There are three major components for pigment change in leaves.
Plastids (1) are minute leaf structures that carry green chlorophyll and color the summer forest. Carotenoids (2), stored in plastids, and anthocyanins (3) in sap are the leaf paints (pigments) that color the forest of autumn.
Plastids (1) are minute leaf structures that carry green chlorophyll and color the summer forest. Carotenoids (2), stored in plastids, and anthocyanins (3) in sap are the leaf paints (pigments) that color the forest of autumn.
Green plastids (figure 1): A green leaf is green because of the
presence of a group of pigments known as chlorophylls. Minute
structures called plastids contain the chlorophyll within the leaf.
When these green pigments are abundant in the leaf's cells, as they are
during the growing season, the chlorophylls' green color dominates and
masks out the colors of any other pigments that may be present in the
leaf. Thus the leaves of summer are characteristically green.
Carotenoid pigments (figure 2): These pigments are also found in plastids. The carotenoids occur, along with the chlorophyll pigments, in tiny structures - called plastids - within the cells of leaves. Sometimes they are in such abundance in the leaf that they give a plant a yellow-green color, even during the summer. But usually we become aware of their presence for the first time in autumn, when the leaves begin to lose their chlorophyll.
Carotenoid yellow and orange color is in many living things, giving characteristic color to carrots, corn, canaries, and daffodils, as well as egg yolks, rutabagas, buttercups, and bananas. Their brilliant yellows and oranges tint the leaves of such hardwood species as hickories, ash, maple, yellow-poplar, aspen, birch, black cherry, sycamore, cottonwood, sassafras, and alder.
Anthocyanin pigments (figure 3): These pigments occur in the sap of cells. The anthocyanins temporarily color the edges of some of the very young leaves as they unfold from the buds in early spring. They also give the familiar red and purple color to such common fruits as cranberries, red apples, blueberries, cherries, strawberries, and plums.
In an autumn forest they show up vividly in the maples, oaks, sourwood, sweetgum, dogwood, tupelo, black gum, and persimmon. These same pigments often combine with the carotenoids' colors to give us the deeper orange, fiery reds, and bronzes typical of many hardwood species.
(Information for this page found at About.com)