Blackland prairies are found in two regions of Mississippi and Alabama, the Black Belt and the Jackson Prairie Belt. As the vegetation of remnant prairies in these belts has received limited attention, we collected and identified the grasses and forbs from 19 sites in Mississippi and western Alabama over a year. A total of 196 species were collected, including 168 native species. When compared with prairie species lists for these regions from the early 20th century, our results suggest that 18 species present then may now be rare or absent. Habitat data for these species indicate that most favor more mesic or sandier soils. Their apparent absence implies that existing prairies are a subset of historic prairies that were not useful for agriculture because of drier and/or more clayey soils. To preserve the biodiversity of this ecosystem, conservation efforts should include more mesic or sandy sites, including prairie-forest ecotones.