What term is used to describe the covering of pollen grains that has characteristic sculpturing?

Explanation

**Step-by-Step Solution:**

1. **Understanding Pollen Grain Structure**: Pollen grains are the male gametophytes in flowering plants and have a specific structure that includes two layers.

2. **Identifying the Layers**: The two layers of a pollen grain are:
- **Entine**: This is the inner layer of the pollen grain.
- **Exine**: This is the outer layer of the pollen grain.

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