During the spring and summer the leaves have served as factories
where most of the foods necessary for the tree’s growth are
manufactured. This food-making process takes place in the leaf
in numerous cells containing chlorophyll, which gives the leaf
its green color. This extraordinary chemical absorbs from
sunlight the energy that is used in transforming carbon dioxide
and water to carbohydrates, such as sugars and starch. Along
with the green pigment are yellow to orange pigments, carotenes
and xanthophyll pigments which, for example, give the orange
color to a carrot. 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 foodmaking 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 thr