Suppose you have a small rose plant growing in a pot. How would you demonstrate transpiration in it ?
Initially the rose plants should be watered regularly to raise the moisture content not only in the soil also in the hydathodes of the leaves.
Now cover the plant with a polythene cover and tie up its open ends.
The whole set up is left in an external environment under the presence of sunlight.
After a period of time, you will notice the presence of water droplets inside the bag.