The fig buttercup looks harmless, its tiny yellow flowers and wide green leaves seemingly perfect for a garden bed or patio pot. Even its name sounds pleasant. But Maryland officials say it is one of the most destructive plants in the state, an invader that wipes out native species, strangles forests and smothers fields.
That is why, starting next year, sales of fig buttercup will be illegal in Maryland, along with sales of shining cranesbill and yellow flag iris. This month, garden centers and nurseries in the state began posting signs next to five other invasive species — burning bush, border privet, Chinese wisteria, Japanese wisteria and an Asian wisteria hybrid — warning that the plants may take over and endanger other species once they are planted.
The state Agriculture Department’s Invasive Plants Advisory Committee plans to evaluate 28 other species in coming years.
Invasive plants are species that are not native to an area and cause environmental or economic harm. They eliminate native plants in a variety of ways: blocking sunshine, sucking up all the water or climbing to the tops of trees until their hosts become top heavy and topple. In the process, the invaders disrupt delicate ecosystems. Local deer and birds, for example, generally will not eat the invasive plants and instead compete for a shrinking supply of native plants, leaving the spread of invasives unchecked.
Many invasive plants were imported to the United States as ornamentals for private gardens or as low-maintenance options for government projects, said Carole Bergmann, a forest ecologist with the Maryland-National Capital Park and Planning Commission. Parks and governments used invasives for erosion control and as windbreaks and cover for highway medians until the mid-1990s, when scientists noticed the damage the plants were causing.
The same characteristics that make such plants attractive — minimal upkeep, hardiness and the ability to spread quickly— are what make them difficult to remove from natural environments.
Even when theoretically contained to a private garden, invasives spread when uprooted plants are tossed over the back fence and into a park, Bergmann said, or when a bird eats the seed of a plant before dropping it in a forest miles away. In the process, whole landscapes have been transformed.
In the 10 years that she has led educational nature walks, Kirsten Johnson, co-president of the Maryland Native Plant Society, has seen fields and forests that once hosted native wildflowers mutate into “acre after acre, mile after mile” of fig buttercup.
“There are areas that, frankly, we wouldn’t bother to do a field trip in anymore because it’s all invasive species,” she said.
The U.S. Forest Service estimates that invasive plants can be found on 133 million acres of federal, state and private land across the country — as much land as California and New York combined. Every year, the plants claim about 1.7 million more acres.
The U.S. Agriculture Department bans the importation and interstate transportation of more than 100 plants species that are invasive. But most regulations are left to the states, because the species and ecosystems differ.
Although Maryland’s rules began to take effect only this year, other states implemented sales bans years ago, and their lists have expanded.
Texas prohibits the sale of 3 2 invasive plant species, New York bans 68 and Massachusetts bans 137. As a preventative measure, Virginia banned the importation and growth of eight invasive plants before they became a widespread problem.
A few garden retailers in Maryland stopped selling invasive species out of concern for their negative impact on the environment, even before the state regulations were created.
Behnke Nurseries in Beltsville has gradually eliminated dangerous invasive species from its stock over the past decade, said Miri Talabac, a plant buyer for the nursery. The change has caused little trouble for the business, she said, and any customer hoping to buy a species that is invasive can usually be redirected to a native alternative.
“We all have a financial responsibility to our business, but we know the species have a negative impact,” Talabac said. “I always want to be a moral leader in this.”
Lilypons, a store in Adamstown, Md., that specializes in aquatic plants, stopped selling yellow flag irises in the fall in anticipation of the new regulation. Operations manager Jon Sander estimated the change will cost the store about $1,000 a year — a small percentage of the company’s revenue. But he said he fears further losses as the Agriculture Department adds more species to its list.
“Now that the door’s kicked open it’s going to be a lot less work for them to get the next species, the next dozen species, the next 200 species on the list,” he said.
But some environmental advocates said the new rules are too little, too late for the thousands of acres already host to invasives.
“These laws just don’t address what’s already out there on the ground,” said Kerrie Kyde, an invasive-plants ecologist with the Maryland Department of Natural Resources. “But these rules are ways to stop the next problem from happening.”
Johnson said the new regulations are a good way to educate people about the harm from invasive species but might not be enough to stem the loss of native species, such as the spicebush swallowtail butterfly or the state’s wildflowers.
Bergmann, the forest ecologist, said there are at least a dozen other species she would like immediately banned from retail sales, such as the Asiatic bittersweet vine. The vine, commonly used to decorate in the fall, climbs up trees from grasslands and wraps its four-inch-wide tendrils around the trunk, choking the tree until it dies.
“I’d like to take a bigger step, but I understand that this is how we get things done,” Bergmann said. “You’ve got to start somewhere, even if this is a long time coming.”
Mike Hemming, a member of the Invasive Plants Advisory Committee and the owner of Eastern Shore Nurseries in Easton, Md., said it takes between 30 and 50 hours to evaluate each invasive plant and categorize it.
The committee, largely made up of volunteers, spent more than four years formulating its recommendations; members had to consult with scientists and other states to make sure their classification process was thorough.
“It’s not perfect, but it never will be perfect,” Hemming said. “You can’t write a perfect law.”
The regulations will change little for those on the front lines of the battle against invasive plants, such as the 600 “Weed Warriors” who spend their free time rooting out invasives in Montgomery County parks.
Sarah Morse, executive director of the Little Falls Watershed Alliance and a Weed Warrior volunteer since 2006, has led hundreds of volunteers in Little Falls Stream Valley Park, next to her Bethesda home. Together, they have reclaimed chunks of the park from invasives such as fig buttercup, bush honeysuckle and English ivy.
There are rewards for the unending work, she said, such as a park meadow where native wildflowers bloomed this summer for the first time in years.
But in the end, one meadow is just a tiny fraction of the work to be done.
“When I drive down the road, I can’t help but think of all the wildflowers I don’t see,” Morse said. “They should be there, but they aren’t.”