Stomata are tiny pores on the surface of leaves, stems, and other plant organs that allow for the exchange of gases between the plant and its environment. The primary function of stomata is to regulate the entry of carbon dioxide (CO2) into the plant and the exit of oxygen (O2) and water vapor (H2O) from the plant.
During photosynthesis, plants use CO2, water (H2O), and sunlight to produce glucose (sugar) and oxygen (O2). The CO2 required for photosynthesis enters the plant through the stomata. At the same time, water vapor and oxygen produced by photosynthesis exit the plant through the stomata.
The opening and closing of stomata is regulated by guard cells, which are specialized cells that surround the stomatal pore. The guard cells control the size of the stomatal pore by changing their shape, which in turn regulates the rate of gas exchange. When the plant needs more CO2 for photosynthesis, the guard cells open the stomata wider to allow more CO2 to enter. When the plant needs to conserve water, the guard cells close the stomata to reduce water loss through transpiration.