Describe the process of transpiration. The stomata close at night or when the plant is water stressed. This release of H2O is called transpiration.
Water vapor moves freely from the leaf through the open stomata.
Select 3 coleus or geranium plants, making sure the foliage is dry, and the soil is well watered. Place a clear dry plastic bag over each, and tie them off around the base of the stalk, place one plant in the sun, another in an enclosed or dark area and the other in open shade. Students should record observations, after one half hour, after another half hour, then again in 24 hours.