What is meant by polypetalous?

What is called Aestivation? Describe its types.

In $Hibiscus$ $rosa-sinensis$,there is an additional floral whorl known as:

What is the characteristic posterior petal of the Papilionoideae corolla called?

In many cultivated ornamental flowers,the number of petal whorls is higher than that in the wild type. These extra petals are generally modified:

Vexillary aestivation is a characteristic feature of ...... flowers.