The lower epidermis of a leaf generally has more stomata.
Here's why:
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Stomata and Gas Exchange: Stomata are tiny pores on the leaf surface that facilitate gas exchange (carbon dioxide intake and oxygen release) necessary for photosynthesis. They also allow water to escape through transpiration.
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Location and Environment: While stomata can be found on both the upper and lower epidermis of a leaf, their distribution is often uneven. The lower epidermis, being on the underside of the leaf, is typically more shaded.
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Reduced Water Loss: Having more stomata on the underside reduces the direct exposure to sunlight and wind, which minimizes excessive water loss through transpiration. This is crucial for plant survival, especially in drier environments.
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Example: Think of a plant in a hot, sunny environment. If the upper epidermis had significantly more stomata, it would lose water at a much faster rate due to direct sunlight exposure. The distribution of more stomata on the lower surface helps to conserve water.
In summary, while stomata are present on both leaf surfaces, the lower epidermis usually has a higher concentration to optimize gas exchange while minimizing water loss.
