What is the one palm tree native to the San Diego area?

The California Fan Palm is native to San Diego County. All of the other types of palm trees, e.g. date palms and royal palms, have been artificially planted here by man.
Here’s a little history about the California Fan Palm.
The California Fan Palm was an important resource for the Cahuilla Indians of Southern California, who called it maul. They used it for food, especially the fruit/nut which they ground up as flour or made into a mush. They also soaked the fruits to produce a sweet beverage and made jelly from the fruit. Trees produced a dozen or so such date clusters at 5-20 lbs. each.
The spongy pith in the center was sometimes boiled and eaten and was called maul pasun or “heart of the palm.” The Fan Palm was also used for construction (fronds for roof thatch), and leaves were stripped and used in various weaving applications.
The hard seeds that fell after fruit pulp dried were the preferred fill for gourd rattles and were better than stones or other seeds. The Desert Cahuilla also preferred the Fan Palm for making sandals and certain fire making tools as well as tinder were made from this palm.