any of a number of perennial American plants (genus Eupatorium) of the composite family, with whorled leaves and clusters of rayless, pinkish or purple flower heads
See joe-pye weed in American Heritage Dictionary 4
(jōˈpīˈ)
noun
Any of several tall North American plants of the genus Eupatorium, having whorled leaves and terminal clusters of small pinkish or purplish flower heads.