Why Do Leaves Change Color In The Fall? - By Felicia
In many places around the planet, autumn is marked by the gradual, magnificent shift of green foliage to vibrant reds, oranges, yellows, and purples. Green leaves have a green appearance due to the existence of a pigment called "chlorophyll", which is indispensable in photosynthesis. In temperate regions, crisper winters pose a risk to the leaves of broad leaf trees and other perennials, and so these plants drop their leaves in a controlled fashion to reduce injuries and conserve energy. This event is usually triggered by the declining day length and plunging temperatures in autumn. Leaf abscission (the technical term for the dropping of leaves) begins with the deterioration of chlorophyll. As the green fades away, yellow and orange pigments known as carotenoids are displayed in the leaves of many species. In other plants, pigments called anthocyanins accumulate in the leaves at this point, giving them shades of red and purple. Some of the most alluring fall foliage features both types of pigments, often with one hue giving way to the next as the season progresses. Eventually, every single leaf falls, and the plant goes dormant for the lengthy winter months.
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