Silphium perfoliatum Linnaeus. Phen: Jun-Sep. Hab: Floodplain forests and openings, especially over calcareous substrates; sometimes escaped from cultivation. Dist: VT, ON, and ND south to sc. NC, AL, and TX.
Origin/Endemic status: Native
Synonymy: = F, GrPl, Il, Mi, Oh3, RAB, S, Tn, WV, Perry (1937); = Silphium perfoliatum L. ssp. perfoliatum – Cruden (1962); = Silphium perfoliatum L. var. perfoliatum – Ar, C, FNA21, K1, K3, K4, NE, NY, Pa, SE1, Va; < Silphium perfoliatum L. – G, W