5b. Silphium perfoliatum Linnaeus var. perfoliatum
Stems glabrous, hispid, or scabrous. Peduncles usually scabrous to hispid. 2n = 14.
Flowering summer–early fall. Wet prairies, open forests, and river bottoms; 50–500 m; Ont.; Ala., Ark., Conn., Ill., Ind., Iowa, Kans., Ky., La., Mass., Mich., Minn., Miss., Mo., Nebr., N.J., N.Y., N.C., N.Dak., Ohio, Okla., Pa., S.Dak., Tenn., Tex., Vt., Va., W.Va., Wis.
