Mention the most significant role of phellogen.

Explanation

### Step-by-Step Solution:

1. **Definition of Phellogen**:
- Phellogen, also known as cork cambium, is a type of meristematic tissue in plants. It plays a crucial role in the growth and development of the plant.

2. **Function of Phellogen**:
- The most significant role of phellogen is to facilitate the formation of the periderm, which is the protective covering of stems, shoots, and roots in plants.

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