Plants love water as much as vampires love blood. Although they don’t have long thin fangs, they’ve developed a great system for pulling water up through their trunks and stems to their highest leaves using capillary action.
The kids and I demonstrated how to make them on Kare11 Sunrise news last week. Click here to watch.
Make a vegetable vampire and watch capillary action move colored water through the cabbage creature you created.
To make a leafy vampire, you’ll need:
-head of fresh napa cabbage
-2 large cups, jars or plasticware containers large enough to hold the base of ½ of your cabbage
-fruits and veggies to use as eyes and eyebrows on your monster
-rubber bands or string
First, fill your two containers ¾ of the way to the top with warm (not hot) water.
Add 10 or more drops of blue food coloring to one container and 10 or more drops of red food coloring to the other .
With a sharp knife, cut the cabbage in half vertically, from the bottom up, leaving the top 10cm or so intact, so the two pieces are still attached at the crown. If possible, try to cut down the middle of one of the big leaves.
Use rubber bands to secure the bottoms of each side of the cabbage and make a fresh cut at the bottom, a few cm up from the old cut.
Put one half of the base of your cabbage in the red water, and the other half in the blue water.
Decorate your two “vampires” with eyes and spooky eyebrows made from olives and peppers (or whatever you have in the refrigerator.) Secure the decorations with toothpick.
Keep an eye on your cabbage to see how much colored water it’s drinking. Your vegetable vampire will have to drink for 24-48 hours for the best results.
Plants survive by drawing nutrients dissolved in water up into their stems, stalks, trunks, branches and leaves.
Capillary action is the main force that allows the movement of water up into plants. In a narrow tube, on a surface that attracts water, the attraction between the surface and water, coupled with the attraction of the water molecules to each other, pulls water up. Plants are composed of huge numbers of tube-shaped cells that take advantage of these physical forces.
In this experiment, you can see colored water being taken up, via capillary action, into your cabbage.
Imagine how high the water in giant redwoods has to travel to reach the leaves at the top. In very tall trees, a process called transpiration helps the water overcome the forces of gravity. Here’s a transpiration experiment you can try at home.