Aestivation (botany)


Aestivation or estivation is the positional arrangement of the parts of a flower within a flower bud before it has opened. Aestivation is also sometimes referred to as praefoliation or prefoliation, but these terms may also mean vernation: the arrangement of leaves within a vegetative bud.
Aestivation can be an important taxonomic diagnostic; for example Malvaceae flower buds have valvate sepals, with the exception of the genera Fremontodendron and Chiranthodendron, which have sometimes been misplaced as a result.
The terms used to describe aestivation are the same as those used to describe leaf vernation.
Classes of aestivation include:
Vexillary aestivation is a special type of aestivation occurring in plants like pea. In this type of aestivation a large petal called standard encloses two smaller petals called