Organization Of Plant and Fertilization

We have studied in the previous class that pollen grains are formed in the stamen. Which is the male part of the flower. the pollen grain are transferred to stigma of the carpel, the female part of the flower. the process of transfer of pollen grains is called Pollination.

Fertilization:

You might have seen that butterflies,honey bees and moths hover over flowers and fly one flower to another.Why do they do so? actually,they collect nectar(honey) from the flower. while they visit a flower, the pollen grains stick to their bodies. When they sit on another flower,pollen grains fall on the stigma of that flower (fig.1.1)

In this way pollination is carried out by insects. Birds and other animals also take parts in the pollination.

A pollen tube arises from the pollen grains. It passes through the style and reaches the overy where male reproductive cell of the pollen grains fuses with the female reproductive cell of the ovule. This process is know as fertilization.

As a result of fertilization, seed is form from the ovule and the ovary ripens into a fruit.

Dispersal of Seeds and Fruits:

When seeds and fruits have ripened, they drop from the plant. Plants needs light, water and air to live. If all seeds drops at the same place then only a few plants would be able to germinate and grow because all of them not get sufficient light, water and air. There is why the seeds are dispersed far and wide so that maximum number of new plants may be produced.

Air, water and animals helps in the dispersal of seeds.

Dispersal by Air:

The seeds that are dispersed by air are light in weight and small in size. They are carried by wind over long distance. For example sumbal, cotton and aak have hair like fibers. Seeds of sheesham are flat and very light in weight. Maple seeds have wings on the both sides.