In dry arid condition, the leaves of some monocots,like grasses curls inwards to reduce transpiration. This is due to the presence of

Options

A. parallel venation
B. bulliform cells
C. large xylem cavities
D. thick cuticles

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks why the leaves of some monocots, like grasses, curl inwards under dry arid conditions to reduce transpiration.

2. **Identifying Key Terms**:
- **Transpiration**: This is the process through which plants lose water vapor from their leaves, primarily through small openings called stomata.
- **Monocots**: These are a group of flowering plants that have one embryonic seed leaf or cotyledon. Examples include grasses.

3. **Analyzing the Options**:
- **Parallel Venation**: This refers to the arrangement of veins in the leaves of monocots, which does not directly relate to the curling of leaves to reduce transpiration.
- **Buliform Cells**: These are specialized cells found in the epidermis of monocot leaves that can change shape based on water availability. When water is abundant, they remain turgid, keeping the leaves flat. When water is scarce, they lose turgor pressure, causing the leaves to curl inwards, thereby reducing the surface area exposed to the air and minimizing water loss.
- **Large Psyllium Cavities**: This term does not relate to leaf structure or transpiration in the context of the question.
- **Thick Cuticles**: While a thick cuticle can help reduce water loss, it does not explain the curling mechanism specifically.

4. **Conclusion**: The correct answer is **B, Buliform Cells**. These cells play a crucial role in the leaf's ability to curl and thus reduce transpiration in dry conditions.