Question

Aestivation of petals in family Malvaceae is-
A. Valvate
B. Imbricate
C. Twisted
D. Vexillary

Answer 1

Hint: Aestivation is a mode of arrangement of petals or sepals in a floral bud with respect to the other members present in the same whorl. There are mainly five types of aestivation- valvate, twisted, imbricate, vexillary, and quincuncial. It is basically the positional arrangement of floral whorls before the opening of the flower i.e., in the bud stage.

Complete answer: The various types of aestivation are-
1. Valvate aestivation- Sepals or petals just touch the margin of one another when arranged in a whorl. It is seen in Calotropis.
2. Twisted aestivation- Among the appendages on the margin overlaps the next one in a particular order. Seen in China rose.
3. Imbricate aestivation- Margin of flower overlaps one another but in any arranged fashion, as seen in Gulmohar.
4. Vexillary aestivation: There are five petals in plants having such arrangement which are differentiated into two large petals or sepals called standard or vexillum. These two large petals overlap two small lateral petals called wings, which in turn overlap the smallest anterior petals called keel or carina. This is the characteristic of the Papilionaceae family and that’s why it is also called papilionaceous aestivation.
5. Quincuncial aestivation- In this type two petals are completely out of the whorl and two of them are completely inside, while the fifth petal is half inside and half outside, seen in Ranunculus.
In the Malvaceae family, both valvate and twisted types of aestivations are present, valvate aestivation is possessed by sepals which are five in number, and the petals which are five, polypetalous show twisted aestivation. Generally, we define this aestivation term for corolla to be more particular petals.
Hence, the correct answer is option (C).

Note: Malvaceae family is called the Mallows, or the cotton family. It includes some famous plants like okra (bhindi), cotton, Malva (mallow), Hibiscus, etc. Sepals are the unit of the calyx. In the Malvaceae family, the sepals are united i.e., gamosepalous, having valvate aestivation. Petals are the unit of the corolla. In this family, the aestivation of petals is twisted and they are polypetalous and inferior.