During secondary growth of dicot root, origin of complete phellogen and partial vascular cambium is from

Options

A. Conjunctive tissue
B. Endodermis
C. Pericycle
D. Cortex

Answer

To solve the question regarding the origin of complete phellogen and partial vascular cambium during the secondary growth of dicot roots, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Secondary Growth**:
- Secondary growth is a process that occurs in dicots (angiosperms) and is responsible for the increase in thickness of the plant. It is not observed in monocots.

2. **Identify the Structures Involved**:
- In dicot roots, secondary growth involves the formation of phellogen (cork cambium) and vascular cambium.
- Phellogen gives rise to the outer protective layer (cork), while vascular cambium contributes to the formation of secondary xylem and phloem.

3. **Determine the Origin of Phellogen and Vascular Cambium**:
- Phellogen originates from the pericycle, which is a layer of cells located just inside the endodermis.
- The vascular cambium, which is responsible for secondary growth, also has its origin from the pericycle.

4. **Conclusion**:
- Since both phellogen and vascular cambium originate from the pericycle during secondary growth, the correct answer to the question is **pericycle**.

### Final Answer:
The origin of complete phellogen and partial vascular cambium during secondary growth of dicot root is from the **pericycle**.

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