The reproductive part of the plant is called the flower. Flowers are considered embryological and morphological marvels by most biologists.
The various parts of a flower my categorized into two classes - Vegetative and reproductive.
1. Vegetative parts: The vegetative parts of the flower are the ones that do not participate in the reproduction process. However, they perform other functions, such as attracting pollinating agents and protecting the buds.
Sepals and Petals are the vegetative parts of a flower.
2. Reproductive parts: The reproductive parts of the flower are the ones that participate in sexual reproduction, thereby leading to fruit formation.
Stamen is the male reproductive organ, whereas the pistil is the female reproductive organ.
Sepals are the outermost parts of the flower. They are small, green in colour, and are found below the buds. The primary function of sepals is to protect the rising bud. Sepals may be fused or separate.
Petals are the most colourful parts of the flower. Petals occur in different colours ranging from dark blue & black to pale white. The primary function of petals is to attracting pollinating agents such as insects, honey bees, and birds.
Stamen is the male reproductive part of the flower. The stamen is otherwise called androecium. A typical stamen consists of two parts - anther and filament.
The anther is generally a bilobed structure present at the terminal end of a flower. Each lobe of the anther consists of two thecae, i.e. dithecous. This tetragonal anther consists of 4 microsporangia, which further develop into pollen grains. The filament is a long, thin, and slender stalk whose proximal end is attached to petals or thallus. The length and number of stamens present in flowers differ from one species to another.
The pistil is the female reproductive part of the flower. It is otherwise called gynoecium. A typical pistil consists of three parts - stigma, style, and ovary.
Stigma is the recipient of pollen grains. Style is a long, thin, and slender part present below the stigma. The style leads to the ovary. The ovary is the bulged part of the female reproductive part.
The ovary consists of the placenta and ovules. The ovary is the part where fertilization of male and female gametes takes place. Seed and endosperm formation takes place in the ovary. The number of ovules present in the ovary differs from one species to another. For example, the ovary of wheat has one ovule, whereas papaya has many ovules.
Apart from the vegetative and reproductive parts, the flower has specialized structures called whorls. The whorls together form the radial arrangement of a flower. The four whorls seen in a flower are calyx, corolla, stamens, and carpels.
The two types of flowers are unisexual and bisexual.
Unisexual flower - A flower consisting of any one of the reproductive organs, i.e. either stamen or pistil, is called a unisexual flower.
Bisexual flower - A flower consisting of both the reproductive organs, i.e. stamen and pistil, is called a bisexual flower.