Plants Around Us
Primary 3 · Science and Elementary Technology
Plants Around Us
Lesson 1 of 3
13 min
Let's begin
Behind her classroom, Mutesi pulled a small weed out of the ground. She had to tug hard. When it finally came out, wet soil dropped off the bottom of it.
She held it up. "It has little strings down here," she said, "and a stalk, and green flags at the top."
Mutesi was right. A plant is not just one thing. It is built from parts, and every part has a job to do. Today you will learn the five parts, and you will learn what each one does for the plant.
If you can, go outside and pull up one small weed. Shake the soil off it. Hold it so the strings are at the bottom and the green part is at the top.
Now look at it slowly, from the bottom up. That is the order we will use.
Remember how hard Mutesi had to tug? Something was holding that weed down.
The thin strings at the bottom are the roots. They spread out into the soil and grip it, like your fingers gripping a rope. That is why a healthy plant is hard to pull out.
The roots do a second job too. They drink. Water sits in the soil between the tiny bits of earth, and the roots suck it up. Mixed in that water are tiny bits of food from the soil. We call them mineral salts.
Here is the proof: pull a plant out and leave it lying on the ground. By tomorrow it is floppy and dry. Its roots are no longer in the soil, so it cannot drink.
So the roots have two jobs: hold the plant in the soil, and drink water from the soil.
Push a bean plant gently to one side. Let go. It stands back up. Something inside it is strong.
That stalk is the stem. It holds the plant up, the way your legs hold you up. Because it holds the plant up, the leaves can reach the sunlight instead of lying in the mud.
Now cut across a banana stem. It is wet inside. Why? Because the stem is also a pipe. Water that the roots drank is travelling up the stem, all the way to the leaves.
On a bean plant the stem is thin and green. On a big avocado tree the stem is thick and hard, and we give it a special name: the trunk. A trunk is still a stem. It is just a very big one.
Leaves are flat, they are wide, and they grow up high where nothing shades them. That is not an accident.
Leaves make the plant's food. To do it, a leaf needs three things: sunlight falling on it, water coming up the stem, and air touching it.
A plant cannot walk to the market and buy food with Frw. Its leaves cook its food for it, using the sun. That is why leaves are flat and wide: a flat leaf catches lots of sunlight, the way a wide basin catches lots of rain.
Leaves come in every size. A banana leaf is longer than your arm. A bean leaf is smaller than your hand. Both are leaves, and both do the same job.
Watch one bean plant for a few weeks. First, small white flowers open on the stem. A week later, those flowers dry up and drop off.
Now look carefully at the exact spot where a flower used to be. A tiny green bean pod is growing there.
That tells you what a flower is for. The flower makes the seeds. No flower, no seeds. No seeds, no new plants.
Open that bean pod. Inside, in a neat row, sit the beans. Those beans are the seeds.
The pod itself is the fruit. A fruit is the box that grows around the seeds and keeps them safe.
Cut a tomato: seeds inside. Cut a passion fruit: seeds inside. Cut an avocado: one big seed inside. Tomato, passion fruit and avocado are all fruits, because each one is holding seeds.
Umutoni has a tomato plant in a tin outside her door. Let us go through it, bottom to top, and give each part its job.
| What she sees | Its name | Its job |
|---|---|---|
| Thin brown strings down in the soil | Roots | Hold the plant in the soil, and drink water |
| A green stalk standing up | Stem | Holds the plant up, and carries water to the leaves |
| Flat green blades on the sides | Leaves | Make the plant's food, using sunlight |
| Small yellow blooms | Flower | Makes the seeds |
| A round red tomato | Fruit | Covers the seeds and keeps them safe |
Five parts. Five jobs. Every flowering plant you meet is built the same way.
Your supper tonight is on your plate. Each thing on it is a different part of a plant. Let us work them out one by one.
You did not memorise those answers. You worked them out from the job each part does. That is real science.
Tip
Point and say it, from the bottom up
"Roots drink. Stem holds. Leaves cook. Flower makes seeds. Fruit keeps them safe."
Go to a real plant, touch each part with your finger, and say its line out loud. After three plants you will never forget it.
Think about each one first, then tap Show answer to check.
A big storm shakes a mango tree all night, but in the morning it is still standing. Which part kept it in the ground?
Answer: the roots. They spread out into the soil and grip it, so the wind cannot lift the tree away.
Gatete cuts through a banana stem and finds it is wet inside. Why is there water inside a stem?
Answer: because the stem is a pipe. The roots drank that water from the soil, and the stem is carrying it up to the leaves.
Keza leaves a small plant in a dark cupboard for two weeks. Which part of it cannot do its job in there?
Answer: the leaves. Leaves make food using sunlight. In a dark cupboard there is no sunlight, so they cannot cook any food.
You are eating a carrot and your friend is eating cabbage. Which plant part is each of you eating?
Answer: you are eating a root, and your friend is eating leaves. The carrot grew under the soil and drank water. Cabbage is a ball of flat green leaves.
Byiringiro cuts open a passion fruit and finds it full of small black seeds. Which part of the plant made those seeds in the first place?
Answer: the flower. The flower makes the seeds. Then the fruit grows around them, in the very place where the flower was.
What you learned today
Quick check
Match each plant part to its job.
Tap one on the left, then its partner on the right.
