Gregory Moore does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
This is an article from Curious Kids , a series for children. All questions are welcome — serious, weird or wacky! Without photosynthesis there would be no plants or people on Earth. Dinosaurs would not have been able to breathe and the air and oceans would be very different from those we have today. So the green chemical chlorophyll is really important. Weather is also an important part of the color change. In the fall, the temperatures get colder and there is also more rain and snow.
Changes in these weather conditions can play a role in how early the leaves change and how long they keep their beautiful colors. Extreme weather changes can also have an effect on the leaves. So if you want to know how long the colors will last this fall, be sure to keep an eye on the weather! The delayed greening has been studied as an adaptive strategy for the plant.
One line of thought is that the young leaves are not yet performing photosynthesis, so they are not capturing energy from the sun and making food, therefore they are without much nutritive value to the plant.
There also is little nutritive value to an herbivore. The plant is investing energy to grow the new leaf, so avoidance of herbivory allows the investment a better chance to mature. If being red decreases the risk that the new growth will be eaten by herbivorous animals, then the plant has used a successful strategy.
Most of the year these colors are masked by great amounts of green coloring. But in the fall, because of changes in the length of daylight and changes in temperature, the leaves stop their food-making process. The chlorophyll breaks down, the green color disappears, and the yellow to orange colors become visible and give the leaves part of their fall splendor. At the same time other chemical changes may occur, which form additional colors through the development of red anthocyanin pigments.
Some mixtures give rise to the reddish and purplish fall colors of trees such as dogwoods and sumacs, while others give the sugar maple its brilliant orange. The autumn foliage of some trees show only yellow colors.
Others, like many oaks, display mostly browns. All these colors are due to the mixing of varying amounts of the chlorophyll residue and other pigments in the leaf during the fall season. As the fall colors appear, other changes are taking place.
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