Vascular bundle having phloem at the centre encircled by xylem is know as

Options

A. bicollateral
B. conjoint collateral
C. amphivasal
D. amphicribal

Answer

To solve the question "Vascular bundle having phloem at the centre encircled by xylem is known as," we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure of Vascular Bundles**: Vascular bundles are composed of two main types of tissues: xylem and phloem. Xylem is responsible for water transport, while phloem transports nutrients.

2. **Identify Types of Vascular Bundles**: There are several types of vascular bundles based on the arrangement of xylem and phloem:
- **Collateral**: Phloem is located outside the xylem.
- **Bicollateral**: Phloem is located both outside and inside the xylem.
- **Concentric**: One type of tissue surrounds the other.
- **Radial**: Xylem and phloem are arranged alternately.

3. **Focus on the Concentric Type**: The concentric type can be further divided into:
- **Amphivasal**: Xylem surrounds the phloem.
- **Amphicribble**: Phloem surrounds the xylem.

4. **Analyze the Question**: The question specifies that the phloem is at the center and is encircled by xylem. This matches the definition of the **amphivasal** type of vascular bundle.

5. **Eliminate Incorrect Options**:
- **Bicollateral**: Phloem is not at the center; it is at the periphery.
- **Collateral**: Phloem is also outside the xylem.
- **Amphicribble**: Phloem surrounds xylem, which contradicts the question.

6. **Conclusion**: The correct answer is **amphivasal**, as it is the only type where phloem is at the center and encircled by xylem.

### Final Answer:
The vascular bundle having phloem at the centre encircled by xylem is known as **amphivasal**.