The central parenchymatous zone present in the dicot stem.

Explanation

### Step-by-Step Text Solution:

1. **Understanding the Question**: The question asks about the central parenchymatous zone present in the dicot stem. We need to identify what this zone is called and describe its characteristics.

2. **Identifying the Type of Stem**: We recognize that we are dealing with a dicot stem, which is a stem from dicotyledonous plants. These plants typically have two cotyledons.

3. **Central Parenchymatous Zone**: In the structure of a dicot stem, the central parenchymatous zone is referred to as the **medulla** or **pith**.

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