Sexual reproduction is the type of reproduction that involves two different parents that belong to the opposite sex. This type of reproduction is seen in both plants and animals. In plants, sexual reproduction occurs in flowering plants.
A flower is the sexual reproductive organ in plants. Flowers are often the most attractive structures of a plant. The flower’s anatomy can be divided into the following layers:
Calyx – These are green petal-like structures that are found right above the base of the flower called the receptacle. The calyx is formed of sepals. Their main function is to protect the flower while it is still in the bud stage.
Corolla – Corolla is the collective name given to the petals which are colorful parts of the flower. The petals of different flowers are found in different color and in addition, most of the times they are fragrant as well. It is the petals that attract the pollinating agents to the flower. The corolla is located above the calyx layer.
Androecium – The androecium is the male reproductive part of a flower. It is considered the third whorl in a flower. The androecium is the name given to a group of stamens. Each stamen is made up of a filament and anther at the top of it. The anthers are lobed structures that produce pollen which contains the male gamete.
Gynoecium – The gynoecium is the female reproductive organ in a flower. It is composed of the stigma, style, and ovary. The style is a slender filament on top of which lies the stigma which functions to hold transferred pollen grains. Once the pollen lands on the stigma, it is passed downwards through the style to the ovary. The ovary is lobed and consists of ovules which contain the female gamete.
The pollen grains and ovules by themselves cannot travel from one place to another. There are other factors such as wind, water, or animals that enable the pollen grains to travel to reach the stigma of the same or another flower. The process by which pollen grains are transferred from the anthers of one flower to the stigma of the same or another flower is known as pollination.
Once the pollen grains carrying the male gamete reaches the stigma of the same or different flower, it is transported downwards via a pollen tube that arises from the pollen grain to reach the ovary. The ovary is present at the base of the flower and is lobed. These lobes contain the ovules carrying the female gamete.
The male gamete from the pollen now fuses with the female gamete in the ovule to form a zygote. This zygote undergoes cell division to form an embryo. Once the embryo starts developing, the ovary develops into the fruit, the other structures like the calyx and corolla fall off. The embryo becomes the seed which has the potential to give rise to a new plant.
