The flower of many angiospermic plants which show sepals and petals differe with respect to the arrangement of sepals and petals in respective whorls''. Explain

Explanation

The mode of arrangement of sepals or petals in floral bud is known as Aestivation. It is of 4 types.
A) Valvate : ..When sepals or petals in a whorl just touch one another at the margins without overlapping...
Ex : Calotropis.

B) Twisted : ..If the margin of the appendage overlaps that of the next one and so on...
Ex : Cotton, Hibiscus. (Petals).
C) Imbricate : If the margins of sepals or petals overlap one another but not in any particular direction. Ex : Cassia, gulmohar.
D) Vexillary : 5 petals are present, of which the largest (standard) overlaps the two lateral petals (Wings) which in turn overlap the two smallest anterior petals (keel). This is known as vexillary or papilionaceous aestivation. Ex : Pea, Bean.