Formations on the stem of a rounded shape participating in the process of respiration.

Plant respiration process

Plants breathe constantly at any time of the day or night. The essence of this process is that during breathing carbon dioxide, water and a certain amount of energy are released. All parts of the plant have the ability to breathe, but with different activity. The flowers breathe more intensively, but the leaves also breathe more strongly than the stems. The leaf plate plays an important role in the respiration process:

• oxygen is absorbed;
• carbon dioxide is released;
• nutrients are consumed;
• water is released;
• heat is generated.

Leaf skin and its structure

The upper and lower parts of the leaf are covered with a thin transparent skin. It prevents damage and drying of the sheet plate. The skin tends to transmit light well so that photosynthetic cells can do their job. The skin belongs to the integumentary tissues. On the surface of the leaf there is a wax-like cuticle secreted by the cells of the skin. It protects the sheet from excess evaporation. The skin of the leaf is made up of living cells. They are colorless, rather large, tightly adjacent to each other.

Stomatal apparatus

Next to colorless cells, smaller ones coexist with chloroplasts. They are arranged in pairs and participate in the formation of the stomatal apparatus. Green cells have the ability to change their shape. In the process of changing the shape, the appearance or disappearance of the opening of the stomatal fissure is observed. Therefore, it is customary to call them guard cells. They are formed by thicker cells on the side of the stomatal gap and thin walls on the other side. This structure plays an important role in the work of the stomatal apparatus. Air chambers are located under the stomata, which serve to evaporate water and gas exchange. If the air around is dry and hot, water evaporates quickly. Then the stomatal gap is closed.
In some plants, stomata are on both sides of the leaf, in others, on the lower part of the leaf in the shade. Stomata in the aquatic environment cannot work. Therefore, leaves that have taken their place in the aquatic environment and float on the surface have the stomata at the top. There are no stomata at all on underwater plants.