You might want to choose a tree that is consistent. Look around the tree and look at several branches and many leaves. Select a few representative leaves. You can find a name for an oak by looking at the leaves and comparing to the pictures. We have pictures of the common tree oaks and the shrubby oaks .
Hybrids often assume a brushy or shrub form.
Before deciding on the name, check the map to see if the matching name you found is attributed to oaks where you found your leaves. Then, compare the acorns to see if they match. And to make sure, read about the habitat and see if that matches. Pavlik, B. M., P. C. Muick and M. Popper 1991. Oaks of California.