Blue Leaf Special

FLICKR, CLIVIDThe blue leaves of shade-dwelling Begonia capture extra light compared with typical leaves, enhancing the plants’ photosynthetic capabilities, scientists from the University of Bristol, U.K., reported in Nature Plants this week (October 24). Begonia epidermal chloroplasts—or iridoplasts—contain “a photonic crystal structure formed from a periodic arrangement of the light-absorbing thylakoid tissue itself,” the authors reported.

Examining magnified B. pavonina cells, study coauthor Heather Whitney, who studies plant iridescence at Bristol, observed iridoplasts arranged in such a way that “the light that is passing through gets slightly bent—it’s called interference,” she told The Washington Post. “So you have this sort of iridescent shimmer.”

In their paper, the authors proposed a reexamination of chloroplast function. “Chloroplasts are generally thought of as purely photochemical; we suggest that one should also think of them as a photonic structure with a complex interplay between control of light propagation, light capture and photochemistry.”