Aestivation, in botanical terms, refers to the arrangement of sepals and petals in floral buds with respect to other members of the whorl. It is often confused with vernation, which is the arrangement of scales and new leaves in a leaf bud before it opens. The sepals and petals are collectively known as a perianth, and the arrangement of the perianth serves as a major identification point of flowers. There are five types of aestivation known, which are as follows:

• Valvate: In this type of arrangement, the sepals and petals whorls just touch each other at the margin but do not overlap. Examples include Calotropis, Lilac, and members of Annonaceae.

• Imbricate: In this type of arrangement, the sepals or petals overlap one another in a manner similar to roof tiles. Examples include Cassia, Gulmohar, and members of the family Fabaceae.

• Twisted: In this type of arrangement, the sepals or petals are twisted around each other. Examples include China rose, Cotton, and members of the family Malvaceae.

• Induplicate: In this type of arrangement, the margins of the sepals or petals are folded inwards. Examples include Tecoma, Bignonia, and members of the family Bignoniaceae.

• Reduplicate: In this type of arrangement, the margins of the sepals or petals are folded outwards. Examples include Datura, Brinjal, and members of the family Solanaceae.

Aestivation is an important characteristic of flowers and can be used to identify different species.