[4] Specimens of Eupatorium novae-angliae have been collected for many years, classified by botanists as the more widespread species E. leucolepis, found from Long Island to Texas.

More recent analysis of chromosomes reveals that the New England plants do not appear to be closely related to E. leucolepis.

Eupatorium novae-angliae first formed as a hybrid between two other species, neither of them E. leucolepis.

[2][5][6] It is self-sustaining, rather than being found only where both parents are present, so various authors since 1992 have proposed treating it as a distinct species.

It has opposite, lance-shaped leaves, and flat-topped arrays of a large number of tiny flower heads.