Plants are green because they contain a pigment called chlorophyll, which absorbs light most efficiently in the blue and red parts of the spectrum but reflects green light, making the plants appear green to our eyes. This selective absorption happens because red light is most useful for photosynthesis, the process by which plants convert light energy into chemical energy. The green light is reflected rather than absorbed, so plants look green.
Chlorophyll's role in photosynthesis explains the green color: plants absorb light to produce sugars and energy, but chlorophyll reflects green light, which is why it does not get used as much as red or blue light. While black leaves might absorb all light theoretically, green leaves maximize efficient light distribution internally because of the limitations of enzymes like Rubisco and the need to balance light absorption and usability.
Additionally, scientific understanding suggests that evolution has selected green as the optimal color for plants under sunlight conditions on Earth, balancing energy absorption and protection from fluctuating light intensity.
Thus, plants are green mainly because chlorophyll absorbs other colors more effectively and reflects green, which is the unabsorbed light that we see.
