Chlorophyll does not reflect green light – how to correct a misconception

ABSTRACT

Plant leaves are green because they contain the green photosynthetic pigments, chlorophylls a and b. Popular science literature, and sometimes even textbooks, state that the greenness is caused by reflection of green light by chlorophyll. In the present study, we compared the reflectance spectra of green leaves to yellow or white leaves of the same species. Chlorophyll-deficient leaves reflected green light more efficiently than green leaves of the same species, which conclusively refutes the misconception. The data show that the green colour of leaves is caused by preferential absorption of blue and red light by chlorophyll, not by reflection of green light by chlorophyll. The data suggest that the cellulose of the cell walls is the main component that diffusely reflects visible light within plant leaves.

KEYWORDS:

• Chlorophyll
• reflectance
• green
• green leaves
• visible light
• absorbance

Acknowledgments

Ms. Eija Leino is warmly thanked for Poinsettia leaves used for data validation. The authors thank the Quora social network service and Wikipedia for inspiration.

Disclosure statement

No potential conflicts of interest were reported by any of the authors.

Supplementary material

Supplemental data for this article can be accessed here.

Additional information

Funding

This study was financially supported by the Academy of Finland [grants 307335 and 333421] and University of Turku Graduate School (UTUGS).