In this module, you will learn:
- the importance of seed dispersal
- recognise the different methods for seed dispersal
Resources to help you:
- Textbook: page 138 and 139
- Notebook: page 35 and 36
What happens after fertilisation?
After fertilisation, the flower develops into the fruit and the seed(s). The seed contains the embryo which will develop into a young plant but before that can happen it needs to be moved to a suitable place to grow.
Watch the video
Learn about different methods of dispersal
Source: https://www.youtube.com/watch?v=06sbmWAzoys
You can change the speed to 0.75x to make it easier to listen.
Why dispersal?
It is important for the dispersal of seed to be away from the parent plant.
This is to prevent overcrowding. Overcrowding means that too many plants are growing in a small amount of space. This is not healthy for the plants because when all the plants are close together, they are competing for nutrients, water and sunlight.
When a plant does not get enough nutrients, water or sunlight, it will not grow optimally and may even die.
Credit: @germanopoli via DepositPhotos
The methods of dispersal
There are four main methods of seed dispersal:
- wind dispersal
- water dispersal
- animal dispersal
- self-dispersal
Wind dispersal
Characteristics of a wind-dispersed fruit or seed
- they are light
- they have wing-like or parachute-like structures
- they can have hair like structures surrounding their seeds
Close up of a dandelion
Credit: @velkol via YayImages
A shorea fruit (meranti)
Credit: @Satakorn via YayImages
Dandelion seed getting carried by the wind
Credit: @Janetta via YayImages
Coconut husk has air trapped to allow it to float.
Credit: Lana_M via YayImages
The lotus pod floats on water.
Credit: @magann via DepositPhotos
Water Dispersal
Characteristics of a water-dispersed fruit or seed
- Fruits or seeds that can float on water
- Parent plants live near or on water.
The coconut has trapped air inside the husk giving it a density less that water. This allows it to float on water.
Animal Dispersal
Characteristics of a animal-dispersed fruit or seed
- Fruits that are fleshy and juicy
- Seeds with tough coats to protect from being digested
- Fruits or seeds with spikes or hooks to attach to animal fur or clothings
A girl eating a watermelon that contains seeds
Credit: @irchena via Twenty20
Grass seeds clinging on clothing
Credit: @denikeka30@gmail.com via DepositPhotos
A monkey eating from a fruit and throwing away the seeds.
Credit: @cloudyew via YayImages
Different self dispersal fruits
Source: https://www.youtube.com/watch?v=OB0P3mx_lxY
Self Dispersal
Characteristics of a self-dispersed fruit or seed
- seeds stored in pods
- fruit dries and explode
