Histogens are components of

Options

A. apical meristem
B. intercalary meristem
C. lateral meristem
D. secondary meristem

Answer

**Step-by-Step Solution:**

1. **Understanding Histogens**: Histogens are components of the apical meristem, which is a type of meristematic tissue found at the tips of roots and shoots in plants.

2. **Types of Meristem**: There are several types of meristems, including apical meristem, intercalary meristem, lateral meristem, and secondary meristem. However, histogens are specifically associated with the apical meristem.

3. **Histogen Theory**: The concept of histogens is part of the Histogen Theory, which was proposed in 1817. This theory categorizes the apical meristem into three distinct zones, each responsible for forming different types of tissues.

4. **Identifying the Three Histogens**:
- **Dermatogen**: This histogen forms the outer layer of the plant, which develops into the epidermis.
- **Pleurome**: This histogen is responsible for forming the inner layer of vascular tissues, including the primary xylem and phloem.
- **Periblem**: This histogen gives rise to the middle layer of tissues, which includes the hypodermis, cortex, and endodermis.

5. **Conclusion**: Therefore, histogens are components of the apical meristem and play a crucial role in the development of the plant's primary tissues.

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