Aestivation in Flowers and types.

 Aestivation, also known as vernation, refers to the arrangement of floral parts in a flower bud before it opens. It is a phenomenon that occurs in many plants, including some of the most popular flowering plants such as roses, lilies, and orchids. Aestivation is important because it determines the shape, size, and symmetry of the flower when it opens.

There are several types of aestivation patterns in flowers, including valvate, twisted, imbricate, and contorted. 

1. Valvate: When sepals or petals in a whorl just touch one another at the margin without overlapping, e.g. mustard (Brassica campestris), amaltas (Cassia fistula), etc. 

2. Twisted: When one margin of a sepal or petal overlaps that of the next one and the other margin is overlapped by the preceding one, giving a twisted appearance to the body. Overlapping is in one direction only, e.g. China rose (Hibiscus rosainensis). 

3. Imbricate: Out of the five sepals or petals one is completely external, one completely internal and in each of the remaining three, one margin is internal and other is external. It is of two types: 

(a) Ascending imbricate: The post rior sepal or petal is innermost, i.e. its both margins are overlapped, e.g. Caesalpinaceae such as Cassia, Bauhina, etc. 

(b) Descending imbricate or vexillary aestivation: The anterior petal is innermost and posterior petal is the largest and outermost, e.g. pea, beans, etc.

 4. Quinquincial: It is modification of imbricate type. Out of five petals or sepals two are completely internal, two completely external and in the remaining petal one margin is internal and the other margin is external, e.g. Murraya. 

Aestivation patterns are important because they can affect the appearance, function, and reproductive success of flowers. For example, flowers with valvate aestivation are typically more rounded and symmetrical, while those with twisted or contorted aestivation are often more irregular and asymmetrical. Additionally, the arrangement of floral parts can affect the way that insects and other pollinators interact with the flower, which can impact the flower's ability to reproduce.

In conclusion, aestivation in flowers refers to the arrangement of floral parts in a flower bud before it opens. There are several different types of aestivation patterns, each with its own unique characteristics and effects on the appearance and function of the flower. Understanding aestivation can help us appreciate the incredible diversity and complexity of the natural world, and may also have practical applications in horticulture and agriculture.