Aestivation (botany)

Aestivation (botany)
A diagram showing some kinds of tepal aestivation in flower buds. A: imbricate; B,C: cochleate; D: contorted; E: valvate; F: open.
Petals of Phlox develop with contorted aestivation

Aestivation or estivation, refers to 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.[1] Classes of aestivation include:

  • cochleate
  • contorted or twisted — every petal or sepal is outside its neighbour on one margin, and inside its neighbour on the other margin
  • contortiplicate
  • crumpled
  • decussate
  • imbricate — where one petal or sepal is outside all others, one is inside all others, and the others are outside on one margin and inside on the other
  • induplicate
  • open - petals or sepals do not overlap or even touch each other
  • quincuncial
  • reduplicate
  • valvate — petals or sepals touch without overlapping


  1. ^ Hickey, M.; King, C. (2001). The Cambridge Illustrated Glossary of Botanical Terms.. Cambridge: Cambridge University Press,.