Why is grass green?
Grass is green because it contains chlorophyll, a pigment that absorbs red and blue light for photosynthesis but reflects green light, which is what we see.
Chlorophyll is found inside tiny structures called chloroplasts in plant cells. It captures energy from sunlight, which plants use to turn carbon dioxide and water into sugar and oxygen. This process, called photosynthesis, feeds the plant and produces much of the oxygen we breathe.
Sunlight contains all colors of visible light. Chlorophyll absorbs mostly red and blue wavelengths, which carry the energy plants need. It absorbs much less green light, so green is reflected and scattered back to our eyes, giving grass and leaves their color.
Other colors in plants
Plants also contain other pigments, such as yellow and orange carotenoids. In autumn, many trees stop making chlorophyll, so these hidden colors become visible, and some leaves produce red pigments called anthocyanins. When grass dries out or lacks light, it can turn yellow or brown as chlorophyll breaks down.
Did You Know?
Scientists are still studying why plants evolved to reflect green light, which carries a lot of energy. One idea is that it protects them from absorbing too much energy too quickly.