Define aestivation.

Hint:Aestivation is often related to as prefoliation, but vernation can also mean these terms: the structure inside a vegetative bud of leaves.

Complete answer:
First we should know about aestivation to answer this question. Aestivation, in contrast to the other elements of the same whorl, is the method of arrangement of petals or sepals in a floral bud. In zoology, although hibernation relates to dormancy and during winter months, aestivation refers to a situation in which some animals during the humid, arid season go into dormancy or lack of movement.
There are four key forms of aestivation. They are the following:
1. Aestivation Valvate: Sepals or petals only meet one another in a whorl. They are not overlapping each other.
2. Aestivation Twisted: The edge of the next appendage overlaps one appendage edge. In Calotropis, it is found
3. Imbricate aestivation: Margins of sepals or petals intersect with each other, but not in any clear way.
4. Vexillary aestivation: It is often referred to as the papilionaceous aestivation form. In Cassia and Gulmohar, it is shown.
The five petals are there. The two lateral petals (named wings), that further cover the two smallest anterior petals (named keels), converge the largest petal (named standard).

Note:Aestivation may be an effective taxonomic diagnosis; excluding the genera Chiranthodendron, for instance, Malvaceae flower buds have valve sepals, which have often been misplaced as a consequence.