Native Plant Highlights

What’s in Bloom | White Snakeroot

October 6, 2021

White snakeroot (Ageratina altissima) is a perennial plant in the Asteraceae family that fills woodlands, thickets, forest edges and some old fields in Virginia with white blooms in September and October. The plant can range from 1-4 ft in height and features opposite leaves and flat-topped clusters of flowers. It spreads both by rhizome and seed.

The most common Ageratina in Virginia is A. altissima var. altissima and there are two other white snakeroots less commonly found here: Appalachian white snakeroot (A. altissima var. roanensis) which is known only from higher elevations in the Southern Blue Ridge and small white snakeroot (A. aromatica), which despite its name is nonaromatic.

There are many plants in our region that have earned the common name snakeroot over the years and like many of the others, the root of white snakeroot when prepared as a poultice, was thought to be an antidote to snake bites. It is not considered effective.

In fact, white snakeroot is highly poisonous and in Colonial times, when cattle ate the plant, they not only would get sick but their milk also turned out to be fatal to many humans. For a long time no one could figure out what was causing the sickness (and it was simply called “milk sickness”) until a pioneer doctor, Anna Bixby, realized the seasonal nature of the mysterious disease must connect it to what cattle were eating at the time. As the story goes, she then learned from a Native American woman, nicknamed “Aunt Shawnee,” that white snakeroot was the likely cause. It was not until a century later that American scientists were able to identify the toxic chemical tremetol in the plant.

Benefits to Biodiversity | White snakeroot provides late-season resources to pollinators.

Sources: Flora of Virginia,,

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