Flowers tiny, a few each in small heads, together forming a large flattish cluster at the top of the plant.  Plant 2-6 feet tall.  Leaves lance shaped, long, pointed, finely toothed,  opposite each other, with no leaf stalks (sessile).  Blooms in the summer.

Rich woods.  Relatively uncommon in the Park.

Members of the genus Eupatorium or Ageratina with white flowers are called bonesets, snakeroots or thoroughworts.  Boneset (E. perfoliatum) has lower leaves that connect across the stalk and likes moist areas. White snakeroot (Ageratina altissima) has wider leaves with long stalks. Late-flowering thoroughwort (E. serotinum) has similar leaves with short stalks and larger teeth. Sweet-scented Joe-Pye weed (E. purpureum) has pale pink flowers and leaves in whorls. False boneset (Brickellia eupatorioides) has leaves that are not opposite each other.