A floristic inventory of vascular plants for The Nature Conservancy's Tiger Creek Preserve and Saddle Blanket Scrub Preserve, on the Lake Wales Ridge, Polk County, Florida, was conducted from August 2004 through February 2008. The 2308 combined hectares of the Preserves yielded 553 taxa, of which 54 are non-native, 37 are at or near the southern or northern limits of their ranges in Florida, and 24 are new Polk County records. Fifty-five taxa endemic to Florida were found, of which 27 are restricted to Florida peninsular scrubs or scrub/sandhill ecotonal habitats. Nine of these taxa are restricted to four or fewer counties. Twenty-seven are listed in Florida as endangered, threatened, or of management concern, and 18 are listed federally. Twelve plant communities are characterized: scrub, scrubby flatwoods, sandhill, xeric hammock, mesic flatwoods, wet flatwoods, bayhead, seepage slope, depression marsh, floodplain wetlands, blackwater stream, and ruderal. Descriptions and photographs of the plant communities are provided.