Two years after Abraham Lincoln’s father, Thomas Lincoln, moved his family to the Little Pigeon Creek settlement in Southern Indiana, the family faced tragedy. Abraham was just nine years old when his mother, Nancy Hanks Lincoln, became gravely ill. Just two weeks later, on October 5, 1818, he lost his mother to “Milk Sickness.” Like thousands of other Midwesterners in the 19th century, the Lincolns had no idea why or how a loved one had been poisoned. The culprit was a common woodland plant that cows sometimes consumed if they wandered into wooded areas to graze.

The White Snakeroot (Ageratina altissima) is found throughout Kentucky, Indiana, Illinois, and Ohio. The plant contains the potent toxin temetrol, which when eaten by a cow, results in the milk being poisoned. The chances of contracting "Milk Sickness" today have been greatly reduced due to changes in grazing practices (cows aren’t allowed to graze in woodlands) and by additional safety measures used in the modern dairy industry. Dr. Egbert Fell collected this specimen about 60 years ago. He was the father of George Fell, founder of the Illinois Nature Preserves Commission.