secondary growth in dicot plants is mediated by

Options

A. cork cambium
B. vascular cambium
C. wound cambium
D. both A and B

Answer

**Step-by-Step Solution:**

1. **Understanding Secondary Growth**: Secondary growth in dicot plants refers to the increase in girth or thickness of the plant stems and roots. This growth is primarily due to the activity of certain types of cambium.

2. **Identifying the Types of Cambium**: In dicot plants, two main types of cambium are involved in secondary growth:
- **Vascular Cambium**: This cambium is responsible for the formation of secondary vascular tissues (xylem and phloem) and parenchyma. It is formed by the joining of intrafascicular and interfascicular cambia.
- **Cork Cambium**: This cambium is responsible for producing cork (outer bark) and secondary cortex. It arises from the de-differentiation of cortical tissues and undergoes periclinal divisions.

3. **Role of Vascular Cambium**: The vascular cambium divides periclinally, which means it divides parallel to the surface of the plant. This division leads to the production of secondary xylem (wood) towards the inside and secondary phloem towards the outside.

4. **Role of Cork Cambium**: The cork cambium also divides periclinally, producing cork cells towards the outer side and secondary cortex towards the inner side. This is essential for protecting the plant and reducing water loss.

5. **Wound Cambium**: While the wound cambium is involved in healing and repair of wounds, it is not primarily responsible for the regular secondary growth in dicots. It forms in response to injury.

6. **Conclusion**: Since both vascular cambium and cork cambium contribute to secondary growth in dicot plants, the correct answer to the question is that secondary growth is mediated by both A (cork cambium) and B (vascular cambium).

**Final Answer**: Secondary growth in dicot plants is mediated by both A (cork cambium) and B (vascular cambium).

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