Eupatorium pubescens Muhlenberg ex Willdenow. Phen: Jul-Sep. Hab: Forests and woodlands, woodland edges, roadbanks. Dist: Primarily in the Appalachians and adjacent provinces, ranging from ME west to OH, south to n. GA, n. AL, AR and LA; the distribution, abundance, and phenology of E. pubescens need additional study because of frequent lumping with E. rotundifolium.
Origin/Endemic status: Native
Taxonomy Comments: Where growing together, E. pubescens apparently flowers about a month earlier than E. rotundifolium. This taxon appears to be a stabilized polyploid complex originating from hybridization of E. rotundifolium and (perhaps) E. sessilifolium; in that it now functions as a more-or-less independent evolutionary lineage, with distinctive morphology, habitat, and distribution, it is here treated as a species.
Synonymy: = F, NE, NY, Va, WV; = Eupatorium rotundifolium L. var. ovatum (Bigelow) Torr. – Ar, C, FNA21, G, K1, K3, K4, Oh3, Pa, SE1, W, Cronquist (1985); < Eupatorium pubescens Muhl. ex Willd. – S, (also see E. cordigerum); < Eupatorium rotundifolium L. – GW2; < Eupatorium rotundifolium L. ssp. ovatum (Bigelow) Montgom. & Fairbrothers – Montgomery & Fairbrothers (1970); < Eupatorium rotundifolium L. var. ovatum (Bigelow) Torr. – RAB, (also see E. cordigerum)