Keep the plant in the dark for several days. Then select two leaves and coat their upper surfaces heavily with petroleum jelly. Select two more leaves and heavily coat their under surface with petroleum jelly. Place the plant in a sunny window for a week and observe. The leaves coated on the underside will appear to die as time goes on.
Transpiration occurs in leaves after being separated from the tree.
Plants absorb water from the earth. Water moves up from the roots, through vessels and tracheids, to reach the leaves. This water loss through the stomata is called transpiration. A plant that runs out of water in the soil will transpire itself to death. Place the sandwich bag over one leaf of the plant.