We recently received a question from a patron wanting to find out what type of weed killed Abraham Lincoln's mother. Seeing as today is Lincoln's birthday, we decided to share our findings with you! Abraham Lincoln's mother, Nancy Hanks Lincoln, died of "milk sickness," according to the Abraham Lincoln Birthplace National Historical Park. The root cause of milk sickness was from a plant called white snakeroot--a person is made ill by drinking the milk of a cow that has consumed this plant. The website mentions the disease "was most common in dry years when cattle wandered from poor pastureland to wooded areas in search of food." Nancy Hanks Lincoln died on October 5, 1818 when Lincoln was nine years old.
Anna Pierce, an Illinois doctor, is credited in the book Poisons and Antidotes by Carol Turkington with solving the mystery of milk sickness. The disease killed Anna's mother and sister-in-law, and sickened her father. After a series of observations she "campaigned to prevent drinking milk during the summer" (Turkington 310). A Shawnee woman explained to Anna that white snakeroot was used as a treatment by the Shawnee for snakebites, but it was also the cause of milk sickness (in humans) and trembles (in cows). Unfortunately, Anna tested out this theory on a calf which ended in the calf developing "trembles." Nothing more was mentioned about this calf's fate, but scientists were able to find out what made the plant so toxic to humans and livestock.Turkington writes, "In 1987, scientists discovered that the constituents of snakeroot are not in themselves toxic but are converted to toxic substances by the body's own metabolic processes" (310).
According to the book Wildflowers of the Natchez Trace by Stephen L. Timme and Caleb C. K. Timme, this plant can be found in the wooded areas of Tupelo, MS up to Nashville, TN. Their flowering dates are listed from April through May. While milk sickness is no longer an issue as it was in the 19th century, due to improvements in processing milk, it can still be deadly if consumed directly (which we don't recommend).
Turkington, Carol. Poisons and Antidotes. NewYork: Facts on File, Inc., 1994. Print
Timme, Stephen L. and Caleb C. K. Timme. Wildflowers of the Natchez Trace. Jackson, MS: University Press of Mississippi, 2000. Print
Abraham Lincoln Birthplace, National Historical Park Kentucky: http://www.nps.gov/abli/planyourvisit/milksickness.htm