The Genus Silphium in Ohio

Abstract

The genus Silphium is represented in Ohio by four species, S. perfoliatum L., S. trifoliatum L., S. laciniatum L., and S. terebinthinaceum Jacqs. Two of these species, S. laciniatum and S. terebinthinaceum, have hybridized in a prairie habitat west of Marion, Ohio. This population has been analyzed using the Gay Method of population analysis. In contrast to a similar population of hybridizing individuals from Coles County, Illinois, where backcrossing is apparently in the direction of S. laciniatum, backcrossing in the Marion, Ohio, population appears to be in the direction of S. terebinthinaceum.