This experiment will show how essential the functions of stems are to plant growth.
• Food Coloring
• Jar, Plastic Cup or Test Tube
• A Flower (light colored-white carnation) or Celery Stalk (with leaves)
1. Fill the test tube with water (You can take plastic cup or jar or any bottle).
2. Add a few drops of food coloring to it.
3. Cut the end off the stem (stalk) of the flower.
4. Put a flower into each test tube, and leave them for the day. You can monitor the flowers to see when they start to change colour.
The colour of the flower gets changed within around 6 hours
Plants ‘drink’ water through their roots, and the water moves up the stem to the leaves and flowers. By slicing the stem open, you will be able to see that the capillaries have been coloured as well. Water moves upwards through the plant mainly by a difference in pressure – water evaporating from the leaves causes negative pressure, while water entering the roots via osmosis causes positive pressure. It works the same was as sucking up liquid through a straw.