Plant World

Plant Structure and Function

Why do tree leaves change color in the fall?

The carotenoids (pigments in the photosynthesizing cells), which are responsible for the fall colors, are present in the leaves during the growing season. However, the colors are eclipsed by the green chlorophyll. Toward the end of summer, when the chlorophyll production ceases due to declining daylight and a decrease in temperature, the other colors of the carotenoids (such as yellow, orange, red, or purple) become visible. Listed below are the autumn leaf colors of some common trees.

Tree Color
Sugar maple, sumac Flame red and orange
Red maple, dogwood, sassafras, scarlet oak Dark red
Poplar, birch, tulip tree, willow Yellow
Ash Plum purple
Oak, beech, larch, elm, hickory, sycamore Tan or brown
Locust Stays green until leaves drop
Black walnut, butternut Drops leaves before they turn color


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