Peperomia is a large pantropical genus of more than 1000 species. The genus is represented by 25 species in Hawaii, of which 22 are endemic. A previous study of Hawaiian Peperomia hypothesized that the present distribution of species is the result of three or four independent colonization events to the archipelago. Many morphological characters used for delineation of the species are quantitative, and therefore it has been difficult to determine relationships among Peperomia species based solely upon the morphology. Nucleotide sequence data from the nuclear ribosomal ITS and 5S-NTS loci were obtained from Hawaiian Peperomia as well as from several Pacific and South America species. Cladistic analyses of the molecular data indicate that: (1) the Hawaiian Peperomia are of pacific ancestry and originally colonized the older northwestern islands, and (2) the Hawaiian species form a monophyletic group. Species relationships are still not well resolved among the Hawaiian Peperomia, which may be the result of past and present hybridization events. However, this study was able to resolve some general patterns, but further research incorporating more variable molecular data will be required to completely resolve the phylogenetic relationships among the Hawaiian taxa.

Key words: biogeography, Hawaiian islands, hybridization, molecular, Peperomia, systematics