ELLSWORTH, Maine — They’re big, bold and some might even argue beautiful, in an ostentatious kind of way.
But get too close to specimens of giant hogweed — a type of invasive plant found in about 20 spots around Maine — and you could end up with a permanent reminder of why this weed makes poison ivy or poison sumac seem tame by comparison.
Not surprisingly, state and federal agencies are trying to identify and prevent infestations of a plant once imported for its size and unusual qualities, one of which is, unfortunately, the ability to cause severe burns and blisters.
“It is definitely something we don’t want to get widely established on Mount Desert Island or on the coast of Maine,” said Aleta McKeage, project manager for exotic plant management at Acadia National Park.
A native of the Caucasus region of Asia, the giant hogweed is well named.
Plants can grow to 14 feet tall or higher with leaves several feet long and stems as much as 4 inches thick. But the most remarkable aspect of the giant hogweed is the flower: clusters of white that can measure 2 feet across, typically appearing in summer months.
Because of its flowers, hogweed can sometimes be mistaken for angelica or cow parsnip. But the giant hogweed’s size is the key.
“It’s a really spectacular and very large plant,” said Ann Gibbs, state horticulturalist with the Maine Department of Agriculture. “It is quite a specimen.”
Yet hogweed is not a plant to be messed with. Sap from the plant is an extreme irritant, especially when the affected skin is exposed to sunlight. The results can be painful blisters and burns that can cause permanent scarring.
Gibbs’ agency has documented at least 20 sites around the state with giant hogweed, roughly half of which are in Hancock County. The fact that numerous hogweed sites have been found in Bar Harbor, elsewhere on MDI and in the Ellsworth area is evidence of the plant’s former popularity with estate owners who sought unusual plants from around the globe to fill their large ornamental gardens.
“It is a big, showy plant with a big flower,” said Terry Bourgoin with the U.S. Department of Agriculture’s Animal Plant and Health Inspection Service in Bangor. “I don’t think people realized what the plant could do as far as the chemical reaction.”
Bourgoin said plant specialists with state and federal agencies have been experimenting with several pesticides to try eradicating the plants. But the plant’s flowers generate a large crop of seeds, making control a challenge, he said.
“So if you’re successful at treating the plant, you still have new plants coming up from all of the seeds,” he said.
Acadia National Park has been actively managing several hogweed sites for about three years, McKeage said. Luckily, the sites are not located in areas that would typically get heavy foot traffic.
“There is no way that we want that … in a national park so we try to hit it very hard,” said McKeage, who called hogweed “a real poster child for invasives control.”
Park staff also work with private landowners whose property is found to host hogweed, explaining the threat posed by the plant and steps that can be taken to control or eradicate it.
Gibbs with the Maine Department of Agriculture pointed out that only four new sites have been found recently, so it is not as if hogweed is taking over the state, she added.
The state does not have funding for a hogweed control program, so her department attempts to provide property owners with information about options for controlling the weed. At the very least, property owners can attempt to remove the flower heads before the seeds are released.
But anyone attempting to handle hogweed should take precaution by covering any skin that could be exposed to the sap.
“It’s just like anything: you need to be careful around it and use caution,” Gibbs said.