what is valvet, twisted, imbricate and vexillary aestivation ?
these are the aestivation of the flower i.e,how the petals are arranged on the floral axis with respect to each other.
twisted-in this type,one margin or end of petals is dominating/overlapping to the other and other is dominated by other/overlapped.
valvate-in this type the end of petals just slightly touch each other but are not overlapping or ovrlapped.
vexillary-the petals are five in no. in which one is superior and posterior.it is biggest of all petals and is called vexillum,other two are laterally arranged and overlapped by vexillum and called alae.the rest 2 are inferior and interior,they are overlapped by alae.