Question

Identify the correct aestivations.

A. a- Valvate, b- Twisted, c-Vexillary, d-Imbricate.
B. a- Valvate, b- Twisted, c- Imbricate, d- Vexillary.
C. a- Valvate, b- Vexillary, c- Twisted, d- Imbricate.
D. a-Vexillary, b- Imbricate, c- Twisted, d-Valvate.
E. a- Valvate, b- Imbricate, c- Twisted, d- Vexillary.

Answer 1

Hint: Aestivation is the arrangement of petals in the bud. Aestivation can be understood by observing the overlap pattern of the ends of petals.

Complete answer:
Aestivation is the arrangement of the parts of the flowers in a position in the flower bud before it's opening with respect to the other members in the same whorl. There are four different types of aestivation which are-
1. Valvate aestivation- In this of aestivation, sepals or petals are close to each other or you can say they touch each other but they do not overlap with each other. Example is mustard.
2. Twisted aestivation- It is a type of aestivation as the name indicates it is kind of a twisted one where one margin of the appendages overlaps the margins of next appendages. It is observed in china rose.
3. Imbricate aestivation- In this type of aestivation, the margins of sepals or the petals overlap one another but there is not a particular direction of their overlapping. Example is cassia.
4. Vexillary aestivation- This type of aestivation is seen in pea. In this there is a presence of five petals, the largest one overlaps the two lateral one and that lateral ones further overlaps the two smallest ones.

So, if we look at the diagrams, then in the first diagram sepals and petals are close to each other but they do not overlap and this type of aestivation is Valvate aestivation. So, the correct option would be where a- Valvate. This is seen in the first three options. So clearly the last options get eliminated.

In diagram B, there is overlapping of appendages but the one margin overlaps the margin of the next appendage as shown in diagram B and this type of aestivation is called twisted aestivation. So, the correct would be that one which has b- twisted. This is seen in option A and B and hence option C gets eliminated.

In the diagram C, the margins of sepals or petals overlap one another and the direction is not fixed so this one is imbricate aestivation. The correct option would be where c-Imbricate. This is seen in option B only.

In diagram D, there is a presence of five petals and the largest one overlaps the lateral two which further overlaps the smallest ones and therefore this one is Vexillary aestivation.

Hence, the correct answer is option (B).

Note: As per the explanation you should keep in mind all the types of aestivation and that would make it easier by answering the question only by looking at the diagram carefully. These aestivations are the positional arrangements of the parts of flowers.