Stomata

The stomata serve a vital function to plants as a whole. They are the structures which allow transpiration to occur, keeping the plant from drying up by promoting water flow. The stomata are small openings on the bottom sides of leaves. These openings lead into the spongy mesophyll, where gas exchange occurs. This gas exchange allows the plant to photosynthesize as well as perform transpiration. In order to prevent excessive water loss in the case of a drought the stomata are bordered by guard cells. When water is plentiful the guard cells fill with water, causing them to open. When water is scarce however, the guard cells lose water and shrink. This shrinkage causes them to close the stomata shut, preventing further water loss of gas exchange.