Eutrochium

Eutrochium is a North American genus of herbaceous flowering plants in the family Asteraceae. They are commonly referred to as Joe-Pye weeds. They are native to the United States and Canada, and have non-dissected foliage and pigmented flowers. The genus includes all the purple-flowering North American species of the genus Eupatorium as traditionally defined, and most are grown as ornamental plants, particularly in Europe and North America.

==Taxonomy== Eupatorium has recently undergone some revision and has been broken up into smaller genera. Joe Pye weeds were initially included in the genus Eupatorium, but as early as the 19th century Franco-American botanist Constantine Samuel Rafinesque proposed separating them into their own genus Eutrochium. Unaware of this, research botanists Robert M. King and Harold Robinson proposed assigning them to a new genus Eupatoriadelphus in 1970. This was widely accepted, and Joe Pye weeds began to be referred to as such.