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White Snakeroot: Native Plant With a Fatal Legacy in American History

By Jennifer Correa-Kruegel, Warren County Naturalist

August 15, 2025

White snakeroot (Ageratina altissima) is a native plant that blooms from July through October in large clusters in woods and thickets. Early settlers once believed that its snake-like roots could cure snake bites. That claim was later disproved, but the name endured.

White snakeroot attracts a variety of nectar-seeking insects. Photo by Jennifer Correa-Kruegel.

Clusters of small white flowers top of the plant, resembling Queen Anne’s lace or yarrow. Unlike those flowers though, white snakeroot’s blooms are less lacy than Queen Anne’s lace and less complete a flower than yarrow.

Many insects rely on white snakeroot plant for nectar, while others, such as some leaf miner flies, consume its leaves. Leaf miners tunnel through the leaf tissue, leaving behind squiggly trails as evidence.

White snakeroot is toxic to cows, horses, goats and sheep. When consumed by dairy cows, its toxins can pass into their milk or meat, causing a condition called “milk sickness,” fatal in large quantities.

Milk sickness killed thousands of Americans in the 19th century, including Nancy Hanks Lincoln, Abraham Lincoln’s mother, when he was 9 years old.

Leaf miner damage appears as winding tunnels across a white snakeroot leaf, evidence of insects feeding inside the tissue. Photo by Jennifer Correa-Kruegel.

Although dairy cows may still sometimes consume white snakeroot today it is diluted by nixing it with large quantities of other milk, no longer affecting consumers.

Fun facts:

White snakeroot was once thought to cure snake bites, but it does not.
Insects such as leaf miners tunnel through its leaves.
This plant can poison livestock and cause milk sickness in humans.
Abraham Lincoln’s mother is believed to have died from milk sickness.

Jennifer Correa-Kruegel, Warren County Naturalist

Jennifer has a Masters in Parks and Resource Management from Slippery Rock University. She worked as a Park Naturalist for Hunterdon County Park System from 2003-2006 and then at the NJSOC full-time from 2006 - 2020, starting as the Program Coordinator and evolving to an Environmental Educator. Jen is a New Jersey native and has lived in Warren County with her family since 2004. She is excited to be offering programs to this community she has grown to love.