Q.Write notes on Vexillary aestivation.

Aestivation describes how the members of a floral whorl overlap (or don't) in the bud; the main types are valvate, twisted, and imbricate.

Before a flower opens, its sepals (calyx) or petals (corolla) are folded together in the bud in a characteristic pattern called AESTIVATION. Three common types are:

1. VALVATE - the margins of adjacent members just touch one another without any overlapping, like the valves/edges of a box lid (e.g. Calotropis).

2. TWISTED (contorted) - each member overlaps the one next to it in the same direction all the way around, so one margin of each member is covered by the neighbouring member while its other margin covers the next one (e.g. China rose/Hibiscus, Lady's finger).

3. IMBRICATE - the members overlap each other irregularly, but at least one member is completely external (its both margins outside) and at least one is completely internal (its both margins inside), with the rest partly overlapping (e.g. Cassia, Gulmohar, Gulmohar-type Caesalpiniaceae flowers).

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