Vascular bundles in which xylem and phloem surround one another is called

Options

A. Conjoint
B. Radial
C. Collateral
D. Concentric

Answer

To solve the question regarding the type of vascular bundles in which xylem and phloem surround one another, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Vascular Bundles**: Vascular bundles are arrangements of xylem and phloem in plants. They play a crucial role in the transport of water, nutrients, and food.

2. **Identify the Types of Vascular Bundles**: There are different types of vascular bundles based on the arrangement of xylem and phloem:
- **Collateral**: In this type, phloem is located outside the xylem.
- **Radial**: In radial bundles, xylem and phloem are arranged on different radii, meaning they are side by side but not surrounding each other.
- **Concentric**: In concentric bundles, xylem and phloem surround one another.

3. **Analyze the Options**:
- **Constant**: Not relevant to the arrangement of xylem and phloem.
- **Radial**: This type does not have xylem and phloem surrounding each other.
- **Collateral**: Here, phloem is outside xylem, not surrounding it.
- **Concentric**: This is the type where xylem and phloem surround one another.

4. **Conclusion**: Based on the definitions and arrangements discussed, the correct answer to the question is that vascular bundles in which xylem and phloem surround one another are called **concentric** vascular bundles.

### Final Answer:
The vascular bundles in which xylem and phloem surround one another is called **concentric**.

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