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Recently, species of Joe-Pye Weed have been separated from the Bonesets (Eupatorium spp.); they have been re-assigned to the genus Eupatoriadelphus. Many sources of information will still refer to this species as Eupatorium maculatum. In Illinois, species of Joe-Pye Weed differ from the Bonesets by their whorled leaves, while the latter group of plants have opposite leaves. Spotted Joe-Pye Weed differs from Eupatoriadelphus fistulosus (Hollow-Stemmed Joe-Pye Weed) and Eupatoriadelphus purpureus (Sweet Joe-Pye Weed) by its rather flat-headed panicles of flowerheads, purple-spotted or purplish stems that are often pubescent, and flowerheads consisting of 8-20 disk florets. Other species of Joe-Pye Weed within the state have more dome-shaped panicles of flowerheads, stems that are hairless, and flowerheads consisting of 4-7 disk florets. Spotted Joe-Pye Weed also tends to be shorter.