Aestivation (botany)
{{short description|Positional arrangement of the parts of a flower within a flower bud before it has opened}}
{{About|the positional arrangement of the parts of a flower within a flower bud before it has opened||Aestivation (disambiguation)}}
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.
Terminology
The terms used to describe aestivation are the same as those used to describe leaf vernation.{{cite book|author =Hickey, M.|author2 =King, C. |year=2001 |title= The Cambridge Illustrated Glossary of Botanical Terms|publisher=Cambridge University Press|location=Cambridge}}
Classes of aestivation include:
- crumpled
- decussate
- imbricate – overlapping
- contorted or twisted – every petal or sepal is outside its neighbour on one margin, and inside its neighbour on the other margin.
- cochleate – spirally twisted.
- contortiplicate – contorted and also plicate.
- quincuncial – with five parts, where two petals or sepals are outside all others, two are inside all others, and the fifth is outside on one margin and inside on the other.
- induplicate – folded inwards.
- open – petals or sepals do not overlap or even touch each other .
- reduplicate – folded outwards.
- valvate – margins of adjacent petals or sepals touch each other without overlapping.
- vexillary – a special type of aestivation occurring in plants like pea; in this type of aestivation a large petal called standard encloses two smaller petals.
{{gallery
|File:Kashira lilacs 01.JPG|Lilac (Syringa vulgaris), valvate aestivation
|File:Phlox aestivation.jpg|Phlox (Phlox paniculata), contorted aestivation
|File:Vinca minor aestivation.jpg|Vinca minor, contorted aestivation
|File:Morning Glory Photo.jpg|Ipomoea, contortiplicate aestivation
|File:Starr 070302-5063 Merremia tuberosa.jpg|The corolla of Merremia tuberosa was contortiplicate in the bud.
}}