Tapetum is

Options

A. Parietal in origin
B. Inner most wall layer of pollen sac
C. Nutritive and provides wall material to pollen grains
D. All of above.

Answer

**Step-by-Step Solution:**

1. **Understanding Tapetum**: The tapetum is a layer found within the anther of flowering plants. It is crucial for the development of pollen grains.

2. **Anther Structure**: The anther wall consists of four layers:
- **Epidermis**: The outermost protective layer.
- **Endothelium**: The layer beneath the epidermis.
- **Middle Layers**: Two to three layers that provide additional support and protection.
- **Tapetum**: The innermost layer that surrounds the pollen sac.

3. **Characteristics of Tapetum**:
- The cells of the tapetum have dense cytoplasm and often contain more than one nucleus.
- This dense cytoplasm is essential for nourishing the developing pollen grains.

4. **Function of Tapetum**:
- The tapetum plays a vital role in providing nutrients to the developing pollen grains.
- It also secretes structures known as orbicules (or eubish bodies), which are involved in the formation of the pollen grain's outer wall layer, made up of sporopollenin.

5. **Evaluating Options**:
- **Option 1**: "Parietal in origin" - This is correct as the tapetum is derived from the anther wall, which is part of the male reproductive structure.
- **Option 2**: "Innermost wall layer of pollen sac" - This is also correct since the tapetum is indeed the innermost layer of the anther wall.
- **Option 3**: "Nutritive and provide wall material to pollen grains" - This is correct as well, since the tapetum nourishes pollen grains and contributes to their wall structure.
- **Option 4**: "Olive turbine" - This option is irrelevant and incorrect.

6. **Conclusion**: All the relevant options about the tapetum are correct. Therefore, the tapetum is nutritive, provides wall material to pollen grains, and is the innermost layer of the pollen sac.

**Final Answer**: Tapetum is all of the above.

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