Within the diverse (>2,000 species) and morphologically disparate lineage Justicieae, "justicioids" (i.e., members of Justicia and related genera in both the New and Old Worlds) are monophyletic. These plants share a number of morphological traits (e.g., rugulate corollas) such that this result is not unexpected. Our earlier results, however, unexpectedly show that the highly apomorphic Diclipterinae are also part of this group. As traditionally defined, Diclipterinae lack the morphological traits that link "justicioids" and thus have not previously been associated with them. Further, Diclipterinae are sister to New World "justicioids," and this last group is monophyletic. Old World "justicioids" are apparently not monophyletic; most are placed as a series of lineages basal to New World "justicioids" + Diclipterinae; but others are more closely related to Diclipterinae than to other "justicioids." We here test these hypotheses of relationships using substantially expanded taxon sampling and the addition of sequences from the chloroplast trnT-trnL spacer. Specifically, we test (1) the hypothesis that New World "justicioids" are monophyletic by adding representatives of all infrageneric taxa of Justicia and (2) the idea that OW "justicioids" are not monophyletic, again by substantially increasing our sample of infrageneric taxa of Justicia and related genera. This last permits us to identify the "justicioids" that are most closely related to Diclipterinae and to explore the morphological and cytological evidence for this relationship. Finally, we identify monophyletic sublineages of "justicioids," with an emphasis on Old World plants.

Key words: ", Acanthaceae, Diclipterinae, Justicia, Justicieae, Justicioids, Phylogenetics