October 2024 Kids’ Corner
Deep Dive into fall foliage!
In this Kids Corner you’ll:
- Learn about the three types of pigment molecules that give leaves their unique fall colors.
- Practice mixing pigments to match fall foliage colors
Fall is a beautiful time in the forests of New Hampshire! Deciduous trees (trees that lose their leaves in the winter) put on a show of beautiful color before their leaves fall to the ground. People visit from all over the world to see the mountains painted in red, orange, yellow, and green. But what’s going on inside the leaves to create those colors?
Plants make their own food (a sugar called glucose) in a process called photosynthesis. The energy for this process comes from the sun. Tiny molecules called pigments found in plants’ leaves absorb the energy in sunlight to power photosynthesis. There are three main types of pigments that trees use for photosynthesis: chlorophyll, carotenoids, and anthocyanins. You can think of them as green, yellow, and red pigments.
The main pigment that most of our trees use for photosynthesis is chlorophyll. Since trees have so much chlorophyll in their leaves, and since chlorophyll is green, the leaves of most deciduous trees look green during the spring and summer.
Fun Fact: Chlorophyll is green because it reflects green back to our eyes. This means that green is actually the least useful color of light for photosynthesizing green leaves!
Deciduous trees can’t photosynthesize in the winter without leaves, so as winter approaches the trees start to break down the chlorophyll in their leaves. When a leaf loses its chlorophyll, we can see its other pigments, like carotenoids.
Carotenoids are another pigment used in photosynthesis, but instead of green, carotenoids in leaves are yellow. Yellow fall leaves are colorful because the carotenoids are no longer covered up by the green chlorophyll!
Fun Fact: Carotenoids also give fruits and vegetables their bright orange, red, and yellow colors. They are antioxidants (chemicals that protect your body’s cells from damage), which are very healthy for you. Eating a variety of colorful foods is a good way to get lots of antioxidants!
Red fall leaves are caused by a third pigment called anthocyanins. Unlike carotenoids, anthocyanins are actually produced by the tree in the fall just before the leaves fall off. The redness of a leaf in the fall depends on how much anthocyanin that tree (or even each individual leaf) produces! Not all trees produce anthocyanins, so not all trees have red leaves in the fall.
Fun Fact: Scientists think anthocyanins might act as a type of sunscreen for leaves in the fall while they break down their chlorophyll. The idea is that the anthocyanins absorb the sun’s energy to protect the chlorophyll while the plant takes the chlorophyll apart to use its nitrogen!
Leaves can contain some or all of these pigments in different combinations, creating endless fall color possibilities, even on the same tree! Now that you know about pigments, let’s practice! What do you notice about the pigments in each of these leaves?
The orange in these leaves comes from a mix of anthocyanins and carotenoids.
This tree has broken down its chlorophyll and we can see the yellow color of the carotenoid pigments
These leaves are deep red because they have produced anthocyanins
These leaves have a mix of chlorophyll and carotenoids
This brownish color comes from a mix of chlorophyll and anthocyanins
Your Turn!
You’ll need:
- Red, Yellow, and Green paint (optional: brown since leaves also have brown tannins in them)
- Paper and paint brush
- Fall leaves
With your grown up, go outside and collect a few of the most colorful leaves you can find. Then, one at a time, try mixing your paint colors to match your leaves. When you have the closest match you can get, describe which photosynthetic pigments, and in what amounts you are seeing in your leaves.
Sources:
Thanks to our partner, the Gale River Cooperative Preschool in Bethlehem, for helping our area parents get kiddos outside for fun no matter the time of year.
