Eupatorium torreyanum Short & R. Peter. Phen: Late Jul-Oct. Hab: Dry woodlands, powerline rights-of-way, roadsides, marshes. Dist: NY south to n. peninsular FL, Panhandle FL, and west to OH, TN, and LA.
Origin/Endemic status: Endemic
Taxonomy Comments: Cronquist (1980) considers this taxon a "well-marked variety", "probably originated through hybridization between E. hyssopifolium and some other species, but now a stable entity". The other parent is postulated by Sullivan (1978) to be E. semiserratum. For reasons stated in the comments before the species accounts, the taxon is here treated as a species.
Synonymy: = K4, NE, NY, S, Tn, Va; = Eupatorium hyssopifolium L. var. laciniatum Gray – Ar, C, F, Fl7, FNA21, G, K1, K3, Oh3, SE1, W, WH3; < Eupatorium hyssopifolium L. – Pa, RAB