How do plants survive extreme desert conditions with very little available water? Long roots that can reach deep water reserves, right?
Not this gravity-defying plant.
Syntrichia caninervis (aka seriously awesome desert moss) uses tiny hair-like structures on the tips of its leaves to absorb water from the atmosphere until droplets form and flow, rather quickly, to the leaf. And sometimes it does it upside-down, like this:
“The forces that propel the droplet toward the leaf structure are so strong that the droplet can flow upward against gravity just as fast as if it’s going downward,” said BYU Chemical Engineering professor William Pitt, coauthor of a new study on the plant. “It can collect water from any direction.”
This fascinating survival behavior is made possible by nano-sized grooves on the leaf hairs, or awns, that trap microscopic levels of water from fog or even humid air. Each hair features barbs where the collected water forms small droplets that zip along the hair to the leaf.
“They zip so fast that sometimes we can’t see them disappear,” Pitt said.
Details of this highly-evolved desert-surviving plant were published Monday in Nature Plants in a paper coauthored by researchers at Brigham Young University, Utah State University and the Chinese Academy of Sciences.
The research started in China, where researchers at the Xinjiang Institute of Ecology and Geography noticed that if they clipped off the leaf hairs the moss didn’t grow as well. The Chinese collaborators (Professor Yuanming Zhang, Nan Wu and Ye Tao) started working with professors and a student at BYU and Utah State University to figure out what was going on the microscopic and nanoscopic level.
BYU grad student and lead study author Zhao Pan discovered how the hairs collected water after setting up a fog chamber and photographing the hairs encountering moisture. Utah State mechanical engineering professor Tadd Truscott used high-speed video and and an electron microscope to gather more visual data of the plant in action.
“There are several exciting angles to this research,” Truscott said. “For example, there are processes in industry where we need to extract moisture from a humid environment. It might be possible to create a man-made version of the nano- and micro-scale grooves we see in the moss awn and use that in a manufacturing environment.”
“We call it bio-inspired engineering,” added Pitt. “We look at how our natural world works and say, hey, let’s take that principle and apply it to something that we use in our life.”