The cells which help in rolling and unrolling of leaf lamina in grasses are

Options

A. complementary cells
B. bulliform cells
C. passage cells
D. companion cells

Answer

### Step-by-Step Solution:

1. **Identify the Question**: The question asks for the type of cells that assist in the rolling and unrolling of leaf lamina in grasses.

2. **Review the Options**: The options provided are:
- Complementary cells
- Buliform cells
- Passive cells
- Companion cells

3. **Understand the Function of Each Cell Type**:
- **Complementary cells**: These are not primarily involved in the rolling and unrolling of leaves.
- **Buliform cells**: These are large epidermal cells that play a crucial role in the movement of the leaf lamina.
- **Passive cells**: These do not have a specific function related to leaf movement.
- **Companion cells**: These are associated with phloem and are not involved in leaf movement.

4. **Focus on Buliform Cells**: Buliform cells, also known as motor cells, are located on the upper surface (adaxial surface) of the leaf. They are hygroscopic, meaning they can absorb water.

5. **Explain the Mechanism**:
- Under dry conditions, buliform cells lose water, causing them to shrink and leading the leaf lamina to roll up. This helps reduce water loss.
- Conversely, when water is available, these cells absorb water, swell, and cause the leaf lamina to unroll, allowing for maximum photosynthesis and gas exchange.

6. **Conclusion**: Based on the function and location of the cells, the correct answer is **Buliform cells**.

### Final Answer:
The cells which help in rolling and unrolling of leaf lamina in grasses are **Buliform cells**.

---