Roots are described as adventitious depending upon their :

Options

A. anatomy
B. function
C. place of origin
D. external structure

Explanation

**Step-by-Step Solution:**

1. **Understanding Roots**: Roots are the non-green, cylindrical structures of a plant that primarily function to absorb water and nutrients from the soil. They do not have nodes, leaves, or buds.

2. **Types of Root Systems**: There are three main types of root systems in flowering plants:
- **Tap Root System**: This system has a primary root that develops from the radical (the embryonic root) and persists throughout the plant's life.
- **Fibrous Root System**: In this system, the primary root is short-lived and is replaced by many smaller roots that arise from the base of the stem.
- **Adventitious Root System**: This system is characterized by roots that develop from any part of the plant other than the radical.

3. **Defining Adventitious Roots**: Adventitious roots are unique because they do not originate from the radical. Instead, they can emerge from stems, leaves, or other parts of the plant.

4. **Classification Basis**: The classification of roots as adventitious is based on their place of origin. This is the key distinguishing factor:
- **Tap Roots** originate from the radical.
- **Fibrous Roots** arise from the base of the stem.
- **Adventitious Roots** develop from any other part of the plant.

5. **Conclusion**: The correct answer to the question "Roots are described as adventitious depending upon their:" is **C) Place of origin**. This classification is not based on anatomy, function, or external structure but specifically on where the roots originate from in the plant.

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