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

References

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