Vascular bundles of roots are

Options

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

Answer

To determine the nature of vascular bundles in roots, we can follow these steps:

### Step 1: Understand the Types of Vascular Bundles
Vascular bundles can be classified into several types based on their arrangement of xylem and phloem:
- **Conjoined**: Xylem and phloem are located together in a bundle.
- **Concentric**: Xylem and phloem are arranged in a concentric manner, one surrounding the other.
- **Bicollateral**: Xylem and phloem are present on both sides of the xylem.
- **Radial**: Xylem and phloem are arranged in separate groups on alternate radii.

### Step 2: Identify the Vascular Bundle in Roots
In roots, the vascular bundles are arranged in a radial pattern. This means that the xylem and phloem are positioned alternately in separate groups.

### Step 3: Confirm the Arrangement in Different Plant Types
Both monocots (monocotyledons) and dicots (dicotyledons) exhibit this radial arrangement in their roots. This is a distinguishing feature that helps in identifying the vascular structure in roots.

### Step 4: Eliminate Incorrect Options
- **Conjoined**: Incorrect for roots as they do not have xylem and phloem together in a single bundle.
- **Concentric**: Incorrect as this arrangement is found in stems of monocots and pteridophytes, not in roots.
- **Bicollateral**: Incorrect as this type is typically found in certain stems, not in roots.

### Conclusion
The correct answer is that the vascular bundles in roots are **radial**.