If you live in the majority of the U.S., fall means leaves on the trees will change color, which means your kid will ask you, “Why are the leaves changing color?” You can make up something awesome, like “All the trees just got into punk music and discovered Manic Panic hair dye,” or you could go with the real answer. If you’re interested in being all right and stuff, the U.S. Forest Service’s Vermont foliage expert, Dr. Paul Schaberg, has your back.
YOUR KID’S QUESTIONS
Why are leaves green?
The green chemical is sort of wimpy and can’t handle the cold. When it goes away, you can see the yellow chemical.Leaves have a special chemical in them that turns sunlight into food that the tree eats, and that chemical is green.
Why do leaves turn yellow?
Leaves have another special chemical that’s a lot like the green one, but it’s yellow. It’s actually there all year long, but you can’t see it until the Fall. That’s when the days get shorter and the air gets colder, which makes the green chemical go away, because the green chemical is sort of wimpy and can’t handle the cold. When it goes away, you can see the yellow chemical.
So … why do leaves turn red, then?
The red comes from a third chemical. Once the days get really short and the air gets really cold, the red covers up the yellow in the same way that the green covers it up the rest of the year. But the red doesn’t turn sunlight into food. It’s actually a bit of a mystery what it does, but we think the red keeps the leaves on the tree a little longer. That lets the tree suck up all the food that’s in each leaf before it falls off, which ensures the tree has enough to eat all winter long.
But, how come some leaves don’t turn any color and don’t even fall off the tree in the winter?
All tree leaves turn sunlight into food, but some kinds do it differently than others. The ones that change color make lots of food in the spring and summer, so the tree can store it up and eat it all fall and winter. The ones that don’t change color make a lot less food, but keep making it during the fall and winter. It’s a little like the old story of the tortoise and the hare – different ways to get to the same place.
Any suggestions for showing my kid how the color changing process works?
Find a tree where the leaves on the outside of the crown are already yellow, and look at the leaves situated directly below the outer layer of the crown. If you can find ones that are only partially exposed to sunlight, the exposed part of the leaf will often be yellow like the outer leaves and a distinct line will separate that from the shaded part that remains a green.