One hundred seventy-five samples from the Borden Delta provided a detailed biostratigraphic framework for part of the Lower Mississippian clastic succession in Kentucky and Indiana. The samples indicate the eastern and southern parts of the Borden Delta are correlative with the PC Biozone and CM Biozones of Western Europe respectively; however, biostratigraphical problems arise in the western part of the investigated area (Indiana). The appearance of Lycospora pusilla in the samples from south-central Indiana is important in that it raises questions regarding the level of the Tournaisian–Visean boundary, it suggests floral provincialism in this part of North America during the Lower Mississippian, and it does not correlate with the previously established miospore zone from Western Europe.