Aestivation-Mode of arrangement of sepals or petals in a floral bud with respect to other member of same whorl is called aestivation. It is of following types- (a) Valvate-The margins of sepals or petals, present in whorl just touching each other. eg → Calotropis. (b) Twisted- Margin of one petal or sepal overlaps the margin of adjacent one. Egchina rose, ladyfinger, cotton. (c) Imbricate-Margins of petals or sepals overlaps each other but not in a particular direction. Eg-Cassia, Gulmohar. (d) Vexillary-Largest petal(standard) overlaps two smaller lateral petals (wings) which in turn overlaps two smallest anterior petals (Keel) eg → Pea, bean flower.