Meristematic tissue responsible for secondary growth in plants in the cortex region.

Explanation

### Step-by-Step Solution:

1. **Understanding Secondary Growth**:
- Secondary growth refers to the increase in thickness or girth of the plant, primarily occurring in stems and roots. This growth is due to the division of cells in specific meristematic tissues.

2. **Identifying Meristematic Tissues**:
- The meristematic tissues responsible for secondary growth are known as lateral meristems. These include the vascular cambium and cork cambium.

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