Ageratina altissima)

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Ageratina altissima, White snakeroot, from Flora of North America

Taxonomy and Systematics

Kingdom: Plantae

Subkingdom: Tracheobionta (Vascular plants)

Division: Magnoliophyta (Angiosperms)

Class: Magnoliopsida (Dicots)

Subclass: Asteridae

Order: Asterales

Family: Asteraceae

Genus: Ageratina Spach

Notes on taxonomy: This species was designed as Eupatorium altissimum by Linnaeus in 1753. In 1841, the French botanist Edward Spach first suggested the separation of the Ageratina genus from the Eupatorium. The current name was given in 1970 by R. M. King and H. Robinson.

Although species of Ageratina bear a close superficial resemblance to species in the Eupatorium genus, genetic evidence suggest that they are not nearly as closely related as they appear.

Species of the Ageratina can be visually distinguished from Eupatorium by the imbrication or layering of the latter's involucral bracts into two or three series.

Descriptive notes

A. altissima (White snakeroot) is a composite with receptacles containing eight or more white flowers each. It bears opposite, coarsely serrate, petiolate leaves.

Campus distribution and habitat

Found in high shade forest undergrowth.

General distribution

Grows throughout New England, excluding much of coastal Maine

Other notes

White snakeroot is poisonous and its poison can be transmitted through the ingestion of the milk or meat of cattle that have eaten the plant. Its effects are called "milk sickness" and were responsible for the deaths of many early settlers.

Other resources


  • Magee, Dennis W. and Harry E. Ahles. Flora of the Northeast: A Manual of the Vascular Flora of New England and Adjacent New York. Amherst: University of Massachusetts Press, 2007.

External links