When secondary growth is initiated in dicot stem, what will happen first?

Options

A. The cells of cambium divide periclinally to form xylem mother cells
B. Interfascicular cambium join with intrafasciciular cambium
C. Parenchymatous cells present between vascular bundles become meristematic
D. Pith get obliterated

Answer

To answer the question "When secondary growth is initiated in dicot stem, what will happen first?", we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Secondary Growth**:
- Secondary growth refers to the increase in the girth or width of the plant stem. This process is crucial for the plant's ability to support itself as it grows taller.

2. **Role of Secondary Meristem**:
- Secondary growth requires the presence of secondary meristematic tissues, which are responsible for the formation of new vascular tissues.

3. **Identifying the Initial Event**:
- The first event in secondary growth is the activation of certain cells in the vascular bundles. These cells become meristematic, meaning they regain the ability to divide and differentiate into various types of cells.

4. **Formation of Cambium**:
- The cambium is a type of meristematic tissue that forms between the xylem and phloem. It is essential for secondary growth as it produces new xylem and phloem cells.

5. **Evaluating the Options**:
- **Option A**: "Cells of cambium divide periclinically to form xylem mother cells." - This happens after the cambium is formed, so it is incorrect.
- **Option B**: "Interfascicular cambium joins with intrafascicular cambium." - This occurs later in the process, so it is also incorrect.
- **Option C**: "Parenchymatous cells present between vascular bundles become meristematic." - This is the correct answer as it represents the first step in initiating secondary growth.
- **Option D**: "Pith gets obliterated." - This is a consequence of secondary growth, not the first event.

6. **Conclusion**:
- The correct answer is **Option C**: "Parenchymatous cells present between vascular bundles become meristematic."