The valamen of orchid root is derived from the
(a) Phellogen of root
(b) Plerome of root
(c) Dermatogen of root
(d) Periblem of root

Options

A. Phellogen of root
B. Plerome of root
C. Dermatogen of root
D. Periblem of root

Answer

To solve the question regarding the origin of the velumen in orchid roots, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Understanding Velumen**:
- Velumen is a type of spongy, multiple epidermis found in the roots of certain plants, particularly epiphytic or semi-epiphytic plants like orchids. It serves as a protective covering for the roots.

2. **Analyzing the Options**:
- **(a) Phellogen of root**: Phellogen, also known as cork cambium, is responsible for producing cork cells and is not involved in the formation of velumen.
- **(b) Plerome of root**: Plerome refers to the central part of the root that gives rise to the vascular tissue. It does not contribute to the formation of velumen.
- **(c) Dermatogen of root**: Dermatogen is the outermost layer of the root apical meristem that gives rise to the epidermis. Since velumen is a type of epidermis, this option is likely correct.
- **(d) Periblem of root**: Periblem is the layer of the root that gives rise to the cortex. It does not contribute to the formation of velumen.

3. **Conclusion**:
- Based on the analysis, the velumen of orchid roots is derived from the dermatogen of the root. Therefore, the correct answer is **(c) Dermatogen of root**.

### Final Answer:
The valamen of orchid root is derived from the **(c) Dermatogen of root**.