How does water get up to the top of a plant?
Learn how to demonstrate transport in plants using felt pens and a stick of celery.
Water-soluble food colourings (no glycerol in the ingredients) or the ink from
inside a water-based (washable) felt pen can be used. You can break open a
cheap felt pen using a hammer, but place it in a plastic bag wrapped in
newspaper to avoid spattering the ink.
A felt pen contains plenty of ink for a number of demonstrations
You will need:
• a stick of celery
• a sharp knife
• a beaker
• some water-soluble food colouring, paint or ink
• a plate or tile.
For the extension activities, you also need:
• a ruler
• a stopwatch.
How to do it
Leave the stick of celery dipped in a small amount of
coloured solution for some time – a couple of hours
should be enough, but some dyes need longer.
Remove the celery and dab it dry.
Cut slices across the stem.
Can you see coloured spots?
How many slices have picked up the colour?
You can also cut along one of the coloured tubes to show
its shape up the stem.
Several sticks of celery set up for the
demonstration. Face paints did not work well:
other washable colourings may work: trial them
before using in class.
Experimental points
Take care with sharp knives.
Gloves are not needed but you might like to
protect your hands from staining.
After the activity, wrap the waste and place in
the normal refuse.
Do not eat stained celery.
How does water get up to the top of a plant? Results
Cutting along the stem: you can see how far the coloured water has
travelled.
How did it work?
If you sliced the stem, you cut across the xylem tubes which carry water and
nutrients up the stem to supply the whole plant.
Water travelled up the xylem, bringing the dissolved colouring with it.
Extension idea: If you cut at 1 cm intervals you can work out how
far the water travelled, and if you measure the time taken you can
work out its rate of movement.
Extension question: Can you estimate how long it would take for water to
reach the top of the plant? You will need to measure the height of the plant.
CLEAPSS® Draft T ransport in plants. ASE Birmingham 2014