If you close your eyes and imagine a typical Southern California landscape, chances are that you've pictured at least one palm tree, if not several, rising from the ground. But despite the diversity and ubiquity of palms in the Los Angeles area, only one species—Washingtonia filifera, the California fan palm—is native to California. All of L.A.'s other palm species, from the slender Mexican fan palms that line so many L.A. boulevards to the feather-topped Canary Island date palm, have been imported.
Although they conjure the image of Los Angeles as desert oasis, L.A.'s palm trees owe their iconic status more to Southern California's turn-of-the-century cultural aspirations and engineering feats than to the region's natural ecology. Though watered in some places by perennial streams like the Los Angeles River, Southern California's pre-1492 landscape was decidedly semi-arid, a patchwork of grassland, chaparral, sage scrub, and oak woodland. As monocots, palms are actually more closely related to grasses than they are to woody deciduous trees. They need an abundance of water in the soil to grow successfully, and so they—like the manicured lawns they often adorn—rely on the vast amounts of water that Southern California imports from distant watersheds.