Ageratina altissima, or white snakeroot, is a poisonous herb found in North America that contains toxic alcohol called tremetol. But just how poisonous is this plant?
Well, back when explorers were first settling Indiana and Ohio in the early 19th century, it’s estimated that up to half of their deaths—including that of Abraham Lincoln’s mother, Nancy Hanks Lincoln—were caused by indirectly ingesting white snakeroot.
Cattle and other livestock in the area would eat the seemingly benign herb would, unfortunately, pass the poisonous tremetol to humans via their milk. The resulting illness was known as fatal milk sickness.