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Physicists discovered a new form of flight thanks to dandelion seeds

As so many of us have done, whether in childhood or as adults, physicists recently blew on a bunch of fine, white dandelion seeds, and made a wish. It came true. They discovered a new, unique element of flight never before documented by scientists.

The dandelion—which derives its name from the French dent de lion, meaning lion’s tooth—may seem like a common weed to be eradicated by vigilant gardeners. But these plants, found in Asia, Europe, and the Americas, are officially classified as perennial herbs, with historical use in both food and medicine. Now, it turns out, they may soon inform human design.

A study published in the journal Nature on Oct. 17 (paywall), written by physicists from the University of Edinburgh in Scotland, reveals that dandelion seeds, which can fly for miles, travel unlike any other kind of seed previously studied. They do this with the help of a detached vortex that appears to propel and stabilize locomotion.

Basically, the dandelion seed floats through the air using a bundle of bristles atop a stalk, called a pappas. That structure acts like a parachute but looks more like the skeleton of an umbrella after the wind has ripped the protective fabric off. The pappas is made of filaments with large gaps between them that allows air to flow up through the bristles and carry the seeds far and wide, propelled by a floating vortex perfectly calibrated to the pappas.

By illuminating the air flow around the flying seeds with lasers, physicists were able to discern the unique mechanics of the pappas. They placed dandelion seeds in a vertical wind tunnel which kept them afloat indefinitely and used long-exposure photography and video to analyze the behavior of the air moving through the pappus bristles. That’s how they discovered the detached vortex ring, an air pocket with a stretched donut shape, floating stably above each pappus.

The porous dandelion pappus consistently contains 90 to 110 filaments (no more and no less). The number of filaments and the gaps between them appear to be tuned precisely to stabilize the locomotive vortex, the researchers say. The vortex floats above the seeds, and the amount of open space between the seed’s spokes are apparently the key to the stability of these detached vortices, study co-author and applied mathematician Cathal Cummins told Nature. Pressure differences between the air moving through the spokes and the air moving around the seed creates the vortex ring.

This design maximizes aerodynamic loading and minimizes material requirements, and the dandelion’s flight mechanism may help illuminate movement in other natural and artificial structures, the researchers say. “The discovery of the separated vortex ring provides evidence of the existence of a new class of fluid behavior around fluid-immersed bodies that may underlie locomotion, weight reduction and particle retention in biological and manmade structures,” the paper states.

In other words, the deceptively pesky and common dandelion is as mighty as its name implies. The “lion’s tooth” offers new clues on how to design things that fly. That’s not bad for the seeds of a plant so many believe is a weed.

How to Get Rid of Dandelions

Searching the yard for white puffballs to blow is a favorite summer pastime for kids, but most adults are more interested in learning how to get rid of dandelions marring a perfect lawn.

It’s understandable. Dandelions are weeds.

Dandelions, which are technically herbs, were first brought to this continent by the colonists, and the yellow flowers and their greens were loved for their numerous health benefits. You can use dandelions to make tea, wine, salads, and other edible side dishes. They are also rich in vitamins and antioxidants.

“One cup of dandelion greens contains almost twice as much iron as spinach and over 500 percent of your daily intake of vitamin K, which may play a role in fighting Alzheimer’s disease,” according to the Michigan State University Extension service’s Michelle Jarvie. “[The] root extract has been shown, in some studies, to fight certain types of cancer.”

Just the same, few people want the spots of yellow and white seed crowns dotting their fields of green.

What are Dandelions?

From the French phrase “dent de lion” or “lion’s tooth,” the dandelion is native to Europe and Asia. This flowering herb is identified by its single yellow flower or white, fluffy seed head that sprouts from a cluster of jagged green leaves.

Quite hardy, dandelions can take root just about anywhere, preferring in places with full sun and temperate climates. And while dandelions pose no risk to the environment — quite the opposite, actually — they can be a menace to your curb appeal.

How to Get Rid of Dandelions in Your Yard

Ridding your yard of dandelions can be extremely difficult. Here’s why: Their taproots reach 10 inches into the soil, and their seeds are carried by the wind to their next location.

Another challenge: Dandelions are perennials, meaning they come back on their own every year.

To remove dandelions you just have to get to the root of the problem — literally. If even a small portion of a dandelion root is left behind, the plant will return.

There are several ways to permanently purge your yard of dandelions, including using a broadleaf herbicide, laying a weed-resistant grass type, or digging up the roots with a dandelion puller.

The best time of year to begin your dandelion removal is fall, as that’s when the plants carry nutrients to their roots for winter storage.

How to Kill Dandelions Naturally

To remove dandelions naturally, you likely will need to get your hands dirty (weeding), do a lot of bending (mulching), or spend a bit of money (reseeding or resodding).

1. Weeding

Weeding may not be the quickest way to rid your lawn of these Irish daisies, but if you only have a few roots to pull, this is the best option. First, wet the soil around the plant to make dandelion pulling easier. As dandelion roots are deep and stubborn, using a tool dedicated to this task will help. Pull from the base of the leaves to ensure you get the entire plant, roots and all. Repeat as necessary.

2. Mulching

Starving dandelions of the sunlight they need to thrive, is another way to kill the plant. Snip the flower and stem, and then, cover the leaves with about 3 inches of mulch. This will block the plant’s energy source and keep it from growing.

3. Reseeding or resodding

Laying down new grass seed (or sod), while drastic but effective, can wipe out existing dandelions and prevent new plants from emerging. Depending on your region, choose a grass type, such as Zoysia, Bermudagrass, tall fescue, perennial ryegrass, or buffalograss. The thick, dense lawns these selections produce crowd out weeds naturally. Maintaining regular lawn care can also help with dandelion control.

4. Using household substances

Unfortunately, there are no truly reliable household remedies for getting rid of dandelions. Despite what you may have heard, neither salt, boiling water, dishwashing soap, apple cider vinegar, nor white vinegar are good options.

Why these aren’t good options: Salt and boiling water can wash all over your yard, potentially killing other plants in their wake. Dishwashing soap may dry out leaves but won’t reach the roots. And, for vinegar to work, it needs to be horticultural vinegar, which is dangerous to handle.

Applying Chemical Treatments to Kill Dandelions

Broadleaf herbicides do a great job of terminating dandelion populations. Spray the plants with the weed killer of your choice during the fall months, and the toxins will travel, along with the nutrients, down to the roots.

There’s a chance you may have to mist on a second application before the weed is completely killed. If it’s already spring, no worries. Early spring is the second-best time to get rid of dandelion plants.

Use the same pre-emergent solution you’d use to get rid of crabgrass, such as Roundup, to kill these lawn weeds before their seeds germinate.

When to Call a Professional

If you’ve tried all these options to no avail or you’re thinking to yourself, “These tips are nice, but I’ve got waaaaay more dandelions than one person can handle,” it’s time to call in the lawn care professionals.

Or… Maybe you will decide those dandelions aren’t that unsightly for all of the health benefits they offer. Dandelion tea, anyone?

After all, dandelions can be a draw for your lawn.

According to Ken Willis, head of horticulture at the University of Alberta in Canada, dandelions are excellent at attracting pollinators, such as bees, butterflies, moths, and birds.

Main image credit: Markus Winkler / Unsplash

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Andréa Butler

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