Aestivation

It is the arrangement of sepals or petals in the floral bud to the other members of the same whorl. Valvate aestivation – when margins of the petals are in contact with each other without any overlapping.

Flower

An angiosperm's distinctive reproductive structure is the flower. A typical flower has four main parts—or whorls—known as the calyx, corolla, androecium, and gynoecium.