Q.Define Guttation.

Guttation is the loss of liquid water (as droplets) from leaf margins/tips through hydathodes, driven by root pressure when transpiration is minimal.

At night, or in conditions of high humidity, transpiration (loss of water as vapour through stomata) is greatly reduced because stomata are closed or the air is nearly saturated with moisture. However, roots continue to actively absorb water and mineral ions from the soil, building up root pressure — a positive pressure that pushes water up through the xylem. With little or no transpiration to 'pull' this water away as vapour, the excess water is instead forced out of the plant in LIQUID form through small, specialised pores at the tips and margins of leaves called hydathodes (structurally modified stomata-like pores connected directly to the xylem vein endings, usually permanently open, unlike ordinary stomata). This process — the exudation of water droplets through hydathodes due to root pressure — is called guttation, and it is commonly observed as tiny drops of water on the tips of grass blades or the leaf margins of plant …