You probably already know plants need water to grow. Maybe you have a garden in the summer, and have needed to water it if there wasn’t enough rain to keep the plants healthy. We can see what happens when plants don’t get enough water during a drought—an extended period when the water supply is low. During a drought, local crops often suffer.
Plants get the water they need from the soil in which they grow. But how does the water move from the plant’s roots in the soil to the other parts, like the stems and leaves? This movement of water takes place in the xylem (pronounced ZY-lum), vein-like tubes that run from the roots of the plant to the leaves and other parts. These tubes move water and other nutrients from the soil to the parts of the plant that need them.
Think of the xylem of the plant as a little like drinking straws. Plants naturally lose water through their leaves: During the day, small pores called stomata open on the leaf surface of the plant letting in nutrients from the air (like carbon dioxide).. This also allows some water to evaporate, which helps keep the plant cool, the same way your skin does when you sweat.
This evaporation of water through the stomata causes more water to be pulled upward through the xylem of the plant, similar to the way you pull water up a straw with your mouth.
We almost never get to see the xylem of the plants around us, because they are buried deep inside the plant. But we can make them much easier to see using food coloring, and a piece of celery!
TRY THIS!
Here’s what you’ll need:
1. 6 Stalks of celery, at least 6 inches long
2. 6 Drinking glasses
3. A 1-cup measuring cup
4. Water
5. Red or blue food coloring
6. A knife (have an adult help you with this!!)
7. A cutting board
8. Paper towels
9. A ruler
Here’s what to do:
1. Cut the pieces of celery so they are all the same length. Cut only the bottom (root) end, leaving any leaves at the top. Try to leave the stalks as long as possible!
2. Measure one cup of water into each of your six glasses.
3. Put 10 drops of food coloring into each glass.
4. Add a stalk of celery to each glass, the cut end submerged in the water.
5. After two hours, remove one stalk of celery, and dry it off with a paper towel. Take a look at the bottom of the stalk that was in the water. Do you see any color change? Cut the stalk in half from the bottom to the top (lengthwise), and using your ruler measure how far from the bottom end the dye has traveled. The small tubes that have changed color are the celery’s xylem!
6. Measure the water left in the glass. Write down how much is left.
7. Write down all your observations, like what color the celery is changing, and how far up the celery the dye has traveled!
8. Do this again after 4 hours, 12 hours, 24 hours, and 48 hours. Be sure to write down any changes you see in the celery, and how far the dye has traveled each time.
What happened to the dye? Why do you think this happened? Now that your experiment is done, how much water is left in the final glass? Is this what you expected?
What else can you do with your celery? What would happen if you changed the conditions, like putting the glasses with the celery in the sun, or in a dark cupboard? What about if you put the glass with the celery in a re-sealable plastic bag, and sealed it up during the experiment? Use your imagination, and try new things, but always be sure to write everything down, like what you are doing, and what you see during your experiment!
References for further reading:
1. McElrone, A J; Choat, B; Gambetta, G A; Brodersen, C R . (2013) Water Uptake and Transport in Vascular Plants. Nature Education Knowledge 4(5):6
2. Plants: Essential Processes, Water transport. SparkNotes. Retrieved 4-10-14. http://www.sparknotes.com/biology/plants/essentialprocesses/section1.rhtml
Licenses:
Creative Commons Attribution-Share Alike 3.0 Unported license: http://creativecommons.org/licenses/by-sa/3.0/legalcode
TRY THIS!
Here’s what you’ll need:
1. 6 Stalks of celery, at least 6 inches long
2. 6 Drinking glasses
3. A 1-cup measuring cup
4. Water
5. Red or blue food coloring
6. A knife (have an adult help you with this!!)
7. A cutting board
8. Paper towels
9. A ruler
Here’s what to do:
1. Cut the pieces of celery so they are all the same length. Cut only the bottom (root) end, leaving any leaves at the top. Try to leave the stalks as long as possible!
2. Measure one cup of water into each of your six glasses.
3. Put 10 drops of food coloring into each glass.
4. Add a stalk of celery to each glass, the cut end submerged in the water.
5. After two hours, remove one stalk of celery, and dry it off with a paper towel. Take a look at the bottom of the stalk that was in the water. Do you see any color change? Cut the stalk in half from the bottom to the top (lengthwise), and using your ruler measure how far from the bottom end the dye has traveled. The small tubes that have changed color are the celery’s xylem!
6. Measure the water left in the glass. Write down how much is left.
7. Write down all your observations, like what color the celery is changing, and how far up the celery the dye has traveled!
8. Do this again after 4 hours, 12 hours, 24 hours, and 48 hours. Be sure to write down any changes you see in the celery, and how far the dye has traveled each time.
What happened to the dye? Why do you think this happened? Now that your experiment is done, how much water is left in the final glass? Is this what you expected?
What else can you do with your celery? What would happen if you changed the conditions, like putting the glasses with the celery in the sun, or in a dark cupboard? What about if you put the glass with the celery in a re-sealable plastic bag, and sealed it up during the experiment? Use your imagination, and try new things, but always be sure to write everything down, like what you are doing, and what you see during your experiment!
References for further reading:
1. McElrone, A J; Choat, B; Gambetta, G A; Brodersen, C R . (2013) Water Uptake and Transport in Vascular Plants. Nature Education Knowledge 4(5):6
2. Plants: Essential Processes, Water transport. SparkNotes. Retrieved 4-10-14. http://www.sparknotes.com/biology/plants/essentialprocesses/section1.rhtml
Licenses:
Creative Commons Attribution-Share Alike 3.0 Unported license: http://creativecommons.org/licenses/by-sa/3.0/legalcode
