Explain the role of tapetum in the formation of pollen-grain wall .

Explanation

**Step-by-Step Solution:**

1. **Definition of Tapetum:**
- The tapetum is the internal layer of the microsporangium (the pollen sac) in flowering plants. It plays a crucial role in the development of pollen grains.

2. **Nutritional Support:**
- One of the primary functions of the tapetum is to provide nutrition to the developing pollen grains. This nutritional support is essential for the growth and maturation of the pollen.

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