The tip of the root apical meristem is capped by the histogen known as

Options

A. Periblem
B. Dermatogen
C. Plerome
D. Calyptrogen

Explanation

To answer the question, "The tip of the root apical meristem is capped by the histogen known as," we need to follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of Apical Meristem**: The apical meristem is a region of actively dividing cells at the tips of roots and shoots. This area is crucial for the growth of the plant.

2. **Identify the Role of Histogens**: Histogens are layers of cells in the meristematic tissue that give rise to different tissues in the plant. They are responsible for the formation of various parts of the plant structure.

3. **Know the Types of Histogens**: In the context of root apical meristem, there are specific histogens that contribute to the formation of different root structures. The main histogens include:
- **Dermatogen**: This gives rise to the epidermis.
- **Periblem**: This forms the cortex.
- **Plasmoderm**: This is involved in the formation of vascular tissues.

4. **Focus on the Root Cap**: The root cap is a protective structure that covers the tip of the root. It is essential for protecting the delicate meristematic cells as the root pushes through the soil.

5. **Identify the Histogen for the Root Cap**: The specific histogen responsible for the formation of the root cap is known as **Caliphron** (or Calyptrogen). This histogen is crucial for the development of the root cap.

6. **Conclusion**: Therefore, the answer to the question is that the tip of the root apical meristem is capped by the histogen known as **Caliphron**.

### Final Answer:
The tip of the root apical meristem is capped by the histogen known as **Caliphron**.

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