Tree foliage is the LEAVES of a tree. It is the main source of food for the tree, as it uses photosynthesis to convert sunlight into energy. Tree foliage also provides shade and protection from the elements. The term 'LEAVES' is used to describe the foliage of a tree, as it is composed of many small, thin structures that are attached to the branches. LEAVES come in a variety of shapes, sizes, and colors, and can be either deciduous or evergreen.