Water accumulates in the skin cells of ice plants and takes the form of a sac. In winter this water turns into ice. For example, Mesembrayanthemum crystallinum.

(i) Water passes through the hydathode in liquid form.
(ii) There is a water chamber below it. Water accumulates there.
(iii) Hydathodes are more active at night than during the day.
(iv) Hydathodes cause water droplets to appear on leaf edges in the morning.
(v) Salts are released during water evaporation.
(vi) Water excretion is high when perspiration is low.

The cells that make up the hydathode are called epithems. Aqueducts are made up of a bunch of living cells. Cells are watery and have intercellular spaces. The cells do not have chloroplasts. Each hydathode has one or more pores. Its pore is structurally similar to a leaf pore. But somewhat large in size and unable to move. It consists of one or more chambers. The chambers open into windpipe or trachea.

The pores located along the edges of plant leaves through which water is released in liquid form are called hydathodes. The release of water in liquid form is known as gation or water excretion or water drinking. Hydathodes are more active at night than during the day. Hydathodes are located along the edges of plant leaves. That’s why in the morning water is seen on the edges of the leaves. Hydathodes are present in plants like grasses, squash, tomato, saffron, strawberry, primula, rose, balsam, Ranunculus fluitans, Campanula rotundifolia. Hydathods named Esau in 1965.

(i) In the process of photosynthesis, the raw material for making food, carbon dioxide, enters the cell through the stomata. Sugars are produced from carbon dioxide. Plants with more leaves have more stomata. Due to this, the supply of carbon dioxide increases and food production increases.
(ii) Water is an important raw material in the process of photosynthesis. In the transpiration process, excess water is released through the stomata in the evapotranspiration. As a result water flow is created and water enters different cells. This water is used in the process of photosynthesis. (iii) After making food in the process of photosynthesis, oxygen released as a by-product escapes through the stomata. Oxygen is an essential element in photosynthesis. It reduces the rate of photosynthesis. Food production is accelerated when oxygen escapes through the stomata.
(iv) Each stomata contains two guard cells. The guard cell contains a large number of chloroplasts. This chloroplast produces food in the process of photosynthesis.
(v) Green accessory cells surround the stomata. Chloroplasts of accessory cells take part in the process of photosynthesis to make food.

(i) Photosynthesis: The biochemical process by which green plants produce sugary food by chemically combining water and carbon dioxide with the help of chlorophyll in the presence of sunlight and releasing oxygen as a by-product is called photosynthesis. Carbon dioxide needed for photosynthesis enters the cell through the stomata. Carbon dioxide reacts with water to form sugars and release oxygen as a byproduct. Oxygen is released out of the cell through the stomata. Therefore, stomata play an important role in carrying out the process of photosynthesis.
(ii) Respiration : The biochemical process in which respired matter is completely oxidized in the presence of free oxygen to produce water, CO2 and energy is called respiration. Oxygen required for plant growth enters the cells through the stomata. Oxygen reacts with oxygen to produce water, CO2 and energy. The carbon dioxide produced is released out of the cell through the stomata. Therefore, stomata play an important role in carrying out the reproductive process.
(iii) Transpiration: The process by which the excess water absorbed by the roots of the plant evaporates through the stomata is called transpiration. Green plants use only 1-2% of the water absorbed by their roots. The remaining 98-99% of water is useless. Excess water is released by evaporation through the stomata. Therefore, stomata play an important role in carrying out the process of respiration.
(iv) Temperature regulation: A lot of heat is generated as a result of various biological processes in the plant body. During respiration, heat is released through the stomata. If the heat wasn’t released outside, the plant would burn to death.
(v) Gaseous exchange: It involves the exchange of gaseous substances or O2 and CO2.
(vi) Opening and closing of stomata : Guard cells control the opening and closing of stomata.
(vii) Synthesis and storage of organic food: Glucose is synthesized in the guard cells and temporarily stored as glucose.

The leaf pores are hidden deep in the skin. This is called hidden or submerged stomata. The stomata are open during the day and closed at night. However, the stomata of Patharkuchi plants are closed during the day and open during the night. The plant’s stomata are fully open from 10-11 am and 1-3 pm.

There is a large air-filled cavity below the stomata. It is called substomatal cavity. This chamber is also known as air cavity or respiratory cavity.

There are some special types of parenchyma cells surrounding the stoma. These are called accessory cells. Each stomata with accessory cells is called a stomatal complex. Some plants do not have accessory cells. Like- Pumpkin, Cucumber, Orchid etc.

Stomata are covered by two crescent-shaped cells. It is called Rakshikosh. Each guard cell contains cytoplasm, chloroplasts, mitochondria, cytoplasm and a large nucleus. The guard cell has two walls. Outer wall and inner wall. The inner wall is thick and inelastic. But the outer wall is thin, semipermeable and elastic. Guard cells are covered by 2-4 epidermal cells. It controls the opening and closing of stomata.