Sep 25, 2023
The dangers of climate change threaten species the world over. There’s at least one type of plant, though, built to thrive on our warming planet. Unfortunately for the 80% of humans that are violently allergic to it, that plant is poison ivy.
"My heavens to Betsy, it's taking off," Jacqueline Mohan told NPR. She’s an ecology professor at the University of Georgia. "Poison ivy takes off more than any tree species, more than any shrub species,” she added.
Mohan’s team studies the effects of climate change on plant species in the Harvard Forest of central Massachusetts. In a recent experiment, they artificially warmed the top layer of soil in a patch of forest by 9 degrees Fahrenheit. Then, they observed the effect on plants. Poison ivy was the winner. The heat benefitted a fungus with which the ivy has a symbiotic relationship.
Another study pumped carbon dioxide (CO₂) into a stand of trees and shrubs. It mimicked greenhouse gas levels as they’re predicted to be in 2050. Most plants absorb CO₂ like humans do oxygen. Thus, all the plants in the stand showed signs of growth. Trees, for example, grew 18% faster. And poison ivy? A whopping 70%.
William Schlesinger of Duke University was the lead researcher. He said, "It was the max. It topped the growth of everything else."
Perhaps most irritatingly, the affected ivy plants in both studies produced a more potent form of urushiol. That's the oil that causes allergic humans to break out in a red, painful rash.
As the planet warms and poison ivy spreads, the best prescription to prevent the itchies remains avoiding the plant entirely. Look out for vines with wide, pronged leaves in clusters of three.
Photo from Flickr courtesy of Lana Pahl.
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