The layer formed to the inside of the cork cambium.

Explanation

### Step-by-Step Solution:

1. **Understanding Cork Cambium**: The cork cambium, also known as phallogen, is a type of meristematic tissue that is responsible for the secondary growth in plants. It is located in the outer bark and plays a crucial role in the formation of the periderm.

2. **Components of Periderm**: The periderm consists of three layers:
- **Phelum**: This is the outermost layer formed by the cork cambium. It provides protection to the plant.
- **Phelogen**: This is the cork cambium itself, which is responsible for the production of new cells.
- **Pheloderm**: This is the innermost layer formed inside the cork cambium.
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