Iridescence in shade-dwelling plant species linked with photosynthesis

Popular Mechanics : Certain plant species, such as the Malaysian tropical Begonia pavonina, are unusual because of the iridescent blue of their leaves. Heather Whitney of the UK’s University of Bristol and her colleagues recently investigated why the leaves are blue. Using an electron microscope, the researchers were able to study the cellular structure of the plant’s leaves; they found that unlike most plants, the Begonia‘s chloroplasts have a very rigid, precise arrangement. The ordered structure not only acts like a dense crystal that favors red–green light and reflects blue light, but it also causes light to slow down as it passes through. As a result the Begonia plant, which dwells in shadowy conditions on the rainforest floor, is 10% more efficient at photosynthesis than it otherwise would be, the researchers say. Furthermore, the plant also contains some normal chloroplasts. The mix of the normal and highly ordered chloroplasts may allow the plants to adjust between normal light levels and extremely low levels.