The vascular flora of Claridon Prairie, a 2.2 ha prairie remnant prairie in Marion County, Ohio was studied quantitatively during the growing season of 1999. Panicum virgatum had the highest importance value, followed by Solidago canadensis, Silphium terebinthinaceum, Carex species, Spartina pectinata, and Schizachyrium scoparium. A total of 177 species were recorded between 1997 and 2002, consisting of 1 fern ally, 56 monocots and 120 dicots. Of this total, 12 were woody species and 29 introduced exotics, 1 of which was woody. The Floristic Quality Assessment Index (FQAI) for the site is 46.10, indicating sufficient conservatism and richness to be considered significant from a statewide perspective. The flora includes 5 state-listed rare plants.