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Plants dispersed by the wind have developed ingenious ways of raising their seeds. The common dandelion (Taraxacum officinale) uses a bristle pack that strengthens drag resistance and helps keep seeds in the air. A new study, led by researchers Ignazio Maria Viola and Naomi Nakayama of the University of Edinburgh, shows that the movement of air around and inside the dandelion parachute beam allows seeds to long distances.
The common dandelion (Taraxacum officinale). Image credit: Petra D.
"We conducted experiments to better understand why dandelion seeds were flying so well, while their parachute structure was largely empty spaces," said Dr. Viola, Dr. Nakayama and their colleagues.
"Our study revealed that a ring-shaped air bubble forms when air passes through the hair, reinforcing the resistance that slows down the descent of each seed to the ground."
This form of air bubble – called the separate vortex ring – is physically detached from the bristles and is stabilized by the air passing through it.
The amount of air flowing through, which is essential to keep the bubble stable and directly above the seed in flight, is precisely controlled by the spacing of the bristles.
This mechanism of flight of the bristled parachute underlies the regular flight of the seeds.
It is four times more efficient than is possible with conventional parachute design.
"The porous dandelion parachute could inspire the development of small drones requiring little or no power consumption," said the study's authors.
"Such drones could be useful for remote sensing or monitoring air pollution."
"Taking a closer look at nature's ingenious structures – such as the dandelion parachute – can reveal new perspectives," said the study's first author, Dr. Cathal Cummins, also of the University of Toronto. # 39; Edinburgh.
"We have found a natural solution for flight that minimizes hardware and energy costs, which can be applied to sustainable technology engineering."
The results appear in the October 18, 2018 issue. Nature.
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Cathal Cummins et al. 2018. A separate vortex ring underlies the theft of the dandelion. Nature 562: 414-418; doi: 10.1038 / s41586-018-0604-2
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