that a palm might be expected to face are made more threatening as attacks now come from multiple directions. It’s not only health problems that are making life tough life for a Southern California palm these days—environmental factors are also casting a shadow on their future. For instance, the long California drought took a toll on palms and isn’t yet over, despite last winter’s abundant rain. And in Los Angeles, as palms fall away to drought, disease, and pests along city streets, planners and horticultural experts are choosing to replace them with leafy trees, for several reasons. In this age of climate change, a premium is put on trees because they can mitigate some of the carbon produced by the city’s enormous automobile fleet. Palms can’t do that. Leafy trees with wider crowns also provide more heat-lowering shade in the heat-island environment of a concrete city. In addition, officials are deciding to plant native trees that suck up less of the precious water supply than palms do. Environmentally speaking, then, palms are not an ideal choice for urban landscaping. Planners realize, though, that palms are iconic in parts of Los Angeles, and have agreed to keep them in certain neighborhoods or at particular locations that identify heavily with that look.

Is it sunset for palms in SoCal? Not entirely, but views like this may become less common.

At this point, however, palms in LA are dying off, a trend that also involves many other kinds of trees. So many will be lost soon that it will take 30 to 50 years to grow replanted specimens to the size and population prevalent in recent decades. And the slow-growing process is the only remotely economical option—replacing a fallen Canary Island palm with a mature individual taken from another location can run a cool $20,000. Not all palms are so pricey, but with all the other reasons to go to leafy trees, the dominance of the palm, like the superstardom of an aging Hollywood actor, will no doubt fade in coming decades. While palms will always grow in Southern California, the geographic mental image that future generations form may be decorated with different symbols of the California Dream.

Thinking you might want to see California’s palms before one more bites the dust? This beautiful wall map, available from Maps.com, will inspire your travel plans:

 

CLICK HERE TO VIEW THE MAP!


PHOTO CREDITS:

caption:  Is it sunset for palms in SoCal? Not entirely, but views like this may become less common.
source: flickr: Benson Kua (CC by SA 2.0)
caption: New enemy of California’s palms—the South American palm weevil.

source: Wikimedia Commons: Didier Descouens (CC by SA 3.0)

caption: Tall and skinny Mexican fan palms framing tall and skinny buildings in Los Angeles.
source: Wikimedia Commons: Waltarrrrr (CC by SA 3.0)
caption: The California fan palm, the only palm native to the state.
source: Wikimedia Commons: Bernard Gagnon (CC by SA 3.0)
caption: Palms and Hollywood just go together.
source: Wikimedia Commons: BenSherman (Public domain)

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