The University of South Florida Ecological Research Area (USF Eco Area), located in west central Hillsborough County, is an approximately 306 hectare (756 acre) natural area on the Hillsborough River composed of twelve plant communities. While surrounded on three sides by urbanization, the USF Eco Area makes up the western most section of an extended natural corridor that runs approximately 88 kilometers (55 miles) east and north along the Hillsborough River. An inventory of the vascular flora and the associated ecological communities was developed to better assess the USF Eco Area for educational and research purposes as well as enhance informed decisions when evaluating its status for conservation and management purposes. The study, conducted from June 2001 through August 2005, documented 404 vascular plant taxa in 251 genera and 102 families. Three hundred and seventy-eight taxa (94%) are native to Florida of which 13 are endemic; nine are listed as endangered, threatened, or commercially exploited; four are first time recorded occurrences for Hillsborough County; and ten taxa are listed as Florida Exotic Pest Plant Council’s Category I or II invasive species. Eleven natural plant communities and one ruderal/developed plant community were documented, mapped and characterized by their unique vegetative, topographic, soil, and hydrological components based on qualitative field observations. The blackwater stream, floodplain swamp, floodplain forest, floodplain marsh, hydric hammock, seepage slope, and wet flatwoods are wetland plant communities that cover 65% of the USF Eco Area. Upland plant communities, covering the remaining 35%, are mesic flatwoods, scrubby flatwoods, sandhill, xeric hammock, and ruderal/developed.