Roots of which of the following plants are involved in nitrogen fixation?

Options

A. Cycas
B. Pinus
C. Banyan
D. Peepal

Answer

To determine which plant's roots are involved in nitrogen fixation, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Nitrogen Fixation**:
- Nitrogen fixation is the process of converting atmospheric nitrogen (N₂) into a form that plants can use, such as ammonium (NH₄⁺) or nitrates (NO₃⁻). This process is crucial for plant growth as nitrogen is an essential nutrient.

2. **Identifying Nitrogen-Fixing Organisms**:
- Nitrogen fixation can be carried out by certain bacteria and cyanobacteria. The most well-known nitrogen-fixing bacteria are from the genus *Rhizobium*, which form symbiotic relationships with the roots of leguminous plants.

3. **Recognizing Leguminous Plants**:
- Leguminous plants, such as peas, beans, and lentils, have root nodules where *Rhizobium* bacteria reside. These nodules are often pink in color due to the presence of leghemoglobin, which helps in the oxygen supply to the bacteria.

4. **Examining Other Plants**:
- While legumes are the most common nitrogen-fixing plants, some non-leguminous plants also have specialized roots for nitrogen fixation. For example, the gymnosperm *Cycus* has coralloid roots that host nitrogen-fixing bacteria.

5. **Evaluating the Options**:
- The question provides multiple options, and we need to identify which of these plants have roots involved in nitrogen fixation.
- If the options include legumes, they would be correct. However, if they include *Cycus*, that would also be a valid answer due to its coralloid roots.

6. **Conclusion**:
- Based on the information, if the options include *Cycus*, that would be the correct answer for the plant whose roots are involved in nitrogen fixation. If legumes are present in the options, they would also be correct.

### Final Answer:
The roots of *Cycus* are involved in nitrogen fixation.