Humans and other animals are very complex creatures. So let’s first consider plants. Plants seem to be simple examples of the way life works. You plant them in the ground, water them, and let the sun shine on them. Pretty soon, they grow, they bloom, and then they die. But inside a plant, there are processes happening that we don’t see — processes unlike anything else we encounter. Let’s begin to understand these processes with what everyone knows is the most important resource a plant can get: water.
How does water get from the ground to the leaves of a plant?
4 full glasses of water at room temperature Red, blue, green, and yellow food coloring 3 white carnations from a florist Sharp knife
Mix one color into each of your four glasses. The stronger the color of the water, the more effective the experiment will be. Place your first carnation into the glass of your choice. You may need to trim the stem if it’s too long. Place your second carnation into another glass. Take your final carnation and, with an adult’s help, slice the stem lengthwise so that it looks like two smaller stems, both of which remain attached to the flower. Place one half of the stem into your third glass of colored water and the other half into the fourth and final glass. Place the flowers out of the sunlight and wait a day or so. Then look at each of the flowers.
Through a process called capillary action, water travels up through the stems of plants until it reaches the outermost parts of the flowers. You saw this when the flower of each carnation turned the color of the water it was sitting in. Even more interesting is that the split stem produced a flower with both colors in it. You could easily repeat this experiment with other flowers and other colors to see if they behave in the same way. Celery stalks with the leaves on also work well in this experiment. capillary action: the process that allows water and other nutrients to move up from the ground to all parts of a plant.