Why leaves change colour
Learn why some leaves change colour in autumn through a short, simple explanation.
In autumn, some trees change from green to yellow, orange or red. The change can happen slowly, so one tree may have several colours at the same time. Not every kind of tree loses its leaves for winter.
Kew, the Royal Botanic Gardens, explains the role of chlorophyll. This is a green substance in leaves. It helps a plant use sunlight to make food. During summer, the plant replaces chlorophyll as it breaks down, and green is the strongest colour we see.
In trees that lose their leaves for winter, this process slows in autumn. As the green becomes less strong, other colours become easier to see. Different kinds of trees contain different mixtures of substances, so their autumn colours are not all the same.
The process also depends on conditions such as day length and temperature. A cold night does not simply paint every leaf red. When you look at a tree, you may see leaves at different stages of change. Some may still be green while others are ready to fall.
Words to take with you
- substance
- A particular kind of material.The green substance is inside the leaf.
- replace
- To put something new in place of something old.We need to replace the broken cup.
- mixture
- Different things together.The bag contains a mixture of seeds.
- temperature
- How hot or cold something is.The temperature is lower at night.
- stage
- One part of a process.The plant is at an early stage of growth.
Check your understanding
Choose an answer, then check each question.
Use your English
Explain the colour change in two simple steps using the words chlorophyll and autumn.
Say your answer aloud or write two or three sentences.