Plants 50-150 cm. Leaves: basal persistent or caducous; cauline mostly opposite; faces glabrous or sparsely hairy. Paleae puberulent. Ray florets 12-17. Disc florets 35-130. Flowering mid summer-early fall. Fields, roadsides, disturbed areas; 100-900 m; Ala., Ga., Ky., La., Miss., N.C., S.C., Tenn., Va., W.Va. Silphium confertifolium has persistent basal leaves and a diminutive stature that is due to environmental variation; it is best included in S. asteriscus var. latifolium.