TALL BONESET (Eupatorium altissimum)

aka Tall Thoroughwort - can be confused with Late Boneset/Thoroughwort
Late Boneset (E. serotinum) has leaves that are wider, have long petioles, and more teeth - see:
http://www.illinoiswildflowers.info/prairie/plantx/late_bonesetx.htm
and http://allthingsplants.com/plants/photo/364439/
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https://www.minnesotawildflowers.info/flower/tall-boneset
says:
Flowers (...) styles are white, flattened, long and string-like. The bracts around the base of a flower are in 2 or 3 layers, green with white edging, and hairy; the inner bracts are oblong and much longer than the outer bracts.
Leaves are 2 to 5 inches long and to 1 inch across, minutely hairy, widest near or above the middle, pointed at the tip with a long taper to the base, and stalkless or nearly so. There are small, widely-spaced teeth in the tip half of leaves but smaller leaves in the upper part of the plant may be toothless. Leaves have 3 conspicuous parallel veins and there are often smaller leaves in the axils. Stems are erect, unbranched except near the flowers, minutely hairy, and green or tinged reddish brown.
If that still isn't enough, there is also False Boneset (Brickellia eupatorioides) that can be confused with other Bonesets (Eupatorium), but closer examination will show the differences.
http://www.illinoiswildflowers.info/prairie/plantx/fs_bonesetx.htm