Leaves on deciduous trees change color in autumn from green to various hues of lime, yellow, gold, orange, red and brown because of a combination of shorter days and colder temperatures.
Throughout spring and summer, green chlorophyll (which allows trees to absorb sunlight and produce nutrients) is made and replaced constantly. However, as days grow shorter, “cells near the juncture of the leaf and stem divide rapidly but do not expand,” reports Accuweather.com, “This action of the cells form a layer called the abscission layer. The abscission layer then blocks the transportation of materials from the leaf to the branch and from the roots to the leaves. As Chlorophyll is blocked from the leaves, it disappears completely from them.”
That’s when vivid yellow xanthophylls, orange carotenoids and red and purple anthocyanins emerge.
Read full story at Why Do Leaves Change Color? – California Fall Color
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