Why is grass green?

Look across a field, a lawn, or a meadow, and the color you see is green. Grass, leaves, and most plants share this same color, so much so that green has become the color we associate with nature itself. But why green, and not red, blue, or purple? The answer connects the biology of plants with the science of light and color, and it all comes down to a remarkable substance inside the grass.

To understand the color of grass, we first need to understand how color works. Sunlight looks white, but it is actually a mixture of all the colors of the rainbow. When light strikes an object, the object absorbs some of those colors and reflects others. The colors that bounce back to our eyes are the colors we see. A grass blade looks green because, out of all the colors in sunlight, it is mainly green light that gets reflected back to us.

The reason grass reflects green light is a pigment it contains called chlorophyll. A pigment is simply a substance that gives something its color by absorbing certain colors of light. Chlorophyll is packed inside tiny structures within the cells of grass blades. It is very good at absorbing red light and blue light from sunlight, but it does not absorb green light well. That unabsorbed green light is reflected away, travels to our eyes, and so the grass appears green.

Chlorophyll is not in grass simply to make it look nice. Its real job is far more important: it powers photosynthesis, the process by which plants make their own food. Chlorophyll captures the energy from the red and blue light it absorbs, and the plant uses that energy to turn water and carbon dioxide into sugars for growth. So the green color of grass is really a side effect of this life-giving process. The green we see is the light the plant did not need, while the energy it kept keeps it alive.

This article was written using information from Wikipedia.