The loss or excretion of water in the form of liquid droplets from the leaves and other parts of uninjured or intact plant is called guttation. It was first studied by Bergerstein in 1887. All plants do not show guttation. It is restricted to about 345 genera of herbaceous and some woody plants. Common examples are garden nasturtium, oat and other cereals, balsam, tomato, cucurbits. Guttation takes place through special structures called hydathodes. They are usually found on the margins and tips of the leaves.