Paynes Prairie State Preserve is located in north-central peninsular Florida, south of Gainesville, in Alachua County. The plant communities of the basin form a diverse and fluctuating mosaic, and are typical of the freshwater marshes and prairies of north-central Florida. The hammock adjacent to Alachua Sink contains numerous sinkholes, is rich in species, and shows little evidence of human or natural disturbance. A taxonomic study of the vascular flora was conducted on the 5600 ha basin and the 10.4 ha hammock. Collections were made from April 1981 to October 1982 and the names are compiled in an annotated list which contains 422 species (423 taxa) representing 108 families. Range extensions are noted for five species occurring on the basin, and the newly described Forestiera godfreyi is reported from the hammock. The plant communities of the basin are also described with respect to floristics, physiognomy, and length of inundation.