Aestivation is the mode of arrangement of sepals or petals with respect to the other members of the same whorl.
In a certain type of aestivation, sepals or petals are arranged without overlap and the margins of the petals touch one another.\
The described aestivation is called
Valvate
In plants such as , sepals or petals do not overlap, but touch each other at the margins. This type of aestivation is called valvate.