Another Way to Look at Autumn Leaves

For the most part, the beautiful colors of fall leaves are there all the time, except you can't see them because of the abundance of green chlorophyll. Even if you live somewhere that doesn't get cold, the shorter days of autumn cause less chlorophyll to be produced in plant leaves, so you'll start to see the leaves change color. You can see this just by looking at the trees, but another way to examine the change in pigment concentrations is to perform paper chromatography on the leaves. This is easy and doesn't require any unusual chemicals or equipment.

Leaf Chromatography Materials 2-3 large leaves (or several small leaves) rubbing alcohol (isopropyl alcohol, 70-95%) coffee filters or filter paper Finely tear or chop the leaves. I like to put them in a coffee grinder for a few seconds. Alternatively, you could add a very small amount of alcohol to the leaves and run them through a blender. If you haven't already, add just enough alcohol to cover the chopped leaves. Allow time for the pigment to leach into the alcohol. Setting the container of leaves and alcohol into a bowl of hot water may speed the process. Allow about half an hour for the alcohol to pick up the color from the leaves. Make a Leaf Chromatogram Tear or cut a strip of coffee filter. Place one end of the strip in the leaf and alcohol mixture. The alcohol will run up the paper. As it evaporates, the pigment will be pulled up the strip. Smaller pigment molecules will move further/faster up the strip. Larger pigment molecules will stay closer to the starting point of the chromatogram. Allow the chromatogram to develop until you are pleased with the separation.If you collect leaves from the same plant as the season progresses, you'll be able to track the change in the pigment composition of the leaves. A similar process occurs in the spring or in other situations in which the environmental conditions change.

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