“In that kind of situation, [this model] could be incredibly relevant.”. Seeds from plants like dandelions, swan plants and cottonwood trees are light and have feathery bristles and can be carried long distances by the wind. A fair compromise, the researchers found, is for the seeds to hit a sweet spot around 100 bristles per pappus. Taking a theoretical approach, a team led by fluid dynamicist François Gallaire of the Swiss Federal Institute of Technology Lausanne devised a mathematical model of the super-steady nature of dandelion vortex rings. ScienceDaily, 20 November 2017. Financial support for ScienceDaily comes from advertisements and referral programs, where indicated. Each dandelion seed head can contain dozen of these many single-seeded achenes. Additional funding is provided by the NOVA Science Trust. “If we were on a different planet...we might need to come up with different ways of dealing with drag,” Braybrook says. Compared to a solid, parachute-shaped structure of about the same size, the pappus is actually four times as efficient at creating drag, the force that counteracts gravity to keep the seed airborne, the researchers found. ScienceDaily. Investigators reveal why, at low Reynolds numbers, the rules for big parachutes don't apply to small dandelions. There’s some wiggle room, but at lower numbers, the seed would have trouble staying afloat; too much higher, and things might start to get shaky. The fewer filaments atop a seed, the higher its porosity, and thus stability—good news for a skyfaring seed. In the wake of their golden days of flowering, the tops of dandelion plants mature into dozens of flight-ready seeds, each tethered to its own personal parachute. But even when our lungs are the source of the initial gust, we humans can’t take all the credit for dandelion fight. The Secret Life of Scientists and Engineers. Or view hourly updated newsfeeds in your RSS reader: Keep up to date with the latest news from ScienceDaily via social networks: Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Major funding for NOVA is provided by the David H. Koch Fund for Science, the Corporation for Public Broadcasting, and PBS viewers. “Nature has optimized something so beautiful,” Braybrook says. This fast-moving funnel was so good at recycling air that it generated an ever-present pocket of low pressure just above the seed, sucking it upward into an easy, breezy cruise—and delaying its inevitable descent. The wind-aided seed dispersal allows dandelions to grow rapidly and abundantly far and wide. But because the pappus is porous, some air flows through it instead, streaming between the bristles of the seed’s thin toupee. (2017, November 20). With two recent studies, the physics behind dandelion seed dispersal is now taking flight. Mainly caused by updrafts, in the simulations more than 0.05 % of dandelion seeds were dispersed beyond 100 m, a distance commonly used to define LDD. At some point or another, most of us have played travel agent to a dandelion. But the theoretical model does more than add credence the first paper’s experimentally-driven results, Seale says. American Physical Society's Division of Fluid Dynamics. We humans (and most of the things we buy) are far too big and bulky for the same physical principles to apply. The work can potentially be applied to miniaturizing MAVs useful for remote observation and dispersion in a range of applications, from agriculture to space exploration, especially in conditions hazardous to humans. In the laboratory, researchers showed that building a low-porosity miniature parachute leads to a destabilizing of this STV, and hence a turning moment causing the fruit to spin. One thing that’s probably not in our future, though, is a dandelion-inspired parachute for people or their parcels, Braybrook adds. “For us, it’s only as we start to develop [new technologies] that we start thinking about these problems...but nature’s already done the work. Because dandelions can reproduce both sexually (through pollination) and asexually, every seed emerging from a dandelion’s head can have a different genetic makeup. Materials provided by American Physical Society's Division of Fluid Dynamics. www.sciencedaily.com/releases/2017/11/171120090045.htm (accessed November 29, 2020). The genus contains many species, which usually (or in the case of triploids, obligately) reproduce by apomixis, resulting in many local populations and endemism. “For this design to be relevant...you need to talk about objects that are incredibly light or incredibly small,” she says. What wasn’t quite clear, however, was if the seeds’ stability was affected by the number of filaments in each pappus. Dandelion seeds illustrate perfectly the role the wind plays in distributing certain types of seeds across the landscape. Image Credit: Bess Hamitii, Shutterstock. Receive emails about upcoming NOVA programs and related content, as well as featured reporting about current events through a science lens. We conclude that long‐distance dispersal of seeds of herbaceous species with falling velocities < 0.5 ‐ … Dormancy: The seed of dandelion are not dormant and can germinate immediately in the same year that they mature of the plant. Thanks to evolution’s incessant tinkering, these seeds have become some of nature’s deftest dispersers, tumbling inches, feet, sometimes miles from their original source. When upward-bound air travels up and around a falling object, it can create a sort of wobble—a bit like a flag flapping in a gust of wind, just on a much smaller scale. Previous models of the dandelion fruit considered that each parachute filament acts independently, and that the total drag force supplied by the parachute can be found by adding up each of these contributions. American Physical Society's Division of Fluid Dynamics. But as Cummins and his colleagues reported last October in the journal Nature, their pappuses have an especially aerodynamic structure, with bristles so thin that they take up just 10 percent of the total space in the seed’s frizzy updo. And dandelion seeds, it would seem, have a knack for turning nothing into a whole lotta something. To suss out how these strange little structures keep seeds aloft, a team of University of Edinburgh engineers led by Cathal Cummins went into the weeds. Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. This figure matched up with what’s found on real-life dandelions, Gallaire says. Dandelion seeds germinate in emerge from late spring (after flowering and seed dispersal) to early autumn.