In which of the following, the growth is sub-apical ?

Options

A. Root
B. Pedicel
C. Shoot
D. Petiole

Explanation

To determine which of the following options exhibits sub-apical growth, we need to analyze the growth patterns of each option: root, shoot, and petiole.

### Step-by-Step Solution:

1. **Understanding Growth Types**:
- Growth in plants can occur at different regions, primarily categorized as apical, sub-apical, lateral, and intercalary growth.
- **Apical Growth**: Occurs at the tips of roots and shoots.
- **Sub-apical Growth**: Occurs just below the apical region.
- **Lateral Growth**: Involves growth from the sides.
- **Intercalary Growth**: Occurs at specific regions along the stem or petiole.

2. **Analyzing the Options**:
- **Roots**:
- Roots have a specific structure called the root cap at their tip, which protects the growing point.
- Below the root cap, the root is divided into three zones:
- Zone of cell division (where new cells are formed),
- Zone of elongation (where cells grow longer),
- Zone of cell maturation (where cells differentiate).
- The growth in roots is primarily sub-apical because it occurs just below the root cap.

- **Shoots**:
- Shoots grow primarily at their tips (apical growth) where the apical meristem is located.
- Therefore, shoots do not exhibit sub-apical growth.

- **Petiole**:
- The petiole (the stalk that attaches the leaf blade to the stem) shows intercalary growth, which occurs at the base of the leaf or between nodes, not sub-apical growth.

3. **Conclusion**:
- Based on the analysis, the only option that exhibits sub-apical growth is the **root**. The growth in roots occurs just below the root cap, making it sub-apical.

### Final Answer:
The correct answer is **root**; in roots, the growth is sub-apical.

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