With the coming of spring the days get longer, the air gets warmer and the birds begin to sing. As you look around, you see many changes taking place but the most stunning transformation has to be in the plants. Almost magically, barren branches start to bud, brown grass turns green, and tiny little shoots push up through the soil. How does this happen? Does mother nature send plants a wake up call?
Well, in a sense, yes. But one way that plants awaken is with water. In fact, you could say that when the sap starts flowing, it's keen to be green! How does water move around in plants? Do the leaves pull it up, or are their other forces at play?
Here's a challenge for you that lets you get to the bottom of how water gets to the top.
Here's what you'll need to play along:
- 2 large glasses of water
- Red food coloring
- 2 fresh stalks of celery with leaves
- A spoon
- A plastic knife
Step 1: Put two or three drops of food coloring in each glass of water and mix them up with the spoon.
Step 2: Take one celery stalk and remove all the leaves from it. Leave the other alone.
Step 3: Use the knife to cut about 1 centimeter off the bottom of each stalk and place each stalk in one of the glasses with the red water.
Step 4: Put the two glasses side by side in direct sunlight (or under a lamp) and allow them to sit for about 24 hours.
Okay, so here's the challenge question: Which stalk of celery do you think will "drink up" the most water, the one with leaves or the one without? Before starting the experiment, write your predictions. After you've let the celery sit for 24 hours, cut off the tops of the celery to see if the inside is dyed red. Do leaves help to pull up the water, or does it get through the plant by some other means? I know you're "dying" to find out, so get busy and make your predications.
Notes to Teachers
Curriculum Focus: Science/Plant Biology/Water movement in plant growth
- Using food coloring, track the movement of water through two celery stalks — one with and one without leaves. Observe the path that water takes to get to a leaf.
- Predict how leaves affect plants' absorption of water.
- Observe the capillary action in plants.
For more information on plants, try these websites:
Welcome to Missouri Botanical Garden
The Missouri Botanical Garden's site offers extensive information on different biomes and ecosystems and their plants, from the rain forest to the grasslands, the desert to the wetlands.
University of Wisconsin-Madison Botanical Garden
Access various families of plants and view pictures of each.