Back to: Botany 100 Level
Hello, my brilliant Afrilearn scholar! I hope you’re having a fantastic day! Have you ever wondered how a tiny seed grows into a big tree? Or why some fruits, like mangoes, have only one seed while others, like oranges, have many? Think about how the wind carries dandelion seeds or how birds eat fruits and drop the seeds far away.
Today, we’ll learn about how fruits and seeds develop, their structure, and the different ways seeds are dispersed. By the end of this lesson, you’ll understand why plants make fruits, how seeds travel, and why they don’t all grow in the same place.
Fruit And Seed Development: Formation, Structure, And Dispersal Mechanisms
Formation of Fruits and Seeds
After pollination and fertilisation, a flower changes into a fruit. Let’s go through the process:
Pollination – Pollen is transferred from the anther to the stigma.
Fertilisation – The male and female cells fuse inside the ovary.
Zygote formation – The fertilised ovule develops into a seed.
Fruit formation – The ovary grows and develops into a fruit, which protects the seed.
Example: In mango trees, fertilised flowers turn into mango fruits, and each mango contains a seed that can grow into a new mango tree!
Structure of Fruits and Seeds
1. Fruit Structure
A fruit is a mature ovary that contains seeds. Fruits can be:
Fleshy fruits – Soft and juicy (e.g., mango, pawpaw, orange).
Dry fruits – Hard and dry (e.g., groundnut, beans, maize).
Fruits have three main layers:
Epicarp (Outer layer): The skin of the fruit.
Mesocarp (Middle layer): The fleshy part in juicy fruits like mango.
Endocarp (Inner layer): Protects the seed (like the hard shell of a coconut).
2. Seed Structure
A seed is the baby plant (embryo) inside a protective cover. It has three main parts:
Seed coat (Testa): The outer covering that protects the seed.
Cotyledon: Stores food for the young plant.
Embryo: The tiny plant inside the seed that grows into a new plant.
Seeds can be monocots (one cotyledon, e.g., maize) or dicots (two cotyledons, e.g., beans).
Seed Dispersal: How Seeds Travel
Plants don’t want their seeds growing too close to them because they would compete for sunlight, water, and nutrients. So, they use different methods to spread their seeds far and wide.
1. Wind Dispersal
Seeds are light and have wings or fluffy structures that help them float in the air.
Examples: Cotton, dandelion, African mahogany.
Try this: Blow on a cotton seed and watch it float away!
2. Water Dispersal
Seeds have fibrous, waterproof coverings that help them float on water.
Examples: Coconut, water lily.
Example: A coconut falls into a river, floats to another island, and grows into a new coconut tree!
3. Animal Dispersal
Animals eat fleshy fruits and drop the seeds elsewhere.
Some seeds stick to animal fur and travel to new locations.
Examples: Mango, pawpaw, pear.
Fun fact: Birds eat fruits like cherry, and the seeds pass through their digestive system before being dropped elsewhere!
4. Explosive/Mechanical Dispersal
Some fruits burst open and scatter their seeds far away.
Examples: Okra, pride of Barbados.
Analogy: Imagine a balloon filled with air popping and sending bits flying everywhere—that’s how some plants scatter their seeds!
Why is Fruit and Seed Dispersal Important?
Prevents overcrowding – Seeds spread out and have more space to grow.
Ensures survival – If all seeds stayed in one place, many would die.
Helps plants colonise new areas – Seeds can travel far and grow in different environments.
Provides food for animals – Many animals rely on fruits and seeds for survival.
Without seed dispersal, forests wouldn’t spread, and we wouldn’t have as many different plants on Earth!
Summary
After fertilisation, the ovule develops into a seed, and the ovary becomes a fruit.
Fruits protect seeds and help in seed dispersal.
Seeds have a testa (coat), cotyledon (food store), and embryo (baby plant).
Seeds are dispersed by wind, water, animals, and explosive mechanisms.
Dispersal helps plants spread, survive, and grow in new areas.
Evaluation
- What happens to a flower after fertilisation?
- Name the three main parts of a seed.
- Give two examples of fruits dispersed by wind.
- How do animals help in seed dispersal?
- Why is seed dispersal important for plants?
You are doing an amazing job! Just like seeds travel and grow into big trees, your knowledge is growing stronger every day! Keep learning, keep exploring, and see you in the next exciting lesson!
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