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Stoma density and water lossFeatured science projectScience project video


This science fair project was conducted to compare the relationship between stoma density and loss of water through transpiration. The experiment was performed with large leaves from the elephant ear plant, the money plant (medium size leaves) and ivy (small leaves).


Plants with big leaves have more stomata and lose more water through transpiration.

Scientific Terms

Transpiration, stomata, stoma, photosynthesis, hydrostatic pressure



Transpiration in plants will cause water to be lost from the surface of the leaves, stems, flowers and fruits. The amount of water that is lost from plants through transpiration will depend on the size of the plant, the temperature of the plant, the humidity, amount of light received, wind and the amount of water in the soil.

The leaves of a plant contain a lot of stomata. These stomata consist of a hole called the stoma and guard cells at the sides. The opening in the stomata is used for gas exchange to take place. While some plant species have stomata on both sides of the leaf, most plants only have them at the bottom side of the leaf. The guard cells are used to open and close the stoma. When the stoma is open, carbon dioxide molecules will enter and be used in the photosynthesis process. However, water will also escape from the stoma when it is open.

When the diffusion of water molecules from the leaf surface occurs, the hydrostatic pressure in the upper parts of the plant will be reduced. This will cause water from the roots to flow upwards and carry nutrients from the soil. The flow of water will also help to cool the plants.

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Complexity level:
Project cost ($):
Time required:
1 hour to prepare, 5 days for the science project experiment
Material availability:
Plants may be purchased at a plant nursery.
Safety concerns:

Basic safety requirements