Answer card
Why do leaves change colour in autumn?
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What we know
- True: Leaf cells contain “chlorophyll, which gives the leaf its green color”. It is what lets the leaf make food from sunlight. SUNY College of Environmental Science and Forestry — Why Leaves Change Color
- True: “Along with the green pigment are yellow to orange pigments … Most of the year these colors are masked by great amounts of green coloring.” SUNY College of Environmental Science and Forestry — Why Leaves Change Color
- True: “But in the fall, because of changes in the length of daylight and changes in temperature, the leaves stop their food-making process.” As the green breaks down, the yellow and orange that were there all along show through. SUNY College of Environmental Science and Forestry — Why Leaves Change Color
- True: Reds are different: “other chemical changes may occur, which form additional colors through the development of red anthocyanin pigments.” SUNY College of Environmental Science and Forestry — Why Leaves Change Color
What we made simpler
We left out the names of the yellow pigments (carotenes and xanthophylls) and how the tree pulls food back out of its leaves before they fall.
Still open
Why some trees bother to make new red pigment just before their leaves drop is still argued about.
Next why
Why do some trees keep their leaves all winter?
GrowForge — Plant Adaptations and Evolution →Try it
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