Valvate aestivation is found in Calotropis, tulip, Asparagus, colchicum, Petunia, mustard and tobacco. Sweet pea, groundnut, soyabean, Indigofera, Sesbania have vexillary aestivation. Related Theory The mode of arrangement of either sepals or petals of a flower in bud condition is said to be an Aestivation. In valvate aestivation, Sepals or petals in a whorl just meet by their edges without overlapping. In Descending imbricate or vexillary aestivation the posterior petal of overlaps one margin of the two lateral petals. (Ref. to Fig. 14.4) 