Histogen tissues are classified on the basis of

Options

A. (a) Plane of division
B. (b) Type of cells they form
C. (c) Position
D. (d) Origin

Answer

### Step-by-Step Solution:

1. **Understanding Histogen Tissues**: Histogen tissues are specialized tissues found in the meristematic regions of plants, particularly at the growing tips of roots and shoots.

2. **Classification of Histogen Tissues**: Histogen tissues are classified based on the types of cells they produce. This classification is essential for understanding the roles these tissues play in plant development.

3. **Three Distinct Zones**: Histogen tissues are divided into three distinct zones:
- **Dermatogen**: This is the outermost layer, which gives rise to the epidermis of the plant.
- **Periblem**: This is the middle layer that develops into the cortex and endodermis.
- **Pleurome**: This is the innermost layer that forms the vascular tissues, including the pith and stele.

4. **Historical Context**: The classification of histogen tissues was first described by the scientist Hanstein, who identified these zones based on the types of cells they form.

5. **Evaluating Answer Options**:
- Option A (Plane of division) is incorrect.
- Option B (Type of cells they form) is correct.
- Option C (Position) is incorrect.
- Option D (Origin) is incorrect.

6. **Conclusion**: The correct answer to the question is **B**, as histogen tissues are classified based on the types of cells they produce.