If all seeds of a plant fall under the parent plant they will grow crowded together and many will die because of lack of space or air, water, sunlight and minerals. Therefore it is better seeds get scattered far and wide and have better chance of growing in a suitable place without over crowding.
The scattering or spreading of seeds to different places is called seed dispersal.
1) Some seeds are sticky and have hooks.
2) Some seeds have wings.
3) Some seeds have hairy parachutes.
4) Some seeds are in pods.
5) Some seeds have small holes in them.
6) Some seeds have spongy layers of fibres around them.
7) Some seeds have smaller spongy coverings.
Special features in seeds for seed dispersal
|Sticky and have hooks||Wings||Hairy parachutes||Pods||Holes||Spongy layers of fibres||Spongy coverings|
Seeds which have wings and hairy parachutes on them are carried by the wind.
E.g. – sycamore, ash, maple, lime, dandelion and thistle
When pods dry, they split open suddenly and shooting the seeds away from the parent plant and this is easy when the wind is there.
E.g. – peas, lupins, laburnum and gorse
Some seeds have small holes in them, so they are very light in weight. When the wind rocks the plant, the seeds are scattered as if from a pepper pot.
E.g. – poppy and orchid fruits
Some seeds have spongy layers of fibres around them. These can trap air so the seeds can float.
These seeds can travel, sometimes for hundreds of kilometers, from one island to another.
E.g. – Coconut
Some seeds have smaller spongy coverings which lets them float in lakes and rivers.
E.g. – water lilies, alder trees
Brightly coloured and juicy fruits are often eaten by animals like birds. The hard seeds inside these fruits pass out of the animal’s body in its droppings.
E.g. – blackberries, strawberries, raspberries and gooseberries
The seeds may finish up a long way from where they were first eaten.
Animals like squirrels and jays bury some nuts, ready to eat later. These animals often forget where they have hidden their food, and some of these seeds can grow.
Some seeds and fruits have hooks that catch on the fur or feathers of animals or on people’s clothes. If the seeds eventually drop off on the soil, they may grow.
E.g. – goosegrass, burdock, wood avens
May 4, 2013