Sunken stomata are found in

Options

A. Leaflets of Cycas
B. Pinus needles
C. Nerium leaves
D. All of these

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks where sunken stomata can be found. Stomata are small openings on the surface of leaves that allow for gas exchange, and their structure can vary based on the plant's environment.

2. **Definition of Sunken Stomata**: Sunken stomata are a modification of normal stomata that are located below the surface of the leaf. This adaptation helps to reduce water loss through transpiration by creating a microenvironment that retains moisture.

3. **Purpose of Sunken Stomata**: The primary function of sunken stomata is to minimize transpiration, which is the loss of water vapor from the plant. This is particularly important for plants that grow in arid or dry environments where water conservation is crucial.

4. **Identifying Xerophytes**: Xerophytes are plants adapted to survive in environments with limited water supply, such as deserts. They have various adaptations, including sunken stomata, to reduce water loss.

5. **Analyzing the Options**:
- **Psychos (Cycas)**: This is a type of cycad that is adapted to dry conditions and has sunken stomata.
- **Pinus (Pine Trees)**: These conifers are also adapted to dry environments and typically have sunken stomata to reduce water loss.
- **Merium Leaves**: This refers to plants that are also adapted to xerophytic conditions and possess sunken stomata.

6. **Conclusion**: Since all the options listed (Psychos, Pinus needles, and Merium leaves) are xerophytes, they all possess sunken stomata to help reduce transpiration. Therefore, the correct answer is "all of these."

**Final Answer**: Sunken stomata are found in all of these: Psychos, Pinus needles, and Merium leaves.

---