Movement of Water Through the Stomata

Stomata are pores in the leaves caused by the curvature of adjacent guard cells.When guard cells become turgid the thinner outer walls stretch more than the thicker inner walls.This creates a bowed shape that creates a pore between the guard cells through which gases can diffuse.Water evaporates from the mesophyll cells into the air spaces creating a water potential gradient between the air spaces and external environment.Water diffuses down the potential gradient in the air spaces. Water vapour diffuses out of the leaf through the stomata into the external environment.