We Totally Underestimated How Terrifying America's Invasive Plants Are

In 2008, M. Night Shyamalan’s veggie-horror film The Happening imagined a world in which pissed-off plants strike back. Though poorly received, the film made an astute observation about our relationship with the plant kingdom: we take everything from them yet are alarmed when they retaliate. A new Nature Ecology and Evolution study, showing the unsettling ability of real-life invasive plant species to take over new environments, suggests we’re in for a rude awakening.

The research team behind the paper, published Monday, show that invasive plants are extremely adaptable to new environments, challenging the long-held assumption that these plants — transported by humans from their original homes to foreign lands — will naturally stay confined to areas suited to their growth. America’s current management strategy, which still results in about $120 billion in invasive plant-based damages each year, assumes we can predict where the plants will grow, but the new study seems to say otherwise.

Dan Atwater, Ph.D., the study’s lead author and a lecturer in the Department of Biological Sciences at North Carolina State University, tells Inverse that the consequences could be dire if we don’t take the plants’ newfound ability into our battle strategy.

“What would happen if the problem worsens? We will continue to lose biodiversity, have continued damage to ecosystem services, and further loss to agricultural production,” he said in an e-mail.

“Sensitive and disturbed ecosystems are always hardest hit.”

America’s invasive plant situation is already quite serious, even with the current interventions the U.S. government is using to manage their spread. Now, as the study suggests, we have to contend with the idea that they can spread even further than we once thought.

In the study, Atwater and his team examined 815 species from every continent, looking at millions of data points showing where the plants originated and where they thrived. What they found was that all 815 of the plants went through “climactic niche shifts” — changes that allowed them to thrive in climates that they wouldn’t normally grow in. The plants that were best at adapting to new environments tended to be those that were intentionally cultivated or were especially long lived.

Many of those plants have already taken over large swaths of the U.S. “I’d say invasive species already have overrun a lot of ecosystems,” says Atwater.

In the American Great Basin, for example, an invasive Eurasian annual grass called downy brome — known by locals as “cheatgrass” — is taking over sagebrush steppe communities. Cheatgrass has been around since the mid-1800s, when it traveled to North America via contaminated grain seed and ballast in ships and quickly took over all the areas where native vegetation had been cut away.

Now, it’s a huge problem in the American West, not only because it swipes the land but since it’s highly flammable and causes wildfires that burn all the native plants. “Left unmanaged, very large regions of the Great Basin are lost,” says Atwater.

Across the Pacific, Hawaii is plagued with an unusual plant called Myrica, known also as fire tree. This is an especially potent plant, says Atwater, because it doesn’t need soil in order to get its fix of nitrogen, an essential element — it just sucks it out of the air.

“That gives it a lot more resources than the native plants, which can’t fix nitrogen,” he says. “Again, this creates a positive feedback accelerating invasion. This species is doing a lot of damage to Hawaii’s ecosystems.”

Unless we want to keep coughing up billions of dollars to deal with the damage these plants cause to lost jobs, poorer ecosystems and agricultural losses, we’d better figure out how to manage them. Currently, the National Park Service’s management strategies include “inventory and monitoring, prevention, early detection and rapid response, treatment and control, and restoration,”

Eating them, unfortunately, is rarely an option, says Atwater. “Wildlife are also often effected because invasive plants tend to be unpalatable and not very nutritious,” he says. “Sometimes they are outright toxic.”

Just as in The Happening, humans can’t blame the plants. Much like us, plants are opportunists that simply take advantage of opportunities to grow and thrive. Some plants, like the greedy moguls among us, are especially enterprising and have no problem capitalizing on weakness. Ultimately, it’s really no one’s fault but ours for decimating all the vegetation in the native landscape, clearing a path for the plant kingdom’s inevitable revenge.

This tiny, deadly worm predates the dinosaurs. Check out this video to find out more.