Avoid this plant at your local garden center. It’s ‘world’s most invasive weed’

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If you’re thinking of buying this plant variety to spruce up your yard ― don’t.

Cogongrass is one of the “world’s most invasive weeds,” says the United States Department of Agriculture.

It’s banned in the United States by the Federal Noxious Weed Act and is found primarily in the Southeastern states, but is making inroads elsewhere.

At least 33 vendors in 17 states continue to sell this toxic plant species, a new study by the University of Massachusetts Amherst found.

Cogongrass, also known as Imperata cylindrica, is “the most concerning case of federally designated noxious weed sales,” said Evelyn M. Beaury, lead author of the study and graduate student in organismic and evolutionary biology at UMass, in a news release.

“This is a tricky case because plant breeders are marketing a sterile cultivar (they can’t reproduce in the wild). But research shows these plants are not completely sterile and can still become invasive,” she added.

Cogongrass produces upright stems up to 4 feet tall and seeds are usually dispersed by the wind, but roots can also spread to other places on cars and equipment, according to the Southern Regional Extension Forestry.

Confirmed in July in Arkansas

Although native to Southeast Asia, cogongrass was accidentally introduced in 1912 in Mobile County, Alabama, “as packing material for oranges from Japan,” according to the USDA. It was later introduced to Florida and other states as a potential forage crop in the 1930s and ‘40s, according to the University of Florida. But the crop backfired and started to overwhelm native vegetation.

Now it’s taken up several thousand acres in the Southeastern U.S., according to the Mississippi Forestry Commission. It is most prevalent in Alabama, Florida, Georgia, Louisiana, Mississippi, Oregon, South Carolina, Texas, and Virginia.

It was also confirmed for the first time in Arkansas this past July, the USDA said.

But it’s not just cogongrass that’s hurting native plants, the researchers said.

Many invasive plants for sale in U.S.

The study, published in Frontiers in Ecology and the Environment, found that current regulatory and ethical guidelines don’t limit the sale of invasive plants ― with more than 60% of 1,285 plants the researchers identified still on the market in the U.S..

Researchers looked at Google and nursery catalog databases to identify which invasive plants were sold in the U.S. They then recorded where these plants were sold and how many vendors were selling them across the lower 48 states despite state or federal regulations.

“Once we’ve recognized that an ornamental plant can be invasive, we would hope that commercial sales of that species would stop,” Beaury said in a news release. “But our findings show that our current framework for removing invasive plants from plant trade isn’t working.”

“States are generally doing a good job limiting sales of their own regulated plants, but we found major inconsistencies in what’s being regulated across state borders,” Beaury said. “Nearly all states had at least one of their regulated plants sold in a neighboring state.”

About 50% of state-regulated and 20% of federal invasive weeds were being distributed across large online marketplaces like eBay and Amazon — where people can easily ship invasive plants across state borders with little or no consequences, the study found.

“While patchy state regulations definitely contribute to the widespread availability of invasive plants in the U.S., it’s clear we as a public also lack awareness about which plants are invasive and how they spread to new areas,” researchers said in a news release.

Beaury and her team suggest that more consistent regional oversight, better coordination “among states at regional and national levels,” and conducting outreach to growers and consumers could help reduce propagation of invasive plant species.

“We’ve known for decades that many gardening and landscaping plants are invasive, but we’ve done little to stop propagating them,” said Bethany Bradley, senior author and professor of environmental conservation at UMass, in a news release.

“We can do better,” Bradley said.

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