---
title: "Plants Around Us"
book: "Primary & Middle School Biology"
subject: biology
language: en
chapter: 3
exercises: 10
source: https://one-course.com/books/biology/1/en/chapter/3-plants-around-us
---

# Chapter 3 — Plants Around Us

A daisy in the lawn, moss on the wall, the big chestnut [tree](#def-g1-plants-around-us-tree) in the schoolyard: none of them will ever run away, yet they are all alive. [Plants](#def-g1-plants-around-us-plant) are the quiet [living things](https://one-course.com/books/biology/1/en/chapter/1-living-or-not-living#def-g1-living-or-not-living) — they are born, they feed, they grow, sometimes for hundreds of years, all without moving from their spot.

## 3.1 Plants are living things

**Definition 3.1 (Plant).**

A *plant* is a [living thing](https://one-course.com/books/biology/1/en/chapter/1-living-or-not-living#def-g1-living-or-not-living) that stays fixed in the ground and makes its own food, using light. Grass, daisies, tomato plants and [trees](#def-g1-plants-around-us-tree) are all plants. Most plants are green.

**Example 3.2 (The daisy is alive).**

Check the signs of life on a daisy: it was born from a seed; it feeds — with water from the soil and light from the sky; it grows; it makes seeds that become new daisies; it dies in the frost. All the signs are there. The daisy is as alive as the cat — it is just much quieter about it.

![Daisies in the lawn: born from seeds, feeding on light and water, quietly alive.](https://one-course.com/images/onecourse/chapters/biology-1/g1-plants-around-us/img-655f09f64e11.jpg)

*Daisies in the lawn: born from seeds, feeding on light and water, quietly alive.*

**Remark 3.3 (Alive without running).**

[Plants](#def-g1-plants-around-us-plant) do not walk, but they are not completely still. A sunflower turns to follow the light during the day, and a [plant](#def-g1-plants-around-us-plant) on a windowsill slowly leans toward the window. [Plants](#def-g1-plants-around-us-plant) move by *growing* — too slowly for our eyes, fast enough for a week’s watching.

## 3.2 The parts of a plant

**Definition 3.4 (Parts of a plant).**

A flowering [plant](#def-g1-plants-around-us-plant) has four main parts:

1. the *roots* , hidden in the soil, which hold the [plant](#def-g1-plants-around-us-plant) in place and drink water;
2. the *stem* , which stands the [plant](#def-g1-plants-around-us-plant) up and carries water to the leaves;
3. the *leaves* , flat and green, which catch the light;
4. the *flower* , which will make the seeds.

![The four parts of a flowering plant, shown pulled up whole: in the ground, the roots do their work out of sight, under the soil.](https://one-course.com/images/onecourse/chapters/biology-1/g1-plants-around-us/fig-7e402275bb36.svg)

*The four parts of a flowering [plant](#def-g1-plants-around-us-plant), shown pulled up whole: in the ground, the [roots](#def-g1-plants-around-us-parts) do their work out of sight, under the soil.*

**Example 3.5 (Pulling up a weed).**

Pull a weed gently out of loose, wet earth and you bring up the hidden part: a tuft of pale [roots](#def-g1-plants-around-us-parts), sometimes longer than the whole green [plant](#def-g1-plants-around-us-plant) above. Now the [plant](#def-g1-plants-around-us-plant) can be read from bottom to top: [roots](#def-g1-plants-around-us-parts), [stem](#def-g1-plants-around-us-parts), [leaves](#def-g1-plants-around-us-parts) — and, if you are lucky, a [flower](#def-g1-plants-around-us-parts).

**Definition 3.6 (Tree).**

A *tree* is a big [plant](#def-g1-plants-around-us-plant) whose [stem](#def-g1-plants-around-us-parts) is made of wood. The tree’s woody [stem](#def-g1-plants-around-us-parts) is called the *trunk*; it divides into *branches*, which carry the [leaves](#def-g1-plants-around-us-parts).

**Example 3.7 (The chestnut tree).**

The chestnut [tree](#def-g1-plants-around-us-tree) in the yard has the same plan as the daisy, but bigger and harder: [roots](#def-g1-plants-around-us-parts) under the ground, a trunk instead of a soft [stem](#def-g1-plants-around-us-parts), [branches](#def-g1-plants-around-us-tree) with thousands of [leaves](#def-g1-plants-around-us-parts), and in spring, [flowers](#def-g1-plants-around-us-parts). The daisy lives one year; the chestnut can live longer than a hundred.

## 3.3 What a plant needs

**Proposition 3.8 (The needs of a plant).**

To live and grow, a [plant](#def-g1-plants-around-us-plant) needs *water*, *light*, and a place for its [roots](#def-g1-plants-around-us-parts), usually *soil*. A [plant](#def-g1-plants-around-us-plant) kept in the dark, or never watered, wilts and dies.

**Proof.** *Admitted at this level.* ∎

**Example 3.9 (The forgotten plant).**

Forget to water the classroom [plant](#def-g1-plants-around-us-plant) before the holidays: its [leaves](#def-g1-plants-around-us-parts) hang down, soft and sad — it wilts. Water it, and a few hours later the [leaves](#def-g1-plants-around-us-parts) stand up again. Water was the missing need.

**Method 3.10 (Looking after a plant).**

1. Put the pot where daylight reaches it;
2. water the soil when it feels dry — not every hour, the [roots](#def-g1-plants-around-us-parts) also need air;
3. do not pull off the [leaves](#def-g1-plants-around-us-parts) : they are the [plant](#def-g1-plants-around-us-plant) ’s light catchers;
4. be patient: a [plant](#def-g1-plants-around-us-plant) answers in days, not in minutes.

