DENDROLOGY

Detailed explanation-1: -Explanation for the correct option : Aestivation is arrangement of accessory floral organs in relation to another floral bud. When the margins of sepals and petals overlap without any specific direction its is imbricate aestivation.

Detailed explanation-2: -Vexillary aestivation is a special type of aestivation. In valvate aestivation margins of adjacent petals or sepals touch each other at the margin without overlapping.

Detailed explanation-3: -Sepals and petals that are indistinguishable, as in lilies and tulips, are sometimes referred to as tepals.

Detailed explanation-4: -Imbricate: In this type of aestivation, the sepals and petals overlap each other in the nonspecific direction. Example: Cassia and Gulmohar. Twisted: In this type of aestivation, the sepals and petals overlap each other in one specific direction. Example: china rose and cotton.