Nicole van Dam
Nicole van Dam

Plants Tailor Their Chemical Weapons to Match Their Opponent

Nicole van Dam
Nicole van Dam

Plants look so helpless and innocent, leafing about in their fields and lawns, but mess with the wrong one and you could find yourself in a world of pain. Scientists say some plants can identify their herbivore attackers—and that the plants use that information to call in bigger, herbivore-killing bugs. A report on the findings was published in the journal New Phytologist.

The arms race between plants and plant-eaters is both brutal and surprisingly advanced. To combat opponents that can bite, pinch, fly, crawl, and run, plants have developed an impressive suite of chemical weapons. Some of these weapons are poison; others simply make the plants taste awful. And then there are the wasp calls. When under attack, some plants emit volatile gases that act almost like dog whistles, silently summoning gangs of parasitic wasps to take care of the offending insect.

Even without the benefit of external sensory organs, plants can tell when they’re being assaulted. Previous studies have found that some plants can sense their attackers’ odors in the air. Others ‘listen’ for the chemical distress calls emitted by nearby plants. Still others pick up on chemicals in a slobbering bug’s saliva.

So lots of plants can tell when they’re being eaten, but can they tell who’s doing the eating? To find out, researchers paired field mustard (Brassica rapa) plants with 12 different herbivore species, including caterpillars, aphids, and a slug. Some species were gnawers and chewers, while others fed via sucking. Some were local and some were unfamiliar. The researchers covered each plant/pest pair with a plastic bag to collect any gases the plants emitted, then tested the gas.

The plants were having none of it. They fought back admirably against all 12 attackers, producing different compounds for each species in order to summon the right species of wasp. The gases all contained the same chemicals; the plants simply adjusted the ratio of chemicals to customize each cocktail. They even concocted successful blends to dispose of species they’d never met before.

Lead author Nicole van Dam says the findings are “spectacular proof” of plants’ hidden capabilities. “The plants may not have a nervous system, eyes, ears, or mouths,” she said in a statement, “but they are capable of determining who is attacking them. What I find truly amazing is that they’re even capable of distinguishing between a native and an exotic herbivore.”

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Watch a Tree Release a Massive "Pollen Bomb" Into the Air
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iStock

In case your itchy, watery eyes hadn't already tipped you off, spring is in the air. Some trees release up to a billion pollen grains apiece each year, and instead of turning into baby trees, many of those spores end up in the noses of allergy sufferers. For a visual of just how much pollen is being released into our backyards, check out the video below spotted by Gothamist.

This footage was captured by Millville, New Jersey resident Jennifer Henderson while her husband was clearing away brush with a backhoe. He noticed one tree was blanketed in pollen, and decided to bump into it to see what would happen. The result was an explosion of plant matter dramatic enough to make you sniffle just by looking at it.

"Pollen bombs" occur when the weather starts to warm up after a prolonged winter, prompting trees and grasses to suddenly release a high concentration of pollen in a short time span. Wind, temperature, and humidity levels all determine the air's pollen count for any given day, but allergy season settles down around May.

After determining that your congestion is the result of allergies and not a head cold, there are a few steps you can take to stave off symptoms before they appear. Keep track of your area's pollen report throughout the week, and treat yourself with antihistamines or nasal spray on days when you know it will be particularly bad outside. You can also keep your home a pollen-free zone by closing all the windows and investing in an air purifier. Check out our full list of seasonal allergy-fighting tips here.

[h/t Gothamist]

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Why Some Trees in Norway Are Missing Their Rings
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iStock

Dendrochronologists are experts at reading tree rings. They can learn a great deal of information—including past climate in an area and the age of the tree—by taking a tree core sample and reading between the lines (literally).

But as the BBC reports, one climate researcher was stumped when she discovered that many trees in the Norwegian village of Kåfjord were missing their rings. Extreme weather and invasive insects can cause some degree of damage to trees, but not enough to render them ringless.

Claudia Hartl, from Johannes Gutenberg University in Germany, knew that these trees dated back to 1945, but that alone wasn't enough information. Two other clues that helped Hartl and her colleagues solve the mystery were location and history. During World War II, Nazi soldiers moored the Tirpitz—the largest battleship of Hitler's navy—off the waters of Kåfjord to intercept vessels carrying Allied supplies to the Soviet Union. The Germans released an artificial smoke containing chlorosulphuric acid to conceal the ship's location, and this is believed to be the root of the trees' problem.

Artificial smoke could have damaged the needles of the trees, halting the photosynthesis process and stunting the trees' growth, researchers found. It takes time for the trees to recover, but it is possible. One tree saw no growth at all from 1945 to 1954, but after 30 years its growth had returned to normal. Hartl presented the findings at the European Geosciences Union General Assembly in Vienna this week [PDF].

"I think it's really interesting that the effects of one engagement are still evident in the forests of northern Norway more than 70 years later,” Hartl told BBC News. She believes her "warfare dendrochronology" will unearth similar findings elsewhere in the world.

[h/t BBC News]

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