Innermost layer of pollen sac which functions as a nutritive layer is

Options

A. Endothecium
B. Tapetum
C. Endothelium
D. Intine.

Answer

To solve the question regarding the innermost layer of the pollen sac that functions as a nutritive layer, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Structure of Pollen Sac**:
- The pollen sac consists of multiple layers. It is essential to identify these layers to determine which one serves the purpose of nourishment.

2. **Identifying the Layers**:
- The layers of the pollen sac include:
- Epidermis (outermost layer)
- Endothecium (second layer)
- Middle layer
- Tapetum (innermost layer)

3. **Function of Each Layer**:
- The epidermis serves as a protective outer layer.
- The endothecium provides structural support.
- The middle layer has a supportive role but is not primarily nutritive.
- The tapetum, however, is known for its role in providing nutrition to the developing pollen grains.

4. **Conclusion**:
- Since the tapetum is identified as the innermost layer of the pollen sac that functions as a nutritive layer, we conclude that the correct answer to the question is **tapetum**.

### Final Answer:
The innermost layer of the pollen sac which functions as a nutritive layer is **tapetum**.

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