As a recent first time visitor to California, from Australia, the abundant eucalyptus and jacarandas were a major surprise. Of course the palm-lined strips in Santa Barbara and Los Angeles were expected, though still impressive - I hadn't thought to lump those in with the other immigrants.
Thankfully we also got up to Muir Woods (just north of San Francisco) for a taste of the pre-European flora. Looks to be an interesting book, weaving the history of the state through the botanical angle.
I'm Australian, lived in LA for a decade or so .. and my trips around the Griffith Park area always led me to a particular grove of eucalypts and jacaranda that always reminded me, very much, of home. There are parts of that park that could be Australia, imho .. minus the snakes, but plus coyotes and cougars ..
Native Los Angelope, when I visited Australia there were definitely parts where I was like, this looks like home! I think it was just the eucalyptus, but it was pretty sweet.
Many years ago I worked on a book about the riverfront homes of Brisbane - I was surprised to learn that the two most conspicuously flowering trees (the other being the Poinciana, from Madagascar) were just as imported as the design of the 'Queenslander' style house (which arose in colonial India).
"Thankfully we also got up to Muir Woods (just north of San Francisco) for a taste of the pre-European flora" -Its not like the entire ecosystem of California is palm trees. The way you make it sound, it sounds pretentious.
In my seaside Mediterranean town many oaks have been cut down and replaced with palms to give the town a more glamorous look.
Now in those areas there is no shade and during summer they are deserted, the only moving objects are cars. Some grass and palms among asphalt and concrete are simply not a good heat moderator. It looks nice on a postcard though ^^.
On the topic of non-native palms - I only recently learned that most of the 'palms' that are a surprising sight in the UK - eg in Plockton in the north of Scotland
https://en.wikipedia.org/wiki/Plockton
... aren't palms at all, but Cabbage Trees, native to New Zealand (https://en.wikipedia.org/wiki/Cordyline_australis) and they're nothing to do with cabbage either. Probably not news to gardeners and botanists but I'd always wondered how they got there.