Question

The mode of arrangements of sepals or petals in a floral bud is known as aestivation. Draw the various types of aestivation possible for a typical pentamerous flower.

Answer 1

Types of aestivation

The mode of arrangements of sepals or petals in a floral bud is known as aestivation. The main types of aestivation are valvate, twisted, imbricate and vexillary.

Valvate aestivation

The type of aestivation in which the sepals or petals in a whorl just meet one another at the margin without overlapping or turning, is said to be valvate. Example is Calotropis.



Twisted aestivation

The type of aestivation in which one margin of the sepals overlaps that of the next one and so on, is called twisted. Twisting may either be clockwise or anticlockwise. Examples are china rose, cotton and lady’s finger.



Imbricate aestivation
The type of aestivation in which the margins of sepals or petals overlap one another, however not in any particular direction, is called imbricate. Examples are Cassia and gulmohur.


Vexillary aestivation
The type of aestivation in which out of the five petals, the largest or standard overlaps the two lateral petals or wings which then overlap the two smallest anterior petals or keel, is called vexillary or papilionaceous. Examples are pea and bean flowers.