Cambium ring in dicot system is

Options

A. Primary meristerm in origin
B. Secondary meristem in origin
C. Promeristem in origin
D. Both primary and secondary meristem in origin

Answer

### Step-by-Step Solution:

1. **Understanding Cambium in Dicot Stems**:
- The cambium is a layer of tissue in plants that is responsible for secondary growth. In dicot stems, it plays a crucial role in increasing the diameter of the stem.

2. **Types of Cambium**:
- There are two types of cambium: primary and secondary.
- Primary cambium is associated with the initial growth of the plant, while secondary cambium is involved in the growth that occurs after the plant has matured.

3. **Interfascicular Cambium**:
- In dicot stems, the cambium ring consists of interfascicular cambium, which forms between vascular bundles.
- This cambium develops during the first year of growth, even before secondary growth begins.

4. **Function of Cambium**:
- The cambium is responsible for producing new xylem and phloem cells.
- It increases the diameter of the stem by producing more xylem than phloem, leading to the formation of annual rings.

5. **Formation of Annual Rings**:
- Annual rings are formed due to the seasonal growth patterns of the cambium.
- Early wood (with wide lumen vessels) is formed first, followed by late wood (with narrow lumen vessels), which together constitute the annual rings.

6. **Conclusion**:
- The cambium ring in dicot stems is derived from both primary and secondary meristematic tissues.
- Therefore, the correct answer to the question is that the cambium ring in dicot stems is "both primary and secondary meristem in origin."

### Final Answer:
The cambium ring in dicot stem is both primary and secondary meristem in origin.

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