The circinate venation is the characteristic feature of ferns. It refers to

Options

A. Coiling of young leaves
B. Arrangement of leaves on stem
C. Attachment of sori on leaves
D. Hetrophylly

Explanation

**Step-by-Step Solution:**

1. **Understanding Venation**: Venation refers to the arrangement of veins in a leaf. It is an important characteristic that helps in identifying different types of plants.

2. **Identifying Circinate Venation**: Circinate venation is a specific type of venation found in ferns. It is characterized by the coiling of young leaves as they emerge from the shoot.

3. **Characteristics of Circinate Venation**: In circinate venation, the young leaves are rolled up in a spiral form. This coiling protects the delicate leaf tissues as they develop and unfurl.

4. **Conclusion**: Therefore, circinate venation refers to the coiling of young leaves, which is a distinctive feature of ferns.

**Final Answer**: Circinate venation refers to the coiling of young leaves.

---