Define circinate ptyxis .

Explanation

**Step-by-Step Text Solution:**

1. **Definition of Circinate Ptyxis**: Circinate ptyxis refers to a specific type of leaf arrangement found primarily in ferns, where the young leaves (also known as fronds) are coiled up in a spiral form at their tips.

2. **Characteristics**: The coiling resembles a spring or a fiddlehead, which is a term often used to describe these young, curled leaves. This unique arrangement is a protective adaptation.

3. **Function**: The primary function of circinate ptyxis is to protect the growing tip of the leaf. By being coiled, the tender, developing parts of the leaf are shielded from potential damage from environmental factors or herbivores.

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