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Updated on 25th May, 2023 , 9 min read
Stomata, the tiny openings on the surface of green plants, play a vital role in facilitating the exchange of water and carbon dioxide between the plant and its surrounding atmosphere. When observed under a microscope, these stomata are easily visible. Each individual opening is referred to as a stoma, and they are present in the epidermis of leaves, stems, and other plant organs. The surface of leaves is adorned with thousands of these stomata. The significance of stomata lies in their contribution to crucial plant processes such as transpiration and photosynthesis, which are essential for the plant's survival. These processes are carried out through well-defined structures and procedures. In this comprehensive article, we will delve into the intricacies of stomata, providing detailed information on their structure, types, diagrams, functions, mechanisms, and more.
Stomata are small pores or openings found on the surface of leaves, stems, and other plant organs. They serve as gateways for gas exchange between the plant and its environment, allowing for the intake of carbon dioxide (CO2) and the release of oxygen (O2) and water vapor. Each stoma is surrounded by specialized cells called guard cells, which control the opening and closing of the stomatal pore. The presence of stomata is crucial for the processes of photosynthesis, transpiration, and respiration in plants. These minute structures play a vital role in maintaining the overall health and functioning of plants.
Stomata consist of a kidney-shaped epidermal cell housing a central opening known as a pore. Surrounding the stomata are a pair of specialized parenchymal cells called guard cells. The guard cells play a crucial role in controlling the size of the stomatal opening, thus helping to prevent excessive water loss from the plant. Although the shape of the cells may vary slightly, the overall structure and composition of each stoma pore remain the same, ensuring the proper functioning of the stomata.
A stoma's four vital parts are:
Stomata exhibit different types based on the characteristics of the guard cells and the arrangement of subsidiary cells. From an evolutionary perspective, stomata can be classified into the following four types:
The Dicotyledonous type is another significant type of stomata, which holds diagnostic importance among these classifications.
These various types of stomata exemplify the diversity and adaptations found in different plant groups, highlighting their distinct structural features and functions.
Name |
Description |
Example |
Paracytic or Rubiaceous or Parallel-celled stomata |
Two subsidiary cells are parallel to the longitudinal axis of pore and guard cells.
|
Senna and Coca. |
Diacytic or Caryophyllaceous or Cross-celled Stomata |
The Pores of the stomata remain surrounded by a pair of subsidiary cells whose common wall is at a right angle to the guard cells.
|
Peppermint, Spearmint, Vasaka. |
Anisocytic or Cruciferous or Unequalcelled Stomata |
The stomata remain surrounded by three subsidiary cells, of which one is distinctly smaller than the other two.
|
Belladonna,Datura,Stramonium,Hyoscyamus. Vinca. |
Anomocytic or Ranunculaceous or Irregular-celled Stomata |
The stomata remain surrounded by a limited number of subsidiary cells like the remaining epidermal cells.
|
Buchu, Clove, Digitalis, Lobelia, Phytolacca americana. |
Actinocytic or Radiatedcelled Stomata |
These stomata are surrounded by four or more subsidiary cells, elongated radially to the stomata.
|
Members of Ebenaceae. |
Stomata serve several important functions in plants, including:
The mechanism of stomata involves the coordinated actions of specialized cells, primarily the guard cells, in response to various internal and external factors. Here is a breakdown of the mechanism:
The mechanism of stomata is a dynamic process that responds to changes in environmental conditions and internal plant signals. This regulation ensures optimal gas exchange, water conservation, and overall plant health and survival.
Stomatal transpiration is the process of water vapor loss from plants through the stomata, which are small openings on the leaf surface. It plays a crucial role in plant water regulation, gas exchange, and cooling. Stomata are opened to allow gas exchange and transpiration, releasing water vapor into the atmosphere. Factors such as light, temperature, humidity, and plant water status influence the rate of stomatal transpiration. It is essential for plant functioning but can be regulated to prevent excessive water loss in unfavorable conditions.
The stomata open and close in response to various internal and external factors. Here's a brief explanation of the process:
Opening of Stomata:
Closing of Stomata:
The opening and closing of stomata are dynamic processes that allow for gas exchange, regulate water loss, and respond to changing environmental conditions, ensuring the optimal functioning and survival of plants.
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By - Nikita Parmar 2024-09-06 10:59:22 , 6 min readStomata are tiny openings found on the surface of plant leaves and stems. They consist of two specialized cells called guard cells, which surround a pore known as the stomatal pore.
Stomata play a crucial role in the exchange of gases, allowing plants to take in carbon dioxide (CO2) for photosynthesis and release oxygen (O2) as a byproduct. They also regulate water vapor loss through transpiration.
Each stomatal pore is flanked by two guard cells. These cells possess a unique kidney or bean shape. When the guard cells are turgid (swollen with water), they create an opening, allowing gas exchange to occur. When they become flaccid, the opening closes.
The kidney or bean shape of guard cells allows them to bend and change shape, which facilitates the opening and closing of stomata. This shape change is primarily influenced by the movement of water and ions across the guard cell membranes.
The opening and closing of stomata are regulated by changes in turgor pressure within the guard cells. When guard cells accumulate water, they become turgid and create an opening. Loss of water causes them to become flaccid, closing the stomatal pore.
Various factors affect stomatal opening and closing, including light intensity, carbon dioxide concentration, humidity, temperature, and plant hormones such as abscisic acid (ABA). These factors help plants optimize their gas exchange and water balance.
Stomata have specialized structures that help reduce water loss. They are typically more abundant on the lower surface of leaves, where they are sheltered from direct sunlight and wind. Additionally, the presence of a waxy cuticle and subsidiary cells aid in minimizing water loss.
No, stomata can vary in size and density depending on the plant species and environmental conditions. Some plants may have larger stomata for efficient gas exchange, while others may have smaller stomata to minimize water loss.
Yes, stomata can be found on plant stems, particularly in species that have evolved to carry out photosynthesis through their stems. These stomata on stems serve the same purpose of gas exchange and regulation of water loss.
While stomata are commonly found in most land plants, some specialized plants, such as aquatic plants or plants with thick cuticles, may have reduced or modified stomata. However, the majority of plants rely on stomata for gas exchange and transpiration.