State the main function of the following:
Sunken stomata

Explanation

### Step-by-Step Solution:

1. **Understanding Stomata**: Stomata are small pores located on the surface of leaves that facilitate the exchange of gases (like oxygen and carbon dioxide) between the plant and the atmosphere.

2. **Function of Normal Stomata**: Normal stomata allow for gas exchange but also lead to water loss through a process called transpiration. This can be problematic for plants, especially in arid environments.

3. **Introduction to Sunken Stomata**: In response to the challenges of water loss, some plants, particularly those in desert environments, have evolved a special type of stomata known as sunken stomata.

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