Dispersal

DISPERSAL

•      Many plants scatter their seeds in order to ensure that they do not grow too close to one another.

•      The process by which the seeds are scattered away from the mother plant is called dispersal.

•      Nature has its own way of dispersal of seeds.

The ways by which dispersal of Seeds take Place:

A.    Dispersal by wind:

•      Seeds of certain plants are very light and have wings or hair on them.

•      These seeds are easily carried away by wind.

Dandelion

For example:

•      dandelion, sycamore, ash, bulrush, willow herb, thistle

B.   Dispersal by animals:

•      Seeds of plants are scattered by animals also.

•      Certain seeds have hooks, stiff hair, or spines, which help in their dispersal.

•      Animals and human beings eat some fruits and throw away the seeds, which grow into new plants.

Cockleburr

For example:

•      sunflower, date, raspberry, tamarind, sea grape, sea holly, cocklebur

C.   Dispersal by water:

•      Seeds of the plants are scattered by water.

•      Seeds of some plants are spongy or have a fibrous covering which helps them to float on water.

•      Water transports these seeds from one place to another.

Lotus

For example:

•      yellow water lily, lotus, mangrove, water mint, coconut, sea bean

D.   Dispersal by explosion:

•      Fruits of certain plants burst open when they are ripe, scattering the seeds in all directions.

Poppy

•      This mechanism of seed dispersal is called explosion.

For example:

•      viola, lathyrus, broom, poppy, pea, lupin, bean

BRAIN TEASERS

1. Montu planted seeds in the field. He provided sufficient water and nutrients to them. He threw the seeds very close to one another in the field. What do you think, will all the seeds be able to grow into a healthy plant?

Ans: No, all the seeds will not be able to grow into plants because of lack of space and nutrients.

2. In nature, seeds are dispersed by themselves. Sea current carried the coconut seeds away with it. (a) Some seeds got scattered on the wet soil near the coastal areas. (b) Some seeds were carried to very cold regions and some to the forest.  Which condition is favourable for coconut seeds to germinate and bear fruits?

Ans: The seeds which got scattered on the wet soil near coastal areas will germinate and bear fruits.

3. Sycamore seeds are carried away by the wind. If some seeds fell on the soil and some on the football ground. Which seeds will germinate?

Ans: The seeds that fell on the soil will germinate.

4. Tamarind seeds are carried away by some animals or birds. Some seeds fell in the jungle. Some fell in the kitchen garden. Some fell in water. At which place do you think the tamarind seeds will grow into a new plant?

Ans: In the Kitchen garden seeds will be able to germinate and will grow into a new plant.

5. If the seeds of bean and pea are not sown. How do they germinate? Is there any way by which their seeds can be disperse.

Ans: The dispersal of bean and pea seeds take place by explosion. When the seeds are scattered on the soil by themselves, they can germinate into new plants.

6. Sunflower is a shrub. The seed of the sunflower plant grows into a new sunflower plant if scattered properly on the soil. The seeds of sunflower are flown away by the wind. Will the seeds be able to germinate?

Ans: No, the seeds will not be able to germinate as their dispersal should be done by animals.