Botany - Morphology of Flowering Plants Question with Solution | TestHub

The mode of arrangement of sepals or petals in the floral bud with respect to the other members of the same whorl is known as aestivation. The main types of aestivation are valvate, twisted, imbricate, and vexillary.

In pea and bean flowers, there are five petals, the largest (standard) overlaps the two lateral petals (wings) which in turn overlap the two smallest anterior petals (keel); this type of aestivation is known as vexillary or papilionaceous (Figure A). When sepals or petals in a whorl just touch one another at the margin, without overlapping, as inCalotropis, it is said to be valvate (Figure B). If the margins of sepals or petals overlap one another but not in any particular direction as inCassiaand Gulmohar, the aestivation is called imbricate (Figure C). If one margin of the appendage overlaps that of the next one and so on as in china rose, lady's finger and cotton, it is called twisted (Figure D).