I'm glad to know I'm living in a cultural desert. Looking at both the bands and the visual artists out here, we must have different usages of the word "desert" :)
He'll learn soon enough that it's the desert where 90% of America's culture comes from. It's hard to understand without living there.
Los Angeles proper; downtown and the surrounding areas, have a great climate because of the onshore breeze that comes in through Santa Monica. The indigenous foliage (what's left of it) there and up into the foothills is quite varied, and with everything the inhabitants have planted over the years, can be quite dense in some areas (largely supported by water from elsewhere in the state).
The extended areas as well, Angeles National Forest and the San Gabriel Mountains, can be comparable in density and recreation to forests across the nation.