Some believe this is a hybrid of Prairie Dock (Silphium terebinthinaceum) and Compass Plant (Silphium laciniatum). Others feel it is a variety of Prairie Dock as treated by Fernald: Silphium terebinthinaceum var. pinnatifidum. Still others treat it as a distinct species: Silphium pinnatifidum. Online reading seems to indicate further research is necessary. Photographed at Cressmoor Prairie Nature Preserve in Hobart, Indiana on August 14, 2009.