Most leaves appear green because they contain a pigment called chlorophyll. Chlorophyll absorbs light most efficiently in the red and blue parts of the light spectrum but reflects green light. This reflected green light is what reaches our eyes, making the leaves look green.
Role of Chlorophyll
- Chlorophyll is essential for photosynthesis, the process by which plants convert sunlight into chemical energy (glucose) for growth and survival.
- There are two main types of chlorophyll: chlorophyll-a (blue-green) and chlorophyll-b (yellow-green), which contribute to variations in the shades of green in leaves.
- The high concentration of chlorophyll in leaf cells means more green light is reflected, so green is the dominant leaf color.
Absorption and Reflection of Light
- Leaves absorb around 90% of red and blue light and about 70-80% of green light, but the green light is reflected more efficiently, which is why leaves appear green to human eyes.
- Humans are more sensitive to green light, enhancing the perception of leaf greenness.
Biological Purpose
- The green light is least utilized for photosynthesis compared to red and blue light, which is why it is mostly reflected rather than absorbed.
- Reflecting green light might also help protect the photosynthetic machinery from excess light damage.
In summary, leaves appear green due to the reflection of green light by chlorophyll molecules that absorb other wavelengths for photosynthesis, making green the dominant color perceived.
