Joe Pye Weed
Joe pye weed (Eupatorium fistulosum (Eupatoriadelphus fistulosus))
Note the large central cavity (hollow space) in the stem of Eupatorium fistulosum. This is one of the best diagnostic differences between E. fistulosum and E. purpureum, which has a much smaller hollow space in the center of the stem. Other detectable differences between these two species is that in E. fistulosum the stem is fairly covered in purple/red, while in E. purpureum this color is somewhat limited to the nodes. Also E. fistulosum tends to grow at more lowland wetter areas, compared to E. purpureum which can be found in higher and drier locales.