Plants Organizations

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 thar flower (fig.1.1)
In this way pollination is carried out by insects. Birds and other animals also take parti in the pollination.
A pollen tube arises from the pollen gairns. 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 forme 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 disapersed 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 thats 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 fibres. Seeds of sheesham are flat and very light in weight. Maple seeds have wings on the both sides (fig 1.2)

Dispersal by Water: 

The seeds of plants that grows in or near water are carried far away by water.
Lotus plants grow in the pools and ponds.
Their fruit fall in water when ripen and carried to a long distance by water currents. Lotus fruits is like a sponge and floats on the surface of water. Its seeds drops at the new places and grow into new plants.Coconut trees grow along the sea coast. Hair like fibres, present on coconut fruit, help it to float on water.
Its fruits flaots long distances along tides.
When it reaches some land mass, it grows into a new plants(fig 1.4)

Dispersal  by Animals and Men:

Men, monkeys, squirrels and birds eat juicy fruit. They take the fruit with them to distant places and throw away seeds after eating  the fruits. New plants grow from these seeds. Some fruits have hard and small seeds. These seeds are eaten alongwith fruit, for example guava. Such seeds are not digested.
If animals goes far away, they are excreted alongwith faeces. In this way, they are dispersed.
Some fruit have rough surface or bristles on them. They stick to clothes, feathers of birds and hair of animals and are carried to distant places where they fall and so are dispersed ( fig 1.5)