The arrangement of accessory whorls (calyx, corolla) in relation to one another in the floral bud is called as aestivation.
The different types of aestivation are:Type Description Arrangement
1. ValvatePetals or sepals meet each other at the edges.Arranged without overlappingCalyx of Hibiscus
2. TwistedPetals or sepals show overlapping.Overlapping is done by one margin of each petal over the margin of adjacent petalsCorolla of Hibiscus
3. ImbricateMargins of petals overlap each other in such a way that one petal is completely external, one petal is completely internalCassia, Bauhina
4. VexillaryIt is seen in papilionaceous form of corolla.Posterior petal is external and largest, it almost covers the two lateral petals and lateral petals in turn overlap two smallest anterior petalsPisum sativum (Garden Pea)
5. QuincuncialMargins of petals overlap each other in such a way that two petals are completely external, two petals are completely internalPsidium guajava