The Wabunsee (Carboniferous: Virgilian) through Sumner (Permian: Leonardian) Groups of Oklahoma preserve a record of terrestrial and nearshore marine environments during glacio-eustatic fluctuations caused by southern hemisphere glaciation. This section, with the Pennsylvanian-Permian Boundary firmly established in the Red Eagle Formation on the basis of conodonts, permitted study of vegetational change across the boundary interval. The palynology of 43 productive samples from five cores in Kay and Osage counties in Oklahoma was investigated. Palynomorphs were assigned to eight morphologic groups that also reflect climate preferences. Four distinct palynofloras are recognized. The three transitions between them in the lower Council Grove, middle Chase and lower Sumner groups are abrupt and, in succession, consistent with an interpretation of increasing seasonality/aridity from latest Pennsylvanian into the Early Permian. None of these floristic transitions align with the conodont-based boundary, or with any lithostratigraphic "group" boundary. These palynological data from Oklahoma are in accord with previous data from Kansas that also demonstrated no palynological shift at the boundary and increased seasonality/aridity through this period. Comparison of the palynofloras from Oklahoma, Kansas, and the boundary interval of the Pennsylvanian-Permian Boundary type section in Aidaralash Creek in Kazakhstan reveals differences in composition that suggest local to regional, including climatically induced, heterogeneities that may present an obstacle to confident palynologically based, global correlations in fully terrestrial sections. (C) 2013 Elsevier B.V. All rights reserved.