Question

Aestivation in petals in flower of cotton is correctly shown in-

Answer 1

Hint:The positional arrangement of whorls of a flower within a flower bud even before it has blossomed is called aestivation. Aestivation is also known as prefoliation or praefoliation, these terms can also be defined as vernation, which is the arrangement of leaves within a vegetative bud.

Complete answer:
Aestivation is considered important from a view of taxonomic diagnosis. Let’s take an example of Malvaceae flower buds, members of malvaceae have their sepals arranged in valvate manner, but there is an exception in general Fremontodendron and Chiranthodendron, which sometimes have misplaced arrangement.
The aestivation in different flowers is classified as-
>Twisted Aestivation- in twisted aestivation, one margin of petal or sepal overlaps the margin of the next one. Example- China rose.
>Valvate Aestivation- in valvate aestivation, sepals or petals are arranged in a whorl in a way that they touch the margin of one another. Example- Calotropis.
>Imbricate Aestivation- Margin of petal or sepal overlaps in a particular manner as in Gulmohar.
>Vexillary Aestivation- five petals are arranged into a large standard petal or vexillum, overlapping two lateral petals known as wings which in turn overlap the smallest anterior petals called keel. This is the characteristic feature of the Papilionaceae family. Example- garden pea.
>Quincuncial Aestivation- in this, the petals are arranged in such a manner that two petals lie completely out of the whorl and two completely inside while one is half out and half in. Example- Ranunculus.
The cotton plant has twisted aestivation.

Hence the correct answer is option ‘D’.
Note:Mode of arrangement of petals and sepals in a bud with respect to other members of the same whorl is known as aestivation. In the options of the questions, A. is vexillary, B is imbricate, C is valvate and D is twisted.