Aestivation is the arrangement of sepals and petals in a flower. There are four types of arrangement that include valvate, twisted, imbricate and vexillary.Complete answer:
Aestivation is the arrangement of sepals and petals inside the buds before it opens. Here is the major type of aestivation:
1. Valvate aestivation: In such types of arrangements sepals and petals are arranged in a whorl and they only touch on the sides or margins. Such type of arrangements is found in Hibiscus
2. Twisted aestivation: In such a type of arrangement petals or sepals overlap with the next one. It may be in one direction only clockwise or anticlockwise.
3. Imbricate aestivation: In such a type of arrangement one petal or sepal is internal or overlapped on both the margins. Another one petal or sepal is external with both of its margins overlapping.
4. Vexillary aestivation: It is a unique type of arrangement where the smaller petals are covered by one large petal. The larger petal is called a vexillum, while the two curved petals which are called wings are in lateral position.Note:
Twisted aestivation is found in Malvaceae and has flowers like Hibiscus
, Malva, or in china rose. Aestivation also helps in detecting the sex of the plant. Arrangement of ovule and ovary if it's superior or inferior.