Girth of stem increases due to

Options

A. apical meristem
B. lateral meristem
C. intercalary meristem
D. vertical meristem

Explanation

**Step-by-Step Solution:**

1. **Understanding Meristems**: Meristems are specialized tissues in plants where active cell division occurs. They are responsible for the growth and development of the plant.

2. **Types of Meristems**: There are two main types of meristems:
- **Apical Meristem**: Found at the tips (apex) of roots and shoots, responsible for primary growth (elongation).
- **Intercalary Meristem**: Located between mature tissues, helps in the regeneration and repair of the plant after injury.

3. **Primary Growth vs. Secondary Growth**:
- **Primary Growth**: Involves elongation of the plant body, which is facilitated by apical and intercalary meristems.
- **Secondary Growth**: Refers to the increase in girth (thickness) of the stem and roots, which is caused by lateral meristems.

4. **Lateral Meristems**: These are also known as secondary meristems and are responsible for secondary growth. They are cylindrical in shape and contribute to the increase in the diameter of the stem and roots.

5. **Conclusion**: The girth of the stem increases due to the activity of lateral meristems, which are responsible for secondary growth.

**Final Answer**: The girth of the stem increases due to lateral meristems (secondary meristems).

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