Eupatorium rugosum was the original name for the ‘white snakeroot’ but due to the toxin it contains, it has been replaced in the Asteraceae family and is now named Ageratina altissima. This plant is native to eastern North America. This plant was observed 2014 September 12 in Newark, Ohio in an open area along the edge of a mixed mesophytic forest with an overstory dominated by Quercus rubra (red oak), Quercus alba (white oak), Acer saccharum (sugar maple), and Juglans nigra (black walnut) and an understory is dominated by Podophyllum peltatum (mayapple), grass and other herbatious plants. This plant was found growing in a moist soil on the south-eastern side of an Acer saccharum (sugar maple) tree. This plant can be best described as a small white flowers in clusters near the top with hair-like tips; opposite leaves (a pair of leaves are attached to a node), ovate (spare-like), and a serrated margin (toothed edge).
I really like the picture on the left. The leaves appear to be ovate in shape with toothed or serrated margins. It also looks as though the leaf venation is arcuate with the leaf apices being acute.