The excretory products of the plants may either be excreted out or may be stored as per the need of the plant. The excess amount of water in the plants can be removed by transpiration while the waste materials may be stored in the cell vacuoles or especially in old xylem vessels such as gum and resin. If it is also stored in the leaves then they fall off later. By the process of diffusion through stomata, the waste products that are obtained at the end of photosynthesis (oxygen) and respiration (carbon dioxide) are released.