Bur Oak (Quercus macrocarpa). If you want a tree that will create a cool lush green cloud over your head, this is the one for you. Its deeply lobed leaves filter a thousand shades of golden green. While oaks have a reputation for slow growth, this species can grow 3-4' a year in Southern California. Its one imperfection is that it is difficult to find. You can order it on-line from Forestfarm nursery in Oregon.