FYI Eupatoriadelphus vs. Eupatorium
Some of you are probably aware of this but I just came across it. The Joe Pye weeds are now classified at Eupatoriadelphus sp. as opposed to the old name Eupatorium. This is to separate them from the Bonesets. The difference being that Eupatoriadelphus has whorled leaves, while the Eupatorium has opposite leaves (according to the U of Texas, at Austin, Ladybird Johnson wildflower website). I will be checking this out on my rounds :).