Adaptations of Plant Leaves

Adaptations of plant leaves

Students’ Sheet

Plants and animals have specific features that help them to survive in their environment. In this activity you will investigate a selection of plant leaves to discover how they are adapted to deter herbivores.

Be careful – leaves can sting and scratch! Use gloves to handle poisonous or sharp leaves.

Part 1

Look at the leaves of some common plants. Either you will look at real leaves, or you will use the photo sheet.

Are there any obvious ways that the leaves are adapted to deter herbivores? Fill in the ‘Plant Adaptations’ table below.

Not all adaptations are immediately visible. In the following parts of this activity, you will decide if any of the leaves have other adaptations.

Plant Adaptations table

Use your findings to complete the table by matching each plant with its adaptations.

Leaf / Has sharp prickles or spines / Has stings / Contains acid / Other
Holly
Ivy
Geranium
Grass
Nettle
Dock
Thistle

Questions

Name a plant with prickles……………………………………………………….

How does this adaptation help the plant to survive? ......

......

…………………………………………………………………………………....

………………………………………………………………………………………..

A geranium has very soft leaves. What adaptation does it have to deter herbivores? ......

………………………………………………………………………………………..

…………………………………………………………………………………………

………………………………………………………………………………………..

Why does the nettle have hairs/stings? …………………………………………..

…………………………………………………………………………………………

…………………………………………………………………………………………

Extension: Grass does not have sharp spines, stings or contain chemicals to deter herbivores. What adaptations does it have to help it survive rather than being destroyed by grazing animals?

Part 2 - Investigating the pH of plant material

In this part of the activity, you will look for some of the hidden adaptations of plant leaves which are not visible in the photos.

Apparatus

·  gloves

·  Universal Indicator and colour chart

·  25cm3 measuring cylinder

·  mortar and pestle

·  Small filter funnels

·  Cotton wool

·  Test tubes and rack

·  Balance

·  Selection of leaves to include holly, ivy, geranium, nettle, thistle, grass, dock

Method

1.  Prepare dilute Universal Indicator solution by measuring 2cm3 standard Universal Indicator and diluting to 25cm3 with tap water.

2.  Take 1g of leaf (one large geranium leaf or ivy leaf weighs about 1g).

3.  Rip into pieces and grind well in a mortar and pestle with 4cm3 of dilute Universal Indicator.

4.  Prepare a filter by placing a small plug of cotton wool in a small filter funnel.

5.  Filter the contents of the mortar into a test tube and determine the pH by comparison with a colour chart.

6.  Repeat for different leaves. Use a clean filter each time or change the cotton wool and wash the funnel between samples.

Record your results in a suitable table.

If the plant contains acid, fill this in on the ‘Plant Adaptations’ table above.

Part 3: Investigating Nettle Stings and Dock Leaves

Stinging nettles have developed stinging cells as an adaptation to deter herbivores from eating them. The plants contain long, thin, hollow hairs that cover the majority of the stem and the underside of the leaves. These hairs contain stinging chemicals.

Stinging hairs on a nettle leaf

In this activity you will investigate the stings in more detail.

Equipment

·  gloves

·  microscope

·  slides

·  plastic cover slips (small pieces of clear plastic such as acetate can be used if plastic cover slips are not available)

·  Universal Indicator solution

·  Universal Indicator paper

·  nettle leaves

·  dock leaves

·  equipment for pH testing, as in Part 2 (unless you have already tested the pH of dock leaves)

Method

1.  Look at a piece of a nettle leaf under the microscope – you should be able to see the stings as hollow hairs containing a colourless liquid.

2.  Put a drop of Universal Indicator solution onto the piece of nettle leaf on the slide and lay another slide on top.

3.  Press the slides together to break open some of the stings.

4.  You should see a pink colour developing around the spines after you press down on the top slide. What does this tell you about the liquid inside the spines?

5.  Take a fresh piece of nettle leaf and place it with the underside against a piece of damp Universal Indicator paper.

6.  Place a plastic cover slip on the leaf and press down to break some of the stings.

7.  You should see yellow spots on the paper where stings broke open. What does this tell you about the liquid inside the stings?

A piece of damp universal indicator paper that has been pressed against a nettle leaf. Yellow spots show where acid has been released from the stings.

From these experiments we can see that the stings contain acid.

Dock leaves are a traditional remedy to relieve the pain of nettle stings.

1.  If nettle stings are acidic, what would you expect the pH of dock leaves to be?

2.  Refer to your results from the earlier experiment or measure the pH of a dock leaf using the method described above. What is the pH of a dock leaf?

3.  How then can a dock leaf help with a nettle sting? (Think about what you know about other allergic reactions caused by plants, such as hayfever, and how they are controlled).

Science & Plants for Schools: www.saps.org.uk

Adaptations of plant leaves – student sheet: p. 2

This resource may be photocopied for educational use. Revised 2012.