GUARD CELLS are specific leaf structures that regulate the opening and closing of stomata.
These cells are produced in pairs and a stomata pore is formed between them. Swollen guard cells lead to the opening stomata while shrunken guard cells lead to the closing of the stomata.
The swelling and shrinking of the guard cells are caused by the changes of its turgor pressure, which are controlled by the movements of huge quantities of sugar and ions moving in and out of the guard cells.
