Color Changing Carnations Where does the water go when a plant is watered? email to friend
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1. Fill each cup half full with water.
   
   
2. Add about 20-30 drops of food coloring to each cup of water. In this case, more food coloring is better!
   
   
3. Before placing any of the flowers in the colored water, have a adult trim the stem of each flower at an angle to create a fresh cut. For cut flowers, it is important for the stem tubes to be filled with water. If air gets in the tube no water can move up the stem. Many gardeners and florists cut stems under water so no air bubbles can get in to break the tube of water and make the flower wilt.
   
   
4. Place one freshly cut white carnation in each of the cups of colored water. Save the remaining two carnations for the next step. Make some predictions: Which color will be soaked up first? How long will it take?
   
   
5. This popular trick is called "Split Ends" and it requires some help from an adult. Have your adult helper use a sharp knife to slit the stem straight down the middle. Put each half of the stem into a cup of different colored water (try positioning the red and blue cups next to each other, for example). Make a few more predictions: Which color will be soaked up? Will the colors mix to make a new color? Just remember to keep the ends of the stem wet at all times and make fresh cuts on the ends.
   
   
6. You'll want to check back every few hours to see how things are progressing. It may take as much as 24 hours for the colored water to work its way up to the white petals. At the conclusion of your experiment, remember to examine the whole plant carefully including the stems, leaves, buds and petals to find every trace of color.

How does it work?

As you probably noticed, most plants have a "drinking" problem. Okay, in this case it's a good problem. Most plants "drink" water from the ground through their roots. The water travels up the stem of the plant into the leaves and flowers where it makes food. When a flower is cut, it no longer has it's roots, but the stem of the flower still "drinks" up the water and provides it to the leaves and flowers.

Okay, now it's time to get technical. There are two things that combine to move water through plants -- TRANSPIRATION and COHESION. Water evaporating from the leaves, buds and petals (TRANSPIRATION) pulls water up the stem of the plant. This works in the same way as sucking on a straw. Water that evaporates from the leaves "pulls" other water behind it up to fill the space left by the evaporating water, but instead of your mouth providing the suction it is due to evaporating water. This can happen because water is very sticky--to itself (called water COHESION) and because the tubes in the plant stem are very small (in a part of the plant called the XYLEM). This process is called CAPILLARY ACTION.

Coloring the water with food coloring does not harm the plant in any way but allows you to see the movement of water through the roots to the shoots. Splitting the stem simply proves that the tiny tubes in the stem run all the way from the stem to the petals of the flowers. Our unofficial tests indicated that the blue dye went up the carnations the fastest followed by the red dye and then the green dye.

Like colored dyes in this experiment, some chemicals that pollute our waters can get into the soil and ground water and contaminate our vegetables and plants growing in the soil. Some chemicals and pollutants, just like the color dyes, may travel up into the plant and affect its health or growth.