"Aestivation (in botanical terms) is the arrangement of sepals and petals in floral buds with respect to other members of the whorl."
It is often confused with vernation, which is the arrangement of scales and new leaves in a leaf bud before it opens.
The sepals and petals are collectively known as a perianth.
Types of aestivation:
Valvate
Imbricate
Twisted
Vexillary
Quincuncial
1) Valvate
In this type of arrangement, the sepals and petals whorls just touch each other at the margin but do not overlap. E.g., Calotropis, Lilac, members of Annonaceae.
2) Imbricate
In this arrangement, the sepals and petals overlap each other but not in any regular manner or in a nonspecific direction. E.g., Gulmohar, Cassia.
3) Twisted
This type of aestivation shows a twisted look of the perianth, meaning that the petals and sepals overlap one another in one direction. E.g., Ladyfinger, Cotton, Chinarose.
4) Vexillary
It is also known as papilionaceous aestivation. It forms a whorl of five petals where the largest petal overlaps the two frontal petals, which in turn overlaps the two anterior smaller petals. E.g., Pea, bean.
5) Quincuncial
In this type, the whorls are spirally arranged. 3 petals are external, which shadow the two petals on the inside. E.g., Guava
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Aestivation:
Definition:
"Aestivation (in botanical terms) is the arrangement of sepals and petals in floral buds with respect to other members of the whorl."
Types of aestivation:
1) Valvate
In this type of arrangement, the sepals and petals whorls just touch each other at the margin but do not overlap. E.g., Calotropis, Lilac, members of Annonaceae.
2) Imbricate
In this arrangement, the sepals and petals overlap each other but not in any regular manner or in a nonspecific direction. E.g., Gulmohar, Cassia.
3) Twisted
This type of aestivation shows a twisted look of the perianth, meaning that the petals and sepals overlap one another in one direction. E.g., Ladyfinger, Cotton, Chinarose.
4) Vexillary
It is also known as papilionaceous aestivation. It forms a whorl of five petals where the largest petal overlaps the two frontal petals, which in turn overlaps the two anterior smaller petals. E.g., Pea, bean.
5) Quincuncial
In this type, the whorls are spirally arranged. 3 petals are external, which shadow the two petals on the inside. E.g., Guava
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