BAR HARBOR—Giant Hogweed, an invasive plant that is harmful to humans, is being treated with herbicide at Hadley Point Beach, according to a statement issued by the Town of Bar Harbor.
The sap of the plant contains a chemical that can cause “severe dermatitis when skin is exposed to the sun,” according to a fact sheet released by the Maine Department of Agriculture, Conservation and Forestry (DACF). “Sap can also cause eye injury, including blindness.”
Because of these properties, the giant hogweed on Hadley Point is being treated with applications of herbicide, according to the statement from the town. It is expected to “take a number of applications and weeks” before the plant is eliminated. The treatment area is currently roped off to the public.
Similar at a glance to its smaller cousins, including cow parsnip, angelica and the common Queen Anne’s lace, giant hogweed grows to more than twice the size of its nearest relative. Other identifying characteristics are the leaves, up to five feet long and deeply toothed, and the stem that has patches of purple.
“It can be twelve feet tall,” said botanist Jill Weber. “Flower heads can be two and a half feet across. It looks somewhat otherworldly. People are really drawn to it.”
However, Weber cautions against getting close. “It’s really important not to touch the actual plant. It’s more dangerous than poison ivy.”
Giant hogweed was identified and treated once before at Hadley Point, in 2016. “It’s got a ton of seed,” said Jesse Wheeler, vegetation program manager at Acadia National Park, who has been monitoring and eradicating the invasive species on park land.
Giant hogweed has been managed in Compass Harbor and “along the Stanley Brook corridor near Stanley Brook Road,” said Wheeler. Last managed along Stanley Brook in 2018, the giant hogweed population in the park is considered to be suppressed. However, Wheeler welcomes reports from the public if anyone should see it.
Native to the Caucasus region of Eurasia between the Black Sea and the Caspian Sea, giant hogweed (Heracleum mantegazzianum) was imported to North America in the nineteenth century as an ornamental flower. It likely made it to Mount Desert Island when large estates were landscaped. “Plants were brought in from all over the place,” said Weber, noting that many cottagers enjoyed having “showy plants that nobody else had.”
Now recognized as a noxious weed that is not only invasive but also harmful to humans, giant hogweed is no longer used in landscaping. It is illegal to buy or sell. However, the plant has long since escaped the well-kept grounds of old estates, and has entered the natural landscape.
“One plant can produce 100,000 seeds,” said Weber. Seeds can be carried by streams, birds or even the grooves in a hiking boot.“There’s no reason it couldn’t pop up in a different site,” Weber said.
What to do if you see giant hogweed: above all, keep your distance, said Wheeler. He recommends notifying someone. If it’s on public land, notify the organization or municipality. In Acadia National Park, call 288-8722.
If it’s on your own land, Wheeler recommends calling the University of Maine Cooperative Extension or the DACF for information on how to get it eradicated by a state licensed invasive plant manager. Additional information is available at the DACF website.