The Middle-Late Pennsylvanian transition is marked by major change in coal floras across Tropical Pangea, but changes in the more heterogeneous clastic floras not associated with coals are less clear. To help clarify vegetation patterns through time in the Western Interior Basin, we propose an investigation of the palynology of the Dennis Formation in Missouri from 8–10 sample sites. The Dennis Formation is a unit of early Missourian (early Late Pennsylvanian) age in the midcontinent depositional basin with plant fossils preserved in carbonate mudstones in its upper part. Previous research on the Dennis Formation has focused on the macrofossil diversity, which primarily includes cordaitalean and medullosan foliage. Preliminary analysis of one site shows a dominance of monosaccate grains, with smaller quantities of bisaccate pollen, monolete spores, and trilete spores, which will serve as a guide for identifying grains from other sites The abundance of monosaccate and bisaccate grains (~50%) suggests cordaites and/or conifers were an important part of forest canopies, and the remaining spores capture elements of plant diversity that have not yet been detected among the macrofossils.