Ans. Plants deposit many metabolic wastes in their bodies as harmless insoluble materials.
1) Calcium oxalate is deposited in the form of crystals in the leaves and stems of many plants e.g. in tomato.
2) In trees which shed their leaves yearly, the calcium oxalate is removed from body during leaf fall.
3) The removal of excretory products is a secondary function of leaf fall. If the leaves are not shed, the calcium oxalate just remains as harmless crystals in the leaves.