To demonstrate how flowers get water from the ground
- Three white flowers (carnations work well)
- Three tall clear water glasses
- Food coloring (three different colors)
Fill the glasses about two-thirds full of water and add two to three drops of food coloring to each glass of water (one color per glass). Cut the stems of the flowers about four inches from the bottom. Put a flower in each glass and let them stand overnight.
The white flower will turn the color of the water it was standing in overnight. Plants need to drink water to live. The colored water is pulled up through the stems into the petals due to capillary action (the movement of water due to adhesion, cohesion, and surface tension). Capillary action occurs because the water molecules at the top are pulled up the tube (xylem). The water molecules below them are pulled to the top because of their attraction to the water molecules above them. This works in the same way as sucking on a straw.