Identifying trees can be trickier in the winter, but many types of oaks, such as the white oak, hold onto their leaves in the colder months—even if the leaves turn brown and die. If the oak loses its leaves, you can look for other clues, like the appearance of the bark or the shape of the buds at the ends of branches. You might also be able to find acorns still scattered around the base of the tree or clinging to some of the branches.