. what is Aestivation? What are types of aestivation


Best Answer

The mode of arrangement of petals or sepals in bud condition, with respect to each other in same whorl is called aestivation.  It is of following types.

i)Valvate

Here margin of petals of a whorl touches each other.  e.g. Calyx of Hibiscus.

ii)Twisted or contorted

Here margin of a petal of a whorl overlaps the margin of the adjacent petal and the other margin is overlapped by the margin of adjancent petal.  e.g. Corolla of Datura and Hibiscus.

iii)Ascending imbricate

When both margins of one of the petals are overlapped by the others and both margins of another one are external.  For rest of the petal one end is overlapped and other end is overlapping Eg. Corolla of Caesalpinaceae, Eg. Cassia.

iv)Descending imbricate or vexillary

Here posterior petals overlaps lateral ones and lateral overlaps the anterior petals.  e.g. Corolla of Fabaceae, Eg. Pisum sativum. 

v)Quincuncial

It is a special type of imbricate aestivation.

•Two petals are completely external.

•Two petals are completely internal.

•And in one petal one end is overlapped and other end is overlapping.  

e.g. Cucurbita maxima, Ranunculus,calyx of Ipomoea and Catharanthus. 

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