White Snakeroot
Scientific Name: Ageratina altissima
Category: plant
Brief Description
A perennial woodland wildflower with branching stems, opposite, toothed, oval leaves, and small clusters of bright white composite flower heads.
Characteristics
Stems are upright and branching, growing up to 1.5 meters tall. Leaves are opposite, petiolate, ovate, and coarsely serrated with pointed tips. Flowers are pure white, fluffy-looking clusters that appear in late summer to autumn.
Habitat
Shaded areas, rich deciduous woods, thickets, woodland borders, and along shaded streams or ravines.
When to Find It
Blooms from mid-summer through frost (July to October).
Conservation Status
Secure / Common
Ecological Role
Provides late-season nectar for various pollinators including native bees, butterflies, and small wasps.
Easily Confused With
Can be confused with other white-flowered asteraceous woodland plants such as boneset (Eupatorium perfoliatum), but white snakeroot has distinctly stalked leaves rather than perfoliate leaves.
Observation Tips
Look for its clusters of small white flowers in shaded understories during late summer and autumn.
Interesting Facts
Famous for containing tremetol, a toxic alcohol that passes into the milk of cows that graze on the plant. Humans who drink the contaminated milk can contract 'milk sickness', a severe and often fatal poisoning that famously caused the death of Abraham Lincoln's mother, Nancy Hanks Lincoln.
User Notes
In Nebraska