Every living thing needs to produce more of its kind so that its species does not disappear from the earth. The process by which living things achieve this end is known as reproduction. In plants, flowers help in reproduction, which results in seed formation. The colour and fragrance of flowers attract birds and insects those bring about pollination--the first step towards reproduction. The parts of plants are arranged in concentric circles.
Structurally, sepals form the outermost circle of a flower. These are green in colour and look like little leaves. The sepals cover the bud and protect the inner parts from damage. The part of the flower that the sepals form is called the calyx.
Petals are most visible, brightly coloured part of a flower. They are arranged in a circle just inside the sepals. Petals attract pollinators so that they visit the flower and transfer pollen from the male parts of the flower to the stigma of the female part of the flower. This transfer of the pollen grain is known as pollination. There are various agents of pollination such as wind, water, insects and animals. The part of the plant formed by the petals is called the corolla.
The male parts form the next circle just inside the petals. Each male part is known as a stamen. Each stamen consists of hairlike structure called the filament, which is attached on one end to the flower. On its free end, the filament contains sacs called the pollen sacs or anthers that contain pollen grains. The pollen grains need to reach the egg in the female part of a flower to cause reproduction. There may be many stamens in a flower that are collectively known as the androecium.
This is the innermost circle in a flower. It is scientific name is gynaeceum. However, it is more commonly known as the pistil. A pistil has a stigma, style and an ovary. The stigma is the uppermost part of a pistil. It is a sticky bulb or flat platform-like structure. It is on this bulb that the pollen grains from another flower are deposited. Below the stigma is the tubelike style that leads to the ovary. Eggs are present in the ovary.