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Aestivation (botany)

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– Terms for aestivation are the same as leaf vernation
– Classes of aestivation: crumpled, decussate, imbricate, contorted, twisted
– Classes continued: cochleate, contortiplicate, quincuncial, induplicate, open
– Classes continued: reduplicate, valvate, vexillary
– Examples: Lilac – valvate aestivation, Phlox – contorted aestivation, Vinca minor – contorted aestivation, Ipomoea – contortiplicate aestivation, Merremia tuberosa – contortiplicate aestivation

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

A diagram showing some kinds of petal or sepal aestivation in flower buds. A: quincuncial; B: twisted, C: cochleate; D: contorted; E: valvate; F: open.

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.

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