_______ give hardness to the seed coat.

Explanation

**Step-by-Step Solution:**

1. **Understanding Seed Coats**: Seed coats are protective layers that surround seeds. They play a crucial role in protecting the seed from physical damage and pathogens.

2. **Importance of Hardness**: The hardness of the seed coat is essential for seed dormancy, which is a state where the seed is inactive and does not germinate until conditions are favorable.

3. **Role of Stone Cells**: The hardness of the seed coat is primarily due to the presence of specialized cells known as stone cells. These cells are a type of sclerenchyma tissue, which is known for providing structural support and rigidity.

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