Study of distribution of stomata in the upper and lower surfaces of leaves


A French naturalist named Julien Joseph Vesque first discovered stomata. He developed a model of stoma formation. Later, two other scientists named Metcalfe and Chalk further developed it. In land plants, scientists have stated that the stomata appear in the middle of the Silurian period, however, the evolution process has very little proof in terms of the fossil records. They are the results of the plants’ algae evolution.

What are Stomata?

Figure 1: Stomata

Stomata can be defined as the most crucial part of the plants that can help in the gaseous exchange between the plant and nature. The stomata are small openings that are present on the epidermis of the leaves. Humans only under a light microscope can observe it. Not only in leaves, but it can also be present on the stems and other parts of the plants. They are thousand of dots that are present on the surface of the leaves.

The main function of the stomata is to participate in the exchange process of CO2 and water that is between plants and nature. It controls everything by the opening and closing of pores on the surface of the leaves. Mainly, it removes the excess water from the plant's body. It helps in taking the carbon dioxide from nature and gives out oxygen and water.

Aim of the Study

This study aims to understand the pattern of the distribution of the stomata on both sides of the leaf surface. It varies on many things, such as monocots and dicots, and species of the plants.


Stomata are tiny pores on the epidermis of the leaves and they can be present in the young shoot of the plants too. They participate in the gas exchange process and balance the water level of the plants. It has different parts and are made of specific cells. The cells are known as the guard cell. It is responsible for the process of checking and regulating the stomata. It means it controls the opening and closing of the stomata.

The process, in which the water releases into nature in the form of vapour, from the stomata, is known as transpiration. Not only that but it also intakes carbon dioxide from nature while releasing oxygen at the same time.

Figure 2: Opening and Closing of Stomata

The availability of the stomata depends on the dicot or monocots, side of the leaves, plant species, etc. It is also found in that places where more light is available. In that case, moisture in the environment matters the most. However, if compared, the upper and the lower surface of the leaves have an equal number of stomata.

Required Materials

This study needs various essential materials and they are-

  • Glass slide

  • Blade

  • Forceps

  • Watch glass

  • Glycerine

  • Needle

  • Brush

  • Compound microscope

  • Distilled water

  • A four o’clock plant

  • Cover slip

  • Dropper


For conducting the experiment, the first step is to take one leaf that needs to be fresh, from 4 o’clock plants. In the next step, some distilled water is to be added to the watch glass. The leaf needs to be slit in an oblique manner. One section from the upper surface of the leaf needs to be peeled with the help of a forceps. This section has to be placed over the watch glass. The second section needs to be peeled from the lower part of the leaf and in the same way it has to be placed over the second watch glass.

Safranin solution needs to be added to both watch glasses with the help of the dropper. Glass slides need to be placed on the top. One rectangular slide needs to be cut from both the peels and a drop of glycerine is added to each slide. With the help of the needle, one cover slip needs to be added on each of the peels then both of the slides need to be placed under the microscope. It will help to count and notice the distribution of the stomata on both sides of the leaf.


Figure 3: Stomata under microscope

The leaf that was taken for the experiment from a 4 o’clock plant shows that the upper epidermis has fewer stomata in comparison with the lower epidermis.


A few things need attention during the experiment. They are-

  • Leaf curling can hamper the experiment and its results

  • Cover slips need to be placed without making air bubbles

  • A brush is essential for transferring the peels from the slides to the watch glass.


Stomata are the most important part of the plant, which can help both, the plant and the environment. It helps the leaf to participate in photosynthesis which helps it produce food, which is the basis of the food cycle. It also helps in maintaining the levels of gas and water.


Q1. How do stomata distribute on the leaf surface?

Ans. The distribution of stomata depends and varies upon many things. Such as, it varies between the monocots and dicots, or depends on the plant species, and can vary between two sides of the leaves.

Q2. Where are the stomata found more?

Ans. The stomata can be found more on the plant's surface which can flourish under higher sunlight or have lower CO2 concentration. Moreover, moisture in the environment is needed.

Q3. Is the stomata distribution even on both sides of the leaf?

Ans. The distribution of stomata in the upper and lower surface of the leaf especially in the case of the dicot leaf is not even. This means the upper and lower surface has an unequal number of stomata on each side.

Q4. What are water stomata?

Ans. Those plants that are inhabited in the humid region have water stomata. It is one kind of tissue presents in the leaves, which secretes water through the pores in the epidermis. Majorly they are located on the leaf margin.

Updated on: 24-Apr-2023

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