What is the commerical source of cork ? How is it formed in the plant ?

Explanation

### Step-by-Step Solution

1. **Identify the Commercial Source of Cork**:
- The commercial source of cork is the cork tissue obtained from the plant known as **Quercus suber**, commonly referred to as **cork oak**.

2. **Understand the Formation of Cork in Plants**:
- Cork is formed by specific types of cells in the plant, primarily from the **cambium** or **phellogen** cells.

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