Aestivation: The Floral Arrangement

Aestivation (in botanical terms) is 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.

It serves as a major identification point of flowers. There are five types of aestivation known. Let us look at them in detail.

Types of Aestivation

Valvate

In this type of arrangement, the sepals and petals whorls just touch each other at the margin but do not overlap. E.g., Calotropis, Lilac, members of Annonaceae.

Imbricate

In this arrangement, the sepals and petals overlap each other but not in any regular manner or in a nonspecific direction. E.g., Gulmohar, Cassia.

Twisted

This type of aestivation shows a twisted look of the perianth, meaning that the petals and sepals overlap one another in one direction. E.g., Ladyfinger, Cotton, Chinarose.

Vexillary

It is also known as papilionaceous aestivation. It forms a whorl of five petals where the largest petal overlaps the two frontal petals, which in turn overlaps the two anterior smaller petals. E.g., Pea, bean.

Quincuncial

In this type, the whorls are spirally arranged. 3 petals are external, which shadow the two petals on the inside. E.g., Guava

This sums up aestivation and its types.

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FAQs

What are two types of inflorescence?

The two types of the inflorescence are Racemose and Cymose inflorescence.

Which type of aestivation is found in China rose?

China rose has a twisted type of aestivation.

What is the aestivation of mustard?

Mustard flowers have an imbricate type of aestivation.

Which aestivation is found in tulips?

Tulips have a valvate type of aestivation.

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