Leaves contain different pigments, which give them their color. The color in leaves depends on the presence or absence of chlorophyll (green), carotenoids (yellow-red) and anthocyanins (red-purple). By the end of summer, the production of chlorophyll molecules slows and eventually stops, leaving only the carotene molecules and a yellow-orange color. During the fall, anthocyanins form, giving the purplish-reddish hues to the leaves.
Try out the following experiment to see the hidden colors in a green leaf and predict what color the tree’s leaves will turn in the fall. If you’re a member of our Kids Club, be sure to grab your favorite adult to help you with the experiment.
You will need:
Green leaves from different trees in your yard or neighborhood
Glass cups, jars or beakers
Step one: Sort the leaves you’ve collected by the type of tree they came from so you can compare results. You’ll need one glass for each type of leaf.
Step two: Tear the leaves into several pieces and place them in your glass, then add enough rubbing alcohol to cover the pieces. Cover the glass with plastic wrap so the alcohol does not evaporate.
Step three: Carefully place the glass in a dish of hot water for 30 minutes, until the alcohol turns green. The alcohol is absorbing the pigments from the leaves.
Step four: Cut a half-inch wide strip of the coffee filter for each glass and tape each to a pencil. Balance each pencil across a glass so the filter is suspended into the glass. Let the strip just barely touch the alcohol and pigment mixture.
Step five: The alcohol will slowly travel up the filter. After 30–90 minutes your filter should begin to show several different colors as the different pigments begin to separate. You may see different shades of green along with several other colors.
Step six: Record your results! Which leaves had the most colorful pigments? Based on your observations, can you predict which trees will have vibrant colors in the fall?
If you’d like to save your results and continue making observations in the fall, you can keep a nature journal. Bring your notes along with you to Members’ Night!