The leaves of ferns are microphyllous.

Answer

### Step-by-Step Solution:

1. **Understanding the Terminology**:
- The term "microphyllous" refers to leaves that are small and typically have a single vein.
- In contrast, "megaphyllous" refers to larger leaves that have a complex structure with multiple veins.

2. **Identifying the Leaf Structure in Ferns**:
- Ferns have leaves that are known as fronds. These fronds are characterized by their size and branching structure.

3. **Analyzing the Characteristics of Fern Leaves**:
- The leaves of ferns are not small; they are large and often have a complex network of veins. This structure is indicative of megaphyllous leaves.

4. **Conclusion**:
- The statement that "the leaves of ferns are microphyllous" is incorrect. The correct classification is that the leaves of ferns are megaphyllous.

5. **Final Statement**:
- Therefore, the correct answer is that the leaves of ferns are megaphyllous, also known as fronds.