In Cycas specialised roots are associated with `N_(2)` fixing cyanobacteria, called-

Options

A. Tap root
B. Coralloid root
C. Adventitious root
D. All the above

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about the specialized roots in Cycas that are associated with nitrogen-fixing cyanobacteria.

2. **Identifying the Roots in Cycas**: In Cycas, there are different types of roots, including tap roots, coralloid roots, and adventitious roots.

3. **Focus on Nitrogen-Fixing Cyanobacteria**: The key point in the question is the association with nitrogen-fixing cyanobacteria. In Cycas, the roots that are specifically associated with nitrogen-fixing cyanobacteria are known as coralloid roots.

4. **Characteristics of Coralloid Roots**: Coralloid roots are irregular in shape, negatively geotropic (they grow upwards), and they do not possess root hairs or root caps. They have a specific zone known as the algal zone, which is where the cyanobacteria reside.

5. **Conclusion**: Based on the information, the specialized roots in Cycas that are associated with nitrogen-fixing cyanobacteria are called **coralloid roots**.

### Final Answer:
The specialized roots in Cycas associated with nitrogen-fixing cyanobacteria are called **coralloid roots**.

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