name the meristems which appear later in life of dicotyledonous and gymnosperms plants and causes increase in the girth of the organ in which they are active.

Answer

To answer the question regarding the meristems that appear later in the life of dicotyledonous and gymnosperm plants and cause an increase in the girth of the organs, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Meristems**:
- Meristems are regions in plants where cells continuously divide, leading to growth. They are classified into primary and secondary meristems.

2. **Identifying the Type of Growth**:
- The question specifies an increase in girth, which indicates secondary growth. This type of growth is responsible for thickening the plant's stems and roots.

3. **Recognizing the Meristems Involved in Secondary Growth**:
- In dicotyledons and gymnosperms, the lateral meristems are responsible for secondary growth. These include:
- **Vascular Cambium**: This meristem produces secondary xylem (wood) and secondary phloem (bark), contributing to the increase in girth.
- **Cork Cambium**: This meristem produces cork cells, which form the outer protective layer of the plant.

4. **Conclusion**:
- Therefore, the meristems that appear later in the life of dicotyledonous and gymnosperm plants and cause an increase in the girth of the organs are the **vascular cambium** and **cork cambium**.

### Final Answer:
The meristems responsible for the increase in girth in dicotyledonous and gymnosperm plants are the **vascular cambium** and **cork cambium**.

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