One of the most important parts of plants is the stomata. Stoma is the singular form of stomata and it means ‘mouth’. Stomata function is to regulate the process of photosynthesis, transpiration, respiration, etc. Stomata are found on the leaves of plants. They can either be present on both the sides or just on one side of the leaf.
The structure of the stomata consists of a kidney shaped epidermal cell with an opening in the center which is known as a pore. Inner walls of the guard cells face the aperture and are thicker than the outer layers. Guard cells also have large vacuoles. The cells which surround the guard cells are known as subsidiary or accessory cells.
The most important and major function of stomata is the exchange of gases. In simple terms we can say that the plant takes CO2 from the atmosphere and gives out O2 which is utilized by animals and human beings.
Stomata Function in Photosynthesis
Photosynthesis is a process of manufacturing food in the plant with the help of sunlight, carbon dioxide and water. The plant takes carbon dioxide from the atmosphere which is taken through the stomata. The water molecule is broken down into hydrogen and oxygen and the oxygen is then released in the atmosphere as a by product. This oxygen is also released through the stomatal openings. Hence we can say that the medium of gaseous exchange is stomata. This is a medium of cellular respiration in plants. The work which a nose does for us is similar to the stomata in a plant.
Stomata Function in Transpiration
Transpiration is a process of evaporation of water from the surface of the plant. This is done through the stomatal openings. This helps the plant to get cool and also helps in the transfer of minerals and other materials to different parts of the plant. As the plant takes water from the soil, the openings absorb other minerals. But to transfer these minerals to the surface of the plant, the water on the surface of the plant should be evaporated. Once it is evaporated, it will develop pressure which will force the roots to absorb water from the soil and will be transferred to the tips of the plants. The major work of evaporation of water is done by stomata. Go through what is transpiration to get a better idea.
Opening and Closing of Stomata
Apart from the transpiration and photosynthesis process, stomata also have another very important function. This function is to save water loss. This is done by the opening and closing of the stomata. Plants cannot make their food at night. This is because they do not get sunlight which in turn does not open the stomata. As soon as sunlight strikes the plant’s leaf, there is a change in turgor pressure. This forces the guard cells to form a crescent shape and open the pores of the stomata. This makes the pores open and the processes of photosynthesis, transpiration and respiration are continued. But once the sun sets, the guard cells lose the turgor pressure and this results in the closing of the stomata. This opening and closing also depends upon the environmental conditions. In adverse condition such as very high temperature, the stomata closes itself to stop water loss. They sometimes also keep moist air closed inside themselves to prevent the plant’s tissues from freezing in excess cold.