[Biology Class Notes] on Inflorescence and Flowers Pdf for EXAM

“Inflorescence refers to the arrangement of flowers on the floral axis.”

What is Inflorescence?

An important part of a plant is the flower, which is designed for reproduction. In addition, it is an important component of bouquets, decorations, celebrations, gardens, and rituals. Its beauty and fragrance make it the most attractive part of the whole plant.

The Structure of Inflorescence

The peduncle is the main stalk that sustains the whole inflorescence, whereas the rachis is the branch that holds it. The stalk that bears each flower is called a pedicel. Further, each flower in an inflorescence is referred to as a floret. A fruiting inflorescence is also known as an infructescence. Solitary flowers, on the other hand, don’t always occur in inflorescences; those that occur on stems individually are known as solitary flowers.

 

We will discuss inflorescence and the different types of inflorescence.

Types of Inflorescence

Depending on the kind of plant, flowers can be single or multiple. As defined by a botanical dictionary, an inflorescence is a cluster of flowers arranged along a floral axis. Inflorescences come in two types: Racemose and Cymose.

 

The Racemose Inflorescence

An inflorescence with this kind of flowering branches along its floral axis laterally. There is an acropetal pattern in this case because the floral axis keeps growing.

The Cymose Inflorescence

It is the flower that terminates each floral axis in this type of inflorescence. Cymose inflorescences have an inflorescence dominated by basipetal flowers.

 

The Compound Inflorescence

Racemose or cymose branches occur on the main axis.

 

Cyathium

An oval cup-shaped structure containing nectar-producing glands is present. Within the cup-shaped structure, there is a female flower. The female flower is surrounded by a number of male flowers.

 Verticillaster

This is a condensed form of a dichasial cyme with a cluster of sessile and sub-sessile flowers.

Hypanthodium

An apical opening protected by scales forms the hollow cavity of the receptacle.

What are the Different Types of Flowers?

As we know, a flower constitutes the reproductive system of a plant. As the reproductive part, it ensures the continuance of a species of plant by the process called reproduction.

As we have already studied, a flower makes up for an especially important part of a plant. Be it biological or in the way of appearance. As for the biological role, it helps in the birth of offspring and the continuity of a plant species. This process is known as reproduction. 

A flower is made up of two organs, which are known as the two accessory organs, respectively called the calyx and corolla, and there are two reproductive organs, namely, androecium and gynoecium. These 4 whorls consisting of the accessory organs and the reproductive organs are set up in the formation of a stalk known as the receptacle or the thalamus. 

A flower can be classified into several groups on the basis of its number and the presentation of its whorls, symmetry, floral appendages, among many other things. On the basis of the presence of the number of whorls, a flower can be categorized as bisexual or unisexual. A unisexual flower is made up of the calyx, corolla, and androecium or gynoecium whereas, a bisexual flower, on the other hand, is composed of all the four whorls present i. e, the calyx, corolla, androecium, and gynoecium. 

A flower can be categorized into the following- hypogynous, perigynous, and epigynous categories on the basis of the arrangement of the three whorls, namely, calyx, corolla, and androecium according to the ovary on the receptacle.

Various Types of Flowers

A flower is a plant’s reproductive system. During the process of reproduction, it ensures the survival of a species of plant.

Floral organs include calyxes and corollas as well as androecium and gynoecium, which are reproductive organs. There are four whorls on a stalk called the receptacle (thalamus).

 

According to the number and arrangement of whorls, symmetry, floral appendages, etc., flowers can be classified into numerous categories. A flower can be unisexual or bisexual based on the number of whorls. Unisexual flowers consist of the calyx, corolla, and androecium, or gynoecium, whereas bisexual flowers have all four whorls present.

 

There are three classifications of flowers based on the arrangement of three whorls- the calyx, the corolla, and the androecium- in relation to the ovary.

Hypogynous

The ovary is placed above the other three whorls in a Hypogynous flower. Normally, the ovary is located high on the thalamus, while other parts are located below it, for example, tomato, tulip, brinjal, etc.

 

Perigynous

An ovary is located at the center of a perigynous flower, and all four whorls are approximately the same height. The ovary is half superior/inferior in this case, for example, rose, peach, cherry, etc.

 

Epigynous

The ovary is below the other three parts of epigynous flowers. The thalamus holds the ovary within it and the remaining three whorls are found above it, such as in daffodils, cucumbers, etc.