Vascular rays are formed by the activity of -

Options

A. Fusiform initials
B. Ray initials
C. Phellogen
D. Wound cambium

Answer

To answer the question "Vascular rays are formed by the activity of -", we need to analyze the options given and understand the formation of vascular rays in plants.

### Step-by-Step Solution:

1. **Understanding Vascular Rays**:
- Vascular rays, also known as medullary rays, are structures in the plant that facilitate the radial conduction of substances across the vascular bundles. They are primarily composed of parenchyma cells.

2. **Identifying the Origin**:
- Vascular rays originate from the vascular cambium, which is a layer of meristematic tissue in plants responsible for secondary growth.

3. **Types of Cells in Vascular Cambium**:
- The vascular cambium consists of two types of cells:
- **Fusiform Initials**: These are elongated cells that contribute to the formation of the vertical elements of the vascular system (xylem and phloem).
- **Ray Initials**: These are shorter, compartmentalized cells that give rise to the vascular rays.

4. **Formation of Vascular Rays**:
- The ray initials undergo a specific type of division known as periclinal division (or tangential division), which increases the number of ray cells and contributes to the formation of vascular rays.

5. **Conclusion**:
- Based on the above points, vascular rays are specifically formed by the activity of **ray initials** in the vascular cambium.

### Final Answer:
Vascular rays are formed by the activity of **ray initials**.

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