Plants have tiny little organelles in their cells called chloroplasts. Chloroplasts are where photosynthesis happens, so they contain an important pigment called chlorophyll. Chlorophyll is green. (See yesterday’s post for an explanation). But chloroplasts can only use some of the light from the Sun.
To use other colors (other wavelengths) of light, plants have other pigments that capture other colors. They also reflect different colors than chlorophyll, so they appear to be different colors. Carotenoids, for example, appear yellow to orange. These pigments are in the leaves all year long, but there isn’t very much of them. There’s a LOT more chlorophyll, so it covers up the other pigments and we see the plants as being green.
In the fall, when the leaves start to die, they lose their chlorophyll. The other pigments are now visible, with all of the splendid colors of autumn.
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