Peacock Begonia's Mysterious Iridescent Blue Hue Lets It Thrive in the Dark

New research reveals that the plant's shimmering blue leaves allow it to survive in the dim rainforest floors of southeast Asia.

Most of us know that plants are green thanks to chlorophyll, the photosynthetic pigments that turn sunlight into energy. That's magic enough right there, but for plants challenged in the sunlight department, what to do?

Since plants can't just get up and walk over to an environment that might better suit them, they adapt. And evolving to meet the specific demands of a habitat has led to a mind-boggling array of strange and wonderful organisms. Not the least of which is the beguiling Begonia pavonina, or peacock begonia – a plant whose iridescent blue leaves have been a mystery. Until now, at least, since new research from the University of Bristol has shed some light on the subject.

B. pavonina dwells in the dim rainforest floors of southeast Asia and has adapted to the meager sunlight by basically becoming blue. In addition to the verdant green chlorophyll, the peacock begonia contains photosynthetic structures called iridoplasts, says co-author Heather Whitney, an expert in plant surface interactions at the University.

Sarah Kaplan from The Washington Post reports:

Whitney and her colleagues examined B. pavonina cells under a microscope, they noticed that the iridoplasts had a very strange shape. They were layered on top of one another, membrane upon membrane separated by a thin film of liquid, almost like a stack of pancakes held together with maple syrup. The effect is similar to what happens when you see oil on top of water in a puddle.

“The light that is passing through gets slightly bent – it's called interference,” Whitney says. “So you have this sort of iridescent shimmer.”

© University of Bristol

These layers of iridoplasts work to amplify the light by bending it repeatedly, creating a dramatic shimmer. This allows the structures to take in all the types of light available in the dark landscape beneath the forest canopy, writes Kaplan, long wavelengths like red and green. The blue light gets reflected back, much to the delight of those of us who are partial to shimmering blue plants. For Whitney, the discovery adds to the catalog of plants' incredible versatility.

“Plants aren't just factories," Whitney says, and can adjust over time as need be. The iridoplasts of B. pavonina provide a beautiful example of actually changing their structure to manipulate light.

“And who knows?” she adds. “They’ve probably got loads of tricks we don’t know about yet, because that's how they survive.”

Via The Washington Post