When it comes to the planting, care, and maintenance of trees, it can be very important to correctly identify the type of tree you are working with. There are numerous resources available to help identify trees.
“Peterson Field Guide to Western Trees” by George A. Petrides and Olivia Petrides
“A Californian’s Guide to the Trees Among Us” by Matt Ritter
“The Sibley Guide to Trees” by David Allen Sibley
“Trees of Western North America” by Richard Spellenberg, Christopher J. Earle, and Gil Nelson