What do you mean by aestivation.

Explanation

**Step-by-Step Solution:**

1. **Definition of Aestivation:**
Aestivation refers to the arrangement of the sepals and petals in a flower bud before it opens. It describes how these floral parts are positioned relative to each other.

2. **Types of Aestivation:**
There are several types of aestivation, each characterized by the way the petals and sepals overlap or touch:
- **Valvate Aestivation:** In this type, the margins of the petals or sepals do not overlap; they merely touch each other. An example of this is seen in the flower of Calotropis.
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