On a recent day, Suzanne Vautier leads volunteers into the Rough and Ready Botanical Wayside, in Oregon’s Illinois Valley, about an hour from Grants Pass.
The crew is armed with miners’ picks, plastic bags, and orange flagging stamped “NOXIOUS WEED.” They fan out into the brush, searching for a new invasive flower. It’s a tall, bushy perennial called Yellow Tuft Alyssum.
“In the case in the case of alyssum, we have a plant that’s toxic to animals, that’s spreading, endangering plants in our rare areas,” Vautier says.
Vautier is a native plant enthusiast from Cave Junction, Ore. She works for the state Department of Agriculture’s noxious weed removal team.
The soil in the Illinois Valley and the nearby Kalmiopsis Wilderness is made of a rare type of rock called serpentine. As a result, unique plants have evolved in the area, and many species only grow on serpentine soils in Southern Oregon and Northern California.
Invasive yellow tuft alyssum came from similar soils in Southeast Europe and Turkey. Botanists worry this variety of alyssum could crowd the native flowers out.
Kelly Amsberry is part of the Oregon Department of Agriculture’s Native Plant Protection team.
“It’s a big vigorous plant. It doesn’t have any enemies here or anything else that might compete with it directly. It has the potential to go across that serpentine soil, and make huge stands,” she says.
Some invasive species are hitchhikers, brought by accident in suitcases and cargo containers. Other species, like Himalayan blackberry and scotch broom, have been introduced to the Pacific Northwest by nurseries and farms that didn’t understand the species had a potential to escape into the wild.
Yellow tuft alyssum may the only invasive plant that was introduced in a mining experiment.
When Richard Roseburg began working with yellow tuft alyssum fifteen years ago, it was promising plant with a special power.
Several closely-related species of European yellow alyssum plants absorb nickel from the soil and concentrate the metal in their leaves.
“The idea that we maybe could produce an important industrial metal without tearing the tops off of mountains, that’s what really intrigued me,” says Roseburg, a soil scientist with Oregon State University.
Yellow tuft alyssum plants have specially adapted to metal-rich serpentine soils in Europe. By storing nickel metal in their leaves, alyssum species may help fend off predators.
“They’re very very distasteful, they’re very bitter. Animals typically won’t eat them, insects typically won’t visit them,” Roseburg says.
Plant species like yellow tuft alyssum are called “metal hyper-accumulators,” and have been used with some success to clean up mining tailings and other types of environmental contamination.
In 1995, researchers proposed doing something more radical: using dense fields of yellow tuft alyssum plants to extract nickel in a process they called phyto-mining.
In 1997, Roseburg was invited to join a research partnership that included U.S. Department of Agriculture Research Service, the University of Sheffield in England, the University of Maryland, and private investors.
The team collected yellow tuft alyssum seed from serpentine soils Southern Europe and Turkey, where the plant is native. Early experiments with plantings in Maryland didn’t produce much nickel, so the team decided to bring Yellow Tuft Alyssum to Southern Oregon — one of the only places in the U.S. with nickel-rich, serpentine soil.
HILBURN 9-08-1997 Letterhead A letter addressed to the Oregon Department of Agriculture describing Yellow Tuft Alyssum and the proposed research.
In 1997, Roseburg helped plant about half a million seeds in a small field near Cave Junction in Oregon’s Illinois Valley.
Rufus Cheney, the lead USDA researcher on the project, notified the Oregon Department of Agriculture by letter of the experimental plantings. He wrote that the yellow tuft alyssum species were unlikely to cause any problems.
“To illustrate the low risk these plants comprise in North America, when we brought Alyssum species seeds into the U.S., the USDA Animal and Plant Health Inspection Service evaluated the situation and allowed us to bring the seeds directly to Beltsville,” Cheney wrote.
Roseburg says the alyssum was mowed, baled like hay, and then burned. The ash was sent to a nickel refinery for testing.
“It had a high enough nickel concentration that you could extract on the order of several hundred pounds of nickel, per acre, every year,” he says.
Roseburg says there was one key step in the process. The alyssum has to be cut before it flowers because he plant drops its leaves and loses its nickel when it blooms. Cutting the alyssum before it blooms limits the risk of seeds escaping into the wild.
Some plants were allowed to flower and produce seed in breeding experiments. Roseberg says for several years he monitored those areas carefully, walking the perimeter to look for escaping plants; he didn’t find any. In 2002, according to state documents, Roseberg completed a new crop evaluation for yellow tuft alyssum and wrote that it was not likely to spread “across the serpentine landscape in an uncontrolled manner.”
The research collaboration was funded by a Texas company called Viridian Resources. In 2002 Viridian stopped paying for the team’s research and began to expand the alyssum plantings on its own.
Viridian leased land from local farmers and the county airport. It planted nine fields with alyssum. The company did not respond to repeated requests for comment.
Suzanne Vautier says Viridian’s largest alyssum field was about 50 acres, and that the company allowed the alyssum to flower and produce seed. Concerned, Vautier began photographing the fields and keeping detailed notes.
“They weren’t being as careful in their practices as they could have been. They weren’t mowing it and bailing it until after it was in flower.”
Vautier and other locals say Viridian did not follow best management practices that limit the likelihood crop species will escape into the wild. She says Viridian left bales of alyssum and piles of seeds uncovered and didn’t wash its trucks and farm equipment.
“When I went to look at the equipment it was just covered in alyssum seed,” she recalls. “And they were also taking the equipment to a number of locations. So that was kind of concerning. Is anybody going to wash the vehicle off to remove this plant matter?”
Vautier and Forest Service botanists noticed alyssum plants escaping the fields. The tall, yellow flowers showed up along roadsides, on the banks of the Illinois River, and on to federal Bureau of Land Management and Forest Service land.
In 2009, the Oregon Department of Agriculture agreed to conduct a formal weed assessment for yellow tuft alyssum. Kelly Amsberry worked on the assessment. She says the results were alarming.
“We calculated the number of seeds produced per plant and it’s huge,” she says. “Hundreds if not thousands of seeds per plant. Most of which germinate, and they’re easily dispersed.”
The assessment found that alyssum seeds could germinate after floating and could be spread by the wind and water. The metal in the leaves makes the plant potentially toxic and harmful to wildlife and livestock.
In 2009, Oregon declared Yellow Tuft Alyssum a noxious weed and a top priority for eradication. Viridian fought the listing, but eventually agreed to contribute 20,000 to survey and eradication work.
To date, the Forest Service and the Department of Agriculture have spent $300,000 trying to eradicate alyssum. The Forest Service is particularly concerned the plant could spread into the Rogue River Siskiyou National Forest and the Kalmiopsis Wilderness area.
State botanist Kelly Amsberry says she’d like to see tighter scrutiny of experimental crops before they are planted.
“I think that before any crop gets planted in Oregon, or anywhere else that’s completely new; it should be evaluated for the potential for weediness,” she says.
In a field near the Rough and Ready Botanical wayside, Suzanne Vautier’s crew of volunteers finds hundreds of alyssum seedlings mixed in with the native grasses.
“This soil is very, very rocky, so we use miners picks a lot, to get enough of the root up so that you kill the plant,” she says.
Vautier says she’s optimistic the eradication effort will be successful, because alyssum hasn’t yet spread beyond the Illinois River Valley.
“One of the reasons why I really want to work on this plant so much and this problem here is because it’s in a limited area, and really the window to do anything about it is now. If we don’t get rid of it in the next couple of years, it’s going to be too far gone and we won’t be able to do anything about it.”
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