Positional arrangement of the parts of a flower within a flower bud before it has opened
This article is about the positional arrangement of the parts of a flower within a flower bud before it has opened. For other uses, seeAestivation (disambiguation).
A diagram showing some kinds of petal or sepal aestivation in flower buds. A: quincuncial; B: ascending cochleate; C: descending cochleate; D: contorted; E: valvate; F: open.
Aestivation orestivation is the positional arrangement of the parts of a flower within a flower bud before it has opened. Aestivation is also sometimes referred to aspraefoliation orprefoliation, but these terms may also meanvernation: the arrangement of leaves within a vegetative bud.
Aestivation can be an important taxonomic diagnostic; for exampleMalvaceae flower buds have valvate sepals, with the exception of the generaFremontodendron andChiranthodendron, which have sometimes been misplaced as a result.
contorted ortwisted – every petal or sepal is outside its neighbour on one margin, and inside its neighbour on the other margin.
cochleate – spirally twisted; may also refer to arrangements where one petal has its two edges outside those of the adjacent petals, one has its two edges both inside, and the other petals have one edge outside and the other inside.
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 calledstandard encloses two smaller petals.
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