Silphium radula Nuttall. Phen: May-Aug. Hab: Prairies. Dist: MO south to TX and LA. Sometimes reported as occurring east of the Mississippi River (as by Jones & Coile  for nw. GA), but there appears to be no authoritative evidence to support that. Found in MS (John Kees, pers.comm. 2022).
Origin/Endemic status: Native
Synonymy: = GrPl, K1, NcTx, SE1; = n/a – C, F; = Silphium radula Nutt. var. radula – Ar, FNA21, K3, K4; > Silphium reverchonii Bush – Perry (1937)