Joe-Pye weed : A tall composite plant of the genus Eupatorium (E. purpureum), with purplish flowers, and whorled leaves.

Example:


Taxonomy
Lamont, Joe-Pye Weed, Eupatorium, Asteraceae, Schilling, maculatum, purpureum, unranked, Eupatorieae, free encyclopedia, genus Eupatorium, Schmidt, Joe, weeds, flower, tribe, Linnaeus, Joe Pye.

Defination from the web:
... Joe-Pye weed. Eutrochium is a genus of herbaceous flowering plants in Asteraceae. They are commonly referred to as Joe-Pye weeds. ... Joe Pye, an Indian healer from New England, used E. purpureum to treat a variety of ailments, which led to the name Joe-Pye weed for these plants. ...