The leaf is a miracle in design in many ways. The leaf is made up of many organelles and functions. The outer layer of the leaf is the epidermis which contains the lower and upper epidermis. The upper epidermis produces a wax layer called the cuticle which is a waterproof barrier to prevent excessive evaporation. The upper epidermis cells have no chloroplasts so light passes through them easily. The palisade mesophyll where 80 % of photosynthesis occurs. The palisade cells have many chloroplasts in their cytoplasm and the box-like shape of these cells makes sure that they are tightly packed together. The spongy mesophyll have large spaces which, are linked to the stomata on the lower surface. The spongy mesophyll cells contain chloroplasts which, also makes this a site for photosynthesis.