Have you ever thought to yourself, “You know, this celery just isn’t colorful enough!”? I know I have, and guess what… you can make your celery as colorful as you want it! But why stop there – how about we also make some colorful carnations! By the way the earlier you start this one the better, as it will take a few hours for the experiment to work.
- Fresh Celery with the leaves
- White Carnation
- Knife (make sure you get a parent to help!)
- 2 Drinking Glasses
- Food Coloring
- Cut off about 2 cm from the bottom of the celery. (This will expose fresh celery stalk for the water to travel up).
- Fill one of your drinking glasses about half full with plain tap water. Add a couple of drops of food coloring to your water (Note: The more strongly colored your water, the more of a color change you will see).
- Put your celery stalk in the colored water and leave it out of the way somewhere (but make sure it has plenty of light). Come back to check it every hour or so. What did you see?
- Once the color has reached the leaves, (it will take a few hours) remove the stalk from the water and cut a small piece off the bottom of the celery stalk – what do you see?
- Cut the stalk lengthwise, exposing the interior of the celery. Do you see anything interesting?
- After you finish experimenting with your celery (or after you finish setting up the celery in the water initially) you can set up your carnation. The color changing carnation will work on the same principle as the celery stalk, but it’s much nicer to leave out on the table!
- Take a carnation and cut off the bottom 2 cm of the stem again, just like with the celery. Then use your knife to split the carnation stem up the middle about 2/3 of the way up.
- Fill 2 drinking glasses about half full with drinking water, and put a couple of drops of food coloring in each glass. Use a different color food coloring for each glass (just trust me). Again, the more color in your water, the more pigmented your flowers will be.
- Set your carnations off to the side where they will not be disturbed for a couple of hours. Check them after a few hours have passed – What happened!?
What’s Going On Here?
When plants make food for themselves (in a process called photosynthesis) they use energy from light, water from their roots, and a gas called Carbon Dioxide found in the air to build sugars. In order to take in this carbon dioxide the plant must open little holes on the bottoms of it’s leaves (called stomata), but in the process some of the water in the plant can escape. (Try leaving a separate stalk of celery in an empty glass for a few hours – what happened to it?) In order to replace the lost water, the plant has little tubes inside it’s stem that transport water up to the leaves from the roots.
When you placed the celery inside of the colored water, both the water and the food coloring were taken up those tubes and thecoloring was left behind in the leaves when the water evaporated through the stomata! If you cut the stem open length-wise you should have seen the tubes going all the way up from bottom to top, loaded up with colored water. The longer you leave the celery in the food coloring, the more pigmented it’s leaves will become. Do you think that any particular food coloring would work better than another? Why don’t you do an experiment and find out?
The carnation works in a similar fashion, with the tubes in the stem carrying the pigment up to the leaves and the flower of the plant. When the tubes go to the flower, they take the pigment with them, and because the flower was white,you were able to see the colors very easily! Now, you should have noticed that half of the flower was the color of one of your cups, while the other half was the color of the other! This is because the tubes do not mix – each one starts and ends in a very specific location, and since all of the tubes on one side of the cut went to one side of the flower, and vice versa, the flower now has two colors!
Now, on a more serious note, this experiment demonstrates why it is so important that we take care of the land around us, and why eating organic fruits and vegetables can be much healthier for you! Any pollutants that were in the water or the soil where the plant grew could make their way into the parts of the plant that we eat! YUCK!
DID YOU KNOW?
- A large tree can pump as much as 900 liters of water to it’s leaves a day!
- Evaporation of water from the leaves helps lower the temperature of the surrounding area by several degrees!
- Most of the cloud that cover the Tropical Rainforest in South America are produced by the plants that live there!