Ageratina altissima

The shade of the forest floor seems to brighten for a time when the white snakeroot blooms, with clusters of white flowers appearing in luminous relief above dark green foliage. The timing of the flowering period makes white snakeroot an important resource for pollinators as summer transitions to fall. Small species of butterflies show a special affinity for white snakeroot, and other insects including moths, flies, wasps, and bees also utilize the plant.

A good competitor, white snakeroot is a major nonwoody constituent of forests throughout much of the eastern US, including Ohio. The plant is well adapted to disturbed landscapes and is a common volunteer in backyards, vacant lots, and other urban spaces, where it spreads through airborne seeds as well as underground stems. White snakeroot is tolerant of full sun through shade, but grows best under partial shade in soils of average to moderately dry moisture. One to four feet in height and resistant to mammalian herbivory, white snakeroot is a robust and handsome addition to the shade garden.

In natural areas that transition from sun to shade, such as forest edges, white snakeroot tends to occupy the shadier portions and its close lookalike, late boneset, the sunnier. The two plants share a late season bloom and distasteful foliage from the standpoint of deer. The latter quality is especially useful in the case of white snakeroot due to the tendency of deer to browse on woodland goldenrods and asters, the other showy late-blooming shade plants.   

References: 1,2,3,4,5,6,7.

Photo by Julie Slater.