Name the tissue that forms the hard covering of seeds and nuts.

Explanation

**Step-by-Step Solution:**

1. **Identify the Types of Plant Tissues**: Understand that plant tissues can be categorized into three main types: Parenchyma, Collenchyma, and Sclerenchyma.

2. **Analyze the Characteristics of Each Tissue**:
- **Parenchyma**: This tissue is involved in functions like photosynthesis and storage. It consists of living cells and is not hard.
- **Collenchyma**: This tissue provides support and flexibility to plants. It consists of living cells that are thicker at the corners but still not hard.
- **Sclerenchyma**: This tissue is known for its hardness and rigidity. It consists of dead cells that are usually filled with lignin, which makes them stiff.
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