American Water Hemlock
Also know as cicuta maculata. This plant is native to temperate areas of the Northern Hemisphere, and is identified by having small green or white flowers hanging in an umbrella shape. It is considered one of America's most toxic plants to humans.
Government Printing Office Yearbook of the United States Department of Agriculture (Washington, D.C.: Government Printing Office, 1897)
Courtesy the private collection of Roy Winkelman