New Leaf

What's this Science Bite about?

Find out how plants transport water all the way up their stems to their leaves and flowers! You can try this fun experiment at home or in school.

Water helps a plant to transport nutrients around it, and helps support the plant standing up (plants go floppy if they don’t get enough water!) Water is taken in through the bottom of the plant, but how does it get all the way to the top?!?

Always remember to ask your parent or guardian to help you.

What you'll need

A beaker, water, food colouring and a celery leaf

  • A large beaker, mug or vase
  • Water
  • Food colouring - red or blue works well
  • A pair of scissors
  • Some plants - pick some of the following...
    - Celery sticks with the leaves still on
    - White flowers
    - Lettuce or other green leafed plants

How to do this experiment

  1. Prepare your plants!
    A beaker containing red coloured water with a green celery leaf in front of it
    Make sure you get an adult to help you with this part. Using scissors, cut off at least 2 cm from the bottom of each of the stems of the plants you have selected.

    Then pour some water into your container and add at least 5 drops of food colouring, so that the water becomes dark with the colouring.

  2. Water your plants! Place the cut plants into the container with coloured water.
    A beaker of coloured water with a celery leaf in it.
  3. Wait and Watch...

    Now leave your plants somewhere sunny - maybe on the windowsill.

    Coloured plant leafs in a bowl of coloured water.
    Check your plants after a few hours - what do you notice happening to them? How do you know the water has reached the top of the plant?

    Leave your plants overnight in the water - what do you notice about the colour after a longer period?

What should happen?

You should see that as you leave the plants in the water, the plant gradually turns more of the colour that you added into the water. If you used white flowers, you will see the flowers change colour, and if you used celery stick or another leaf plant, you will see their leaves change colour too!

Why does this happen?

Water travels up the stem of a plant through long thin tubes called Xylem. Water moves up these tubes through a process called Capillary Action. Molecules of water are attracted to molecules that make up the tube. Water molecules at the top are pulled up, and they attract the water molecules underneath them, and so pull them up the tube too!

A sponge also absorbs water by capillary action. All the gaps in a sponge act like thin tubes that pull in the water molecules around.

Find out more…

Water travels up the stem of a plant through long thin tubes called Xylem, by a process called Capillary Action. The water particles are attracted to the side of the tube by a process called adhesion and as a result of this affect the water is pulled up the xylem.

This water is used in the leaves for photo synthesis or is lost to the atmosphere by evaporation. This whole process is called transpiration.

A sponge also absorbs water by capillary action. All the gaps in a sponge act like thin tubes that pull in the water molecules around.

If you cut the stem of the celery you can see the coloured liquid in the Xylem. There are also tubes that bring glucose (the plants food that is made in the leaves by photosynthesis) down the stem but we can’t see these. They are called Pholem.

Curriculum Links

Biodiversity and Interdependance

SCN 1-03a/ 2-02a

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Glasgow Science Centre