Here's the whole article How Did L. A. Become Become a City of Palm? And Other Questions About California Trees.
But here's the bit about my bête noire:
NM: How did palms become such a potent symbol of L.A.? And when you look into the future, do you see their iconic status eroding away, much as pepper trees lost theirs?
JF: You're right: A century ago, the iconic street tree of Los Angeles was not any kind of palm, but the pepper tree (Schinus molle), a species of sumac native to the arid zone of South America, with its distinctive feathery foliage and scarlet berries. This tree served as Southern California's answer to the weeping willow. On my book's Facebook page, I've posted vintage postcards and greeting cards that just show just how emblematic pepper trees used to be. Today, I bet most Angelenos wouldn't be able to pick one out from a line-up of trees. (If you want to get a sense of what the L.A. treescape once looked like, drive around Rancho Palos Verdes and Rolling Hills Estates, which still have splendid peppers.)
Palms replaced peppers in the built environment and the psychic landscape of L.A. for a few reasons. First, many of the pioneer pepper trees were torn out in the early twentieth century because they acted as a reservoir for black scale, an insect that damaged citrus groves. In 1930 Los Angeles followed the example of the citrus colonies and banned further street planting of the species.
Meanwhile, in the 1920s and 1930s, L.A. was busy building its modern grid of automobile boulevards, and the city's newly established Division of Forestry was looking for standardized street trees.
In advance of hosting the Tenth Olympiad in 1932, City Hall announced a 10-year plan -- a Depression-relief works project -- to set thousands of trees along major boulevards. Metropolitan foresters chose not to reproduce the familiar street trees from the pioneer era -- acacias, eucalypts, and peppers.
In the age of streetside parking, sidewalks, sewers, and utility poles, these leafy, rooty growers acquired bad reputations. In contrast, palms held out the promise of symbiotic infrastructure: they could provide beautification without dropping fruit, buckling concrete, or breaking pipes and wires.
The species planted most prevalently by city crews was Mexican fan palm (Washingtonia robusta), native to Sonora and Baja. City officials probably had no inkling these seedlings would grow so tall. The species wasn't singled out for aesthetics. Rather, it was hardy and it was cheap.
Prior to the mid twentieth century, when these uniform rows of Mexican fan palms reached maturity, fronds were not a leading feature of the urban landscape, despite the fact that tourism boosters had incessantly advertised the palminess of Greater Los Angeles.
The most visible species was Canary Island date palm (Phoenix canariensis), which wealthy homeowners habitually planted in pairs along their front walkways. Although San Diego, Santa Barbara, Redlands -- and even Sacramento -- were decades ahead of Los Angeles in cultivating a palmy landscape, L.A. had better boosters.
"We used to go down to the Capitol Theater in Sioux City, Iowa, and sit there and watch Bing Crosby movies," recalled one transplant, "and I said, 'Man, is that what it's like out there? I got to get out there!' See how naive we were. Why, hey. They could paint those palm trees in the back of those movie sets as fast as you could leave."
Thanks to the entertainment industry, Mexican fan palms acquired associations with sex, glamour, and celebrity. As it happened, the city's roadside plantings achieved spectacular heights in the same era that Hollywood became a dominant force in global entertainment. All of those thousands of films and TV shows shot outdoors in postwar Los Angeles cemented an association in people's minds: tall, skinny palms = L.A. Mexican fan palms became the icon of verticality in the postwar metropolis, complementing the freeway, the icon of horizontality.
The city won't lack for palms any time soon. However, the era of the "skyduster" Mexican fan palm will end later this century as the even-age cohort of street trees passes away. Since fan palms don't provide adequate "ecosystem services" such as shade, city councilors approved a policy in 2006 not to replace them -- with exemptions given to Hollywood and Sunset boulevards. The city prefers queen palm (Syagrus romanzoffiana), a feather palm that grows more densely and compactly.
Over time, then, L.A's skyline will become less distinctive, with fewer and fewer bundles of fronds floating high above the freeways catching the last warm light of the setting sun. Fifty years from now, the tallest palms in Southern California will be in Orange County and the Inland Empire. Film crews may have to go there to get their "L.A." establishing shots. Or they may just digitally add some high-rise palms.