Relationships of eastern North American Phlox (Polemoniaceae) based on ITSsequence data

Phylogenetic relationships of eastern Phlox (Polemoniaceae) are examined us ing sequence data from the internal transcribed spacer (TTS) region of the nuclear ribosomal DNA. Eastern North American Phlox species have been the f ocus of many evolutionary studies, and hybridization is thought to have Fla yed a role in the origin and evolution of some taxa. The phylogenetic infor mation presented here leads to several important conclusions relevant to ta xonomy, notably that Wherry's sections Phlox and Annuae are not mono-phylet ic, and that the eastern mat-forming taxa and the annuals of central Texas each form monophyletic groups. Neither of the two large species complexes i n the east the P. pilosa complex and the P. glaberrima complex, is monophyl etic in the ITS tree. While the tree is consistent with a history of hybrid ization, the ITS data do not directly support previous hypotheses of hybrid origin of particular taxa.