We all enjoy the colors of the leaves in fall. The changing foliage of this season never ceases to amaze and delight us, but have you ever wondered how and why an autumn leaf changes color ? Why do leaves, like maple, turn bright red? Where do the yellow and orange tones come from?
To answer these questions, the first thing we have to understand is what leaves are and what they do.
We know photosynthesis
We could say that leaves are nature’s food factories. Plants take in water from the soil through their roots and take a gas called carbon dioxide from the air. Plants use sunlight to convert water and carbon dioxide into oxygen and glucose. Oxygen is a gas in the air that we need to breathe and glucose is a type of sugar. Plants use glucose as food for energy and as a fundamental pillar for their growth.
The way that plants convert water and carbon dioxide into oxygen and sugar is called photosynthesis, which means “growing with light.” A chemical called chlorophyll helps photosynthesis occur, and it is what gives plants their characteristic green color.
Plants in autumn prepare for winter
The plants are busy growing all summer and into fall, but deep down they know that the dark, dry days of winter are coming. As the days grow shorter, the trees use this signal to know that it ‘s time to start preparing for the harsh winter .
During the cold season there is not enough light or water for photosynthesis, which makes many trees rest and live on the food they stored during the summer in these months. The plants consequently begin to shut down their food-generating factories and the green chlorophyll disappears from the leaves. And as the bright green fades we begin to see yellow and orange colors, although the truth is that in small quantities these colors have been in the leaves all the time , we just couldn’t see it due to the strong action of chlorophyll, that hides them.
The bright red and purple hues that we also see in the leaves are mostly produced in the fall. In some trees, glucose remains trapped in the leaves even after photosynthesis stops . Sunlight and cool autumn nights make the leaves turn this glucose into an absolutely gorgeous red color. Other shades, such as the brown color of trees like oaks, are made from debris left on the leaves.
In short, the beautiful shades of the leaves in autumn are due to a combination of all these things, causing the beautiful colors of the fall foliage that luckily we can enjoy each year.
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