"A lot of the edible stuff is derived from indigenous cultures, but most of ours are gone. And most of the information on what was used has been lost. So that knowledge is not readily available. The kinds of places where you would find that information would be in scientific texts."
Poison oak is an example of a nonedible plant that Rebman uses to show how easily one can be confused by the similar-looking plants. "There's a lot of other things like it that are not poisonous but are native and have the three leaflets. We might think they're poisonous because of how they look, but they're not."
Just how diverse is San Diego's plant life? Besides having the most diverse terrain of any county in the United States, San Diego is the most diverse county in native plants as well. "Because of this mild climate, we can grow a lot of tropical things like fruits. Guavas and papayas can actually grow in our yards because we don't get the freezes. We have to be at the top in our ability to grow things that are edible, as far as horticulture is concerned. I'm not a horticulturist; I'm more interested in plant taxonomy. But the percentage of plants that are edible is going to be a lot higher here than in most other places. But that cuts both ways -- we might also have the highest percentage of poisonous plants! I can't say that for sure, but it's a possibility."
Next to Rebman's office on the top floor of the old section of the museum is the San Diego botanist's holy of holies: The Synoptic Collection, a vast room filled with sample specimens of virtually every native plant in San Diego County. Some of the specimens date back to the 1920s. As he opens one of the lockers, Rebman finds a file with samples of wild carrot from 1938. He opens another file with a sample of hemlock. To the untrained eye, they look identical. "These are both white and have a flower. When dissected, they look a lot alike. You can see the similarity in the leaves. The wild carrot is not always big like this." He pulls out a sample with smaller flowers.
Pulling some more files, Rebman proffers a flattened-looking cactus with its fruit looking like an exploded prune. The sample is dated from 1939, labeled "Mission Prickly Pear." "This is edible as well. You'll see them getting those bright red flowers on them. The fruit has been cut and splayed. A lot of people refer to them as 'Indian figs.' This comes from a higher elevation, but you can see some of the red is still in there. It is very pulpy when fresh." He opens another file with a similar, thinner-looking sample. "Here's another prickly pear species, and it's edible as well. It's not a native plant, but it ended up in a lot of our canyons. People just kind of threw a pad over the fence, and it soon became a forest."
Probably no park in San Diego offers as much horticultural diversity as Balboa Park, but using the park as a source for food would not only taste bad, it would also be illegal. Michael Ruiz, the senior park ranger at Balboa Park, says that plant- and seed-gathering permits are issued rarely. "We do have them, but it's very strict. It would be primarily for entities like the Natural History Museum, who would use it for educational or research purposes. We just don't want anyone coming in here and gathering plants. What happens is that they gather them for their own profit or to save a trip to the nursery to buy cactus. We don't set the fines for that, and they change quite often. That's established by the courts. If a citation is issued, then the fine is established by the judge."
Plant life is not the only wild urban food source. Most of the local species of rabbits, gophers, rats, and pigeons are edible, but Rebman does not suggest anyone satiate their appetite by hunting in the city. "Don't ever think I suggested any of that! You could eat them if you were really desperate, but I don't recommend it."