Actinomorphic (star-shaped) can be divided into 3 or more identical sectors, which are related to each other by rotation about the centre of the flower, e.g., China rose. Zygomorphic flowers can be divided by only a single plane into two mirror image halves, e.g., orchids.
Valvate aestivation The sepals or petals in a whorl just touch one another at the margin, e.g., Calotropis.
Twisted aestivation One margin of the appendage overlaps that of the next one, e.g., China rose. Imbricate aestivation the margins of sepals or petals overlap but not necessarily in specific direction, e.g., Cassia. For further detail refer to ans. 97