Sexual Reproduction in Flowering Plants

SEXUAL REPRODUCTION IN FLOWERING PLANTS:-

Plants reproduce sexually by producing male gametes in the form of pollen and female gametes in the form of eggs. The reproductive parts of angiosperms are located in the flower.

A flower comprises sepals, petals, stamens and carpels. Stamen and carpel are the reproductive parts of a flower Which contain germ cell.

-A unisexual flower contains either stamens or carpel. For e.g. papaya and watermelon are unisexual flowers.

-A bisexual flower contains stamens as well as carpels for example, hibiscus and mustard flowers are biusexual.

Stamen is the male reproductive part and it produces pollen grains. Carpel is present in the centre of the flower and is the female reproductive part. It consists of the ovary, style and stigma. The ovary is the swollen part at the bottom of the carpel. Ovary contains the female gametes in the form of eggs or ovules. The male germ cell produced by the pollen grains fuses with the female gamete present in the ovule. The fusion of germ cells or fertilization s the zygote which is capable of growing into a new plant.

The transfer of pollen grains from the anther to the stigma of the carpel is known as pollination. Two types of pollination are self pollination and cross pollination. Self pollination involves the transfer of pollen grains from anther to stigma of the same flower. Cross pollination involves the transfer of pollen grains from anther of one flower to the stigma of another flower. This transfer of pollen grains from one flower to another is achieved by agents like wind, water and animals.

After the pollen lands on the suitable stigma it has to reach the female germ cells which are in the ovary. For this a tube grows out of the pollen grain and travels through the style to reach the ovule. Inside the ovule the male germ cell fuses with the female germ cell and forms a zygote. This is known as fertilization.

After fertilization, the zygote divides repeatedly to form an embryo which resides inside the seed. The ovule develops into a seed. The ovary ripens to form a fruit. Meanwhile the petals, sepals, style, stigma may fall off . Seed inside the fruit encloses the embryo, the future plant. The seed containing the embryo develops into a seedling under appropriate conditions . This process is known as germination. The factors essential for germination are nutrients, water and poor temperature.

Seed has an embryo protected by reserve food materials in the form of cotyledons and also an outer covering called us seed coat.

After the pollen lands on the suitable stigma it has to reach the female germ cells which are in the ovary. For this a tube grows out of the pollen grain and travels through the style to reach the ovule. Inside the ovule the male germ cell fuses with the female germ cell and forms a zygote. This is known as fertilization.

After fertilization, the zygote divides repeatedly to form an embryo which resides inside the seed. The ovule develops into a seed. The ovary ripens to form a fruit. Meanwhile the petals, sepals, style, stigma may fall off . Seed inside the fruit encloses the embryo, the future plant. The seed containing the embryo develops into a seedling under appropriate conditions . This process is known as germination. The factors essential for germination are nutrients, water and poor temperature.

Seed has an embryo protected by reserve food materials in the form of cotyledons and also an outer covering called us seed coat.