The leaf is a lateral part of plants that performs the most important functions of air supply and gas exchange. The possibility of their implementation is associated with the structural features of the sheet, one of which is stomata. With their help, the plant breathes and evaporates water. What is stomata, what are the features of their structure and organization, we will describe in detail in our article.
Plant respiration and photosynthesis
All living organisms, including plants, are capable of breathing. This well-known fact is a prerequisite for their existence. Its essence is the absorption of oxygen, the oxidation of organic substances and the release of carbon dioxide. But the planetary significance of plants lies in the implementation of the inverse process - photosynthesis. In its course, carbon dioxide is absorbed, and the oxygen needed by all living things is released. Plants are able to carry out these two processes simultaneously with different intensities, largely due to the activity of stomata located on the surface of the leaf.
Stomata structure
What is stomata? These are peculiar pores located in the integumentary tissue of plants called the peel. Stomata are paired cells of predominantly bean-shaped form. Their walls are unevenly thickened in different places. Between the cells of the stomata is the stomatal gap. Through it, various gaseous substances are released into the cells of plants and outward. Binary stomata cells are able to change their shape, as a result of which the size of the gap between them can increase or decrease. As a result of this, the gas exchange intensity in the plant is regulated.
Features of the functioning of stomata
If we understand what stomata is, then here's how they work and what it depends on, we still have to find out. Trailing cells are able to change their shape depending on the amount of water. If there is a lot of this substance in the plant, they swell, increase in size and move away from each other. The stomatal gap in this case, of course, increases. The gas exchange process becomes more intense. Excess water exits through the gap, evaporates, and the plant does not overheat during the hot season.
Transpiration is most intense as well, provided that the temperature rises and the wind increases. In the opposite case, when there is insufficient moisture, the mechanism of action of the trailing cells is different. They are tightly adjacent to each other, while the stomatal gap simply disappears, which impedes the process of evaporation of water. As a result, the plant does not lose moisture in the absence of moisture.
Stomata location
As already mentioned, stomata are the structures of living integumentary tissue of plants. It is called a peel. The stomata of plants are located, in most cases, on the underside of the leaf. This is a kind of protection against direct sunlight. Also, the supply of water in plant cells is better preserved. But not all leaves are horizontal. For example, in irises, they grow vertically. Therefore, stomata are distributed on all sides of the leaves.
The situation is different with aquatic plants. The lower part of their leaves cannot contain stomata. After all, they are completely immersed in water, which means they will not be able to carry out their functions. The stomata of such plants are located on the surface of the leaf blade. Their number is quite large, since there are up to several tens of thousands of such formations on one square centimeter of a sheet.
Stomataless plants
And some plants lack stomata. For example, the leaves of the elodea are completely immersed in water, therefore they cannot contain them. And even if the stomata would have been there, the implementation of their function would have been simply impossible. The thing is that water enters the cracks, preventing the gas exchange process from being carried out.
The value of stomata
The stomata are located in the integumentary tissue, therefore their main function is the body's metabolism with the environment. One of them is water, the evaporation process of which is called transpiration. Its implementation is very important so that the plants do not overheat in the hot season, because this can lead to their death. When evaporation is undesirable, stomata practically stop transpiration, thereby retaining the necessary moisture.
But gymnosperms have a special structure of stomata. They are clogged with special resin during the winter. Therefore, all representatives of this department of plants are evergreen. They do not need to dump foliage to protect themselves from the loss of excess moisture in the winter. In contrast, all angiosperms during this period retain only the shoot and root as viable. But their leaves fall off so as not to lose the supply of water for the winter. Therefore, the Christmas tree "in winter and summer in one color."
What are stomata, how they are arranged and carry out their functions, we have examined in sufficient detail. However, it is worth mentioning that, in addition to transpiration, they also serve as a specialized device for the supply of oxygen, so that the process of respiration and the supply of carbon dioxide for photosynthesis are possible. In addition, stomata are able to control the intensity of all these processes, which depends on external factors, and is manifested in the ability to adapt all living organisms to rapidly changing environmental conditions.
So, in the integumentary tissue of the leaf there are specialized formations called stomata. They consist of binary closure cells and a gap between them. Thanks to the activity of this structure, the most important processes of water evaporation, photosynthesis and respiration are carried out in the plant body.