Which of the following is a flowering plant with nodules containing filamentous nitrogen-fixing microorganism

Options

A. Cicer arietinum
B. Casuarina equisetifolia
C. Crotalaria juncea
D. Cycas revolute

Answer

To determine which of the following is a flowering plant with nodules containing filamentous nitrogen-fixing microorganisms, we will analyze each option provided.

### Step-by-Step Solution:

1. **Understanding Nitrogen-Fixing Microorganisms**:
- Nitrogen-fixing microorganisms are prokaryotic organisms that convert atmospheric nitrogen into fixed nitrogen compounds, which are essential for plant growth. These microorganisms often form symbiotic relationships with certain plants, leading to the formation of root nodules.

2. **Analyzing the Options**:
- **Option 1: Cicer arietinum (Chickpea)**:
- Chickpea is a pulse crop and does have root nodules containing Mesorhizobia, which fix nitrogen. However, it is not classified as a flowering plant in the context of this question. Thus, this option is incorrect.

- **Option 2: Casuarina equisetifolia**:
- This plant is an angiosperm (flowering plant) and has root nodules formed due to filamentous species of actinomycetes. This means it contains nitrogen-fixing microorganisms in its nodules. Therefore, this option is correct.

- **Option 3: Crotalaria juncea**:
- Crotalaria is a legume and is used as green manure. However, it does not contain filamentous symbiotic nitrogen fixers in its nodules. Hence, this option is incorrect.

- **Option 4: Cycas revoluta**:
- Cycas revoluta is a gymnosperm and contains cyanobacteria in its colloid roots, which assist in nitrogen fixation. However, it does not have root nodules and is not a flowering plant. Thus, this option is also incorrect.

3. **Conclusion**:
- After analyzing all the options, the only flowering plant with nodules containing filamentous nitrogen-fixing microorganisms is **Casuarina equisetifolia**.

### Final Answer:
The flowering plant with nodules containing filamentous nitrogen-fixing microorganisms is **Casuarina equisetifolia**.