whorled rosinweed, Silphium trifoliatum

This rosinweed is sometimes lumped together with S. asteriscus. Or the plants can be separated because of the whorled leaves and smooth stems and bracts. With Silphium, the ray flowers are fertile and the center flowers are sterile. The very similar looking sunflowers are the reverse, with sterile ray flowers. Apparently both genera have found some advantage to their arrangement. Whorled rosinweed grows in AL, DE, GA, IL(E), IN, KY, LA, MD, MS, NC, NJ, NY, OH, PA, SC, TN, VA, and WV. Fayette Co KY, 7/15/15. Aster family, Asteraceae.