25 Plant roots

We are learning how to:

• identify different types of plant roots

• describe the functions of a plant root water film covering soil particles and roots, also between particles water root hair root hair cell soil particle

The roots are the part of the plant that is in the soil. They absorb water containing dissolved minerals from the soil.

A plant, such as a pepper plant, might have a fibrous root that divides into thinner and thinner roots, or it may be more like a carrot and have a tap root, which is a large swollen root with smaller roots growing from it.

Plant roots are ideally suited to absorbing water from the soil. They divide many times so that there is a large surface area available for absorption.

Plant roots consist of plant root cells. Each cell has a root hair that grows out into the gaps between soil particles, increasing the surface area of the roots even more. Water containing minerals is absorbed through the root hairs.

Activity B 3.25.1

Examining roots

Here is what you need:

• recently germinated pea or bean plant

• hand lens

• legume plant

Here is what you should do:

1. Carefully remove a plant from a pot so that soil remains around the roots.

2. Look carefully at the roots. Notice how they are spread out to provide the plant with a firm anchor, and also to absorb water and nutrients from different parts of the soil. Notice how the roots divide a number of times to finally produce very thin root hairs.

3. Knock away some of the soil and examine the area immediately around the roots. Can you see any root hairs?

4. Make some drawings of the roots showing their different features.

5. [STEAM] The roots of a group of plants called legumes are associated with fixing or converting atmospheric nitrogen into nitrogenous compounds in the soil. Obtain a legume plant and draw its roots showing how they differ from other plant roots.

Check your understanding

1. Fig B 3.25.4 shows two different types of root system.

Key terms

fibrous root root that divides many times, producing a network of tiny roots tap root systemfibrous root system a) Which root stores more nutrients? b) In what ways are the root systems designed to gather water and nutrients efficiently? tap root large thick root swollen with food reserves root hair finger-like projection on a root cell, which increases its surface area for absorption