A 10-foot tall plant native to the land between the Black and Caspian seas is spreading through New York state, and officials are warning people to approach with caution. The sap of giant hogweed (Heracleum mantegazzianum) can "cause severe skin and eye irritation, painful blistering, permanent scarring and blindness," according to the New York Department of Environmental Conservation or DEC.
The massive plant looks a little like Queen Anne's lace but on a much bigger scale. The stems can be two to four inches thick and its flowers can grow to two and a half feet in diameter. The leaves are enormous — as much as five feet wide.
First brought to the United States in the 19th century as a garden ornament, hogweed has since spread to 11 states, including Pennsylvania, Washington, Vermont and Maine. According to the New York DEC, it is most prevalent in New York's Oneida County, with large clusters in Niagara, Orleans, Ontario and Cayuga counties. There have been 1,004 confirmed sightings this year in New York.
Touching a hogweed plant might not cause you immediate discomfort, but its sap reacts strongly to sunlight. "You end up with third-degree burns, oozing and scars," Naja Kraus, giant hogweed program coordinator for the DEC, said in a press statement, quoted by LiveScience. "If it gets in your eyes, you can go blind." According to a hogweed fact sheet published by Ohio State University, "Furocoumarins in the sap can cause a skin reaction known as phyto-photodermatitis. This causes the skin to be highly sensitive to ultraviolet light."
The New York DEC has an online identification guide that compares the plant to several look-alike species, and a hotline (845-256-3111) to report hogweed sightings. They have also published some rather graphic photos of hogweed injuries, along with safety precautions to take if you think you have encountered the plant.
Giant hogweed is one of the many plants on the Federal Invasive and Noxious Weeds list. It is illegal to grow, sell or transport the plant because of the threats it poses to human health and native species, which can be crowded out when hogweed takes root in an area.
The U.S. isn't the only country with an invasive hogweed problem. The plant was also recently observed in Guelph, Ontario.