**Remark 3.11 (Plants feed everyone).**

[Plants](#def-g1-plants-around-us-plant) matter to every [animal](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-animal). The snail eats the salad, the blackbird eats berries, we eat bread made from wheat — a [plant](#def-g1-plants-around-us-plant). Even the cat, who eats no salad, eats [animals](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-animal) that ate [plants](#def-g1-plants-around-us-plant). Without [plants](#def-g1-plants-around-us-plant), no one else would have anything to eat; a later chapter follows these food chains.

## 3.4 Exercises

**Exercise 3.1 ★.**

Name the four parts of a flowering [plant](#def-g1-plants-around-us-plant), from under the soil to the top.

**Solution of Exercise 3.1.**

[Roots](#def-g1-plants-around-us-parts) (under the soil), [stem](#def-g1-plants-around-us-parts), [leaves](#def-g1-plants-around-us-parts), [flower](#def-g1-plants-around-us-parts).

**Exercise 3.2 ★.**

Which part of the [plant](#def-g1-plants-around-us-plant): (a) drinks water from the soil? (b) catches the light? (c) will make the seeds? (d) holds the [plant](#def-g1-plants-around-us-plant) upright?

**Solution of Exercise 3.2.**

(a) The [roots](#def-g1-plants-around-us-parts). (b) The [leaves](#def-g1-plants-around-us-parts). (c) The [flower](#def-g1-plants-around-us-parts). (d) The [stem](#def-g1-plants-around-us-parts).

**Exercise 3.3 ★.**

The daisy never walks. Go through the signs of life and say why it is a [living thing](https://one-course.com/books/biology/1/en/chapter/1-living-or-not-living#def-g1-living-or-not-living) anyway.

**Solution of Exercise 3.3.**

It was born from a seed, it feeds (water from the soil, light from the sky), it grows, it makes seeds that become new daisies, and it dies one day. All the signs of life are there; walking is not one of them.

**Exercise 3.4 ★.**

What are the special names of the [tree](#def-g1-plants-around-us-tree)’s [stem](#def-g1-plants-around-us-parts) and of the parts that carry its [leaves](#def-g1-plants-around-us-parts)?

**Solution of Exercise 3.4.**

The [tree](#def-g1-plants-around-us-tree)’s [stem](#def-g1-plants-around-us-parts) is the trunk; the [leaves](#def-g1-plants-around-us-parts) are carried by the [branches](#def-g1-plants-around-us-tree).

**Exercise 3.5 ★.**

Give the three things a [plant](#def-g1-plants-around-us-plant) needs to live, from [Proposition 3.8](#prop-g1-plants-around-us-needs).

**Solution of Exercise 3.5.**

Water, light, and a place for its [roots](#def-g1-plants-around-us-parts) — usually soil.

**Exercise 3.6 ★.**

The classroom [plant](#def-g1-plants-around-us-plant) has soft, hanging [leaves](#def-g1-plants-around-us-parts). What has probably been forgotten? What will happen after it is given?

**Solution of Exercise 3.6.**

The watering. The [plant](#def-g1-plants-around-us-plant) has wilted for lack of water; a few hours after being watered, its [leaves](#def-g1-plants-around-us-parts) will stand up again.

**Exercise 3.7 ★.**

In what ways are the daisy and the chestnut [tree](#def-g1-plants-around-us-tree) the same? In what two ways are they different?

**Solution of Exercise 3.7.**

The same: both are [plants](#def-g1-plants-around-us-plant), with [roots](#def-g1-plants-around-us-parts), a [stem](#def-g1-plants-around-us-parts), [leaves](#def-g1-plants-around-us-parts) and [flowers](#def-g1-plants-around-us-parts), and both need water and light. Different: the [tree](#def-g1-plants-around-us-tree)’s [stem](#def-g1-plants-around-us-parts) is a woody trunk while the daisy’s [stem](#def-g1-plants-around-us-parts) is soft and green, and the [tree](#def-g1-plants-around-us-tree) is far bigger and lives far longer.

**Exercise 3.8 ★.**

Try it: put one bean [plant](#def-g1-plants-around-us-plant) (or cress pot) near the window and one in a dark cupboard, and water both. Look after one week. What difference do you expect, and which need explains it?

**Solution of Exercise 3.8.**

The window [plant](#def-g1-plants-around-us-plant) should be green and upright; the cupboard [plant](#def-g1-plants-around-us-plant) pale, stretched and weak, even though it was watered. The missing need is light — water alone is not enough.

**Exercise 3.9 ★★.**

Leo says: “[Plants](#def-g1-plants-around-us-plant) are not really alive — they never do anything.” Give him two things a [plant](#def-g1-plants-around-us-plant) does, slowly but surely, from [Remark 3.3](#rem-g1-plants-around-us-still) and [Example 3.2](#ex-g1-plants-around-us-daisy).

**Solution of Exercise 3.9.**

For example: the [plant](#def-g1-plants-around-us-plant) grows — taller week after week — and it turns or leans toward the light, like the sunflower following the day. Slow is not the same as doing nothing.

**Exercise 3.10 ★★.**

A carrot is orange and grows under the ground. Looking at the figure of the [plant](#def-g1-plants-around-us-plant)’s parts, which part of the carrot [plant](#def-g1-plants-around-us-plant) do you think we eat? What clue does “under the ground” give?

**Solution of Exercise 3.10.**

The [root](#def-g1-plants-around-us-parts). “Under the ground” is the [roots](#def-g1-plants-around-us-parts)’ place in the figure — the carrot we eat is a big, fat orange [root](#def-g1-plants-around-us-parts) that the [plant](#def-g1-plants-around-us-plant) filled with food.