The Blue Ridge Parkway is one of the most famous drives in the US. Last fall, I had the good fortune of driving through it at the perfect time. It was undoubtedly the most beautiful ride of my life. I had no destination and I never wanted the drive to end. Surrounded by a wonderland of yellow and orange leaves, it felt like I was driving through a garden, not on a public road. The sight of all that fall foliage was simply breathtaking.
When autumn arrives, life suddenly becomes more enjoyable. When you see all those beautiful yellow and orange leaves on the road, all your worries about traffic and work stress just vanish. People around you seem happier, eager to soak up the natural beauty of the world around them.
However, have you ever wondered how all those leaves magically change their green color to yellow, orange and red when autumn finally arrives?
How Do Leaves Get Their Color?
During summer vacations, when you are playing outside, the trees are working hard to provide you with oxygen for all of your activities. Then, when you get tired and are sweating from the summer sun, these trees provide you with shade beneath their green leaves.
Trees take water from the ground through their roots and carbon dioxide from the air. They use sunlight to turn water and carbon dioxide into oxygen and glucose. Glucose is a type of sugar that trees use as food. This process is known as photosynthesis, and a vital chemical called chlorophyll helps in photosynthesis.
Chlorophyll is a green color pigment that is abundantly found in leaves; therefore, it is chlorophyll that gives leaves their green color.
Why Do Leaves Change Their Colors?
Yellow and Orange
Other than chlorophyll, leaves contain two other pigments: carotene (orange color) and xanthophyll (yellow color).
During the summer, chlorophyll is the busiest pigment, as it is required for photosynthesis. The abundance of chlorophyll masks the orange and yellow color pigment that lie beneath.
Trees work hard in the summer season to produce food, which they can store for the autumn and winter season. Autumn is the time for the trees to finally take a rest after all that hard summer work.
In some parts of the world, during autumn and winter, days become shorter and nights become longer. Therefore, the amount of sunlight decreases significantly, and as a result, plants are not able to perform photosynthesis. As the amount of sunlight reduces, the amount of chlorophyll also reduces and becomes less dominant. Due to this, the carotene (orange) and xanthophyll (yellow) pigments that were already present in the leaves begin to show.
Leaves look even more beautiful when they are red in color. This red color is the result of the anthocyanin (red color) pigment. Anthocyanins, unlike carotene and xanthophyll, are not present in leaves all the time. The tree synthesizes anthocyanins only after the chlorophyll content reduces significantly. Anthocyanins are produced as a form of protection for the leaves; they allow the tree to recover nutrients in the leaves before they fall off.
In short, leaves do not actually change their color. They simply lose their green color during the autumn.
We should be very thankful for trees , as they let us enjoy the beauty of nature in every season. Autumn is like a second spring, when every leaf is a flower.
- Why Leaves Change Color – Environmental Science and Forestry
- Science of Fall Colors – US Forest Service