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 getting scattered far and wide and have a better chance of growing in a suitable place without over crowding. So, this is what we understand as seed dispersal. Let’s talk about more through this lesson.
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.
Examples of special features of seeds for dispersing seeds
|Sticky and have hooks||Wings||Hairy parachutes||Pods||Holes||Spongy layers of fibres||Spongy coverings|
Examples of seed dispersal by wind;
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
Examples of seed dispersal by water;
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
Examples of seed dispersal by animals;
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
Examples of seed dispersal by humans;