White Snakeroot, Ageratina altissima, is a poisonous herb that can grow over 4 feet tall and is native to the eastern and central United States. “Ageratina” is derived from Greek and means “un-aging”, as the flowers stay in bloom for a very long time, well into the fall.

In the 19th century, many people became sick after drinking milk. It was eventually discovered that the “milk sickness” was caused by drinking milk from cows who had eaten White Snakeroot, which contains the toxin tremetol.