Plant Morphology with the external features of the plant. Now we can enter into the internal aspects of the plant parts like root, stem and leaf at the cellular and tissue level. The branch of Biology which deals with these aspects is Anatomy . The multicellular body of a flowering plant consists of many structures with varied functions which help the plant in survival and reproduction. Each of these structures, such as stem, leaf, root etc., is composed of many different types of tissues and cells.