A floristic survey of Lauderdale County, Mississippi was undertaken from the spring of 2004 through the fall of 2009 in order to document the flora and describe plant communities from this poorly studied region within Mississippi. A total of 1175 vascular plant species (1206 taxa altogether, including species and infraspecific taxa) was recorded from the county. Oenothera sinuosa and Geranium molle were collected for the first time in the state of Mississippi, and Carex breviculmis was recorded from North America for the first time. One hundred and eighty-six introduced species were recorded in the county. Forty-seven rare and uncommon species, according to the Mississippi Natural Heritage Program special plant tracking and watch lists, were recorded from Lauderdale County and many range extensions and species disjunctions were discovered. We describe nine primary plant communities in the county and discuss the biogeographical importance of the flora of Lauderdale County relative to the rest of the state.

Dot maps are provided to depict the distribution at the county level of the taxa of Caryophyllidae growing outside of cultivation in the six New England states of the northeastern United States. Of the 263 taxa treated (species, subspecies, varieties, and hybrids, but not forms), 261 are mapped based primarily on specimens in major herbaria of Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, and Connecticut, with most data derived from the holdings of the New England Botanical Club Herbarium (nebc). Brief synonymy to account for names used in standard manuals and floras for the area, habitat, chromosome information, and common names are also provided.