The names sounds like a bad science fiction movie title, Giant Hogweed. Introduced into the United States in 1917, it is a dangerous and noxious plant. As the NYS Department of Environmental Conservation says “Do not touch this plant!”
The giant hogweed is an herb in the carrot family. It can grow to a height of fifteen to twenty feet. The New York State Department of Health warns
Giant hogweed makes an impressive appearance because of its height, and the size of the leaves and flower clusters. But it may spell trouble for people who are sensitive to the plant sap, a clear and watery fluid. The combination of sap on the skin and exposure to sunlight can produce painful, burning blisters within 24-48 hours. Contact with the plant sap can also result in purple or black scars.
The sap is activated by sunlight. If you come into contact with the plant, wash thoroughly with soap and water. Avoid sunlight. Call a physician for a severe reaction. A steroid cream may be prescribed. The plants or plants should be removed by professionals. In New York, call toll-free 1-845-256-3111 for more information and to report the location where you saw giant hogweed.
Here is a map showing where the giant hogweed has been found in Canada and the United States. Contact your state or provincial government for information for your area.