Öz Taxonomy of the members of section Persicaria (Torn.) L. involved collection and analyses of specimens from 167 sites in 26 States in the eastern and Central United States. A total of 1305 dry specimens were sorted by aspect into 12 different groups. Detailed morphological analyses were conducted on 97 or more specimens in six of these taxa. Eighteen to twenty-two vegetative or floral characters were measured on each specimen. Three different Computer programs (NUTAL, GOCOR, and HYBEX) were used to analyze the data. The results of the morphological analyses did not indicate evindence of introgressive hybridization between any taxa.