Relationships within the Caryophyllaceae have never been examined explicitly using phylogenetic methods, despite the central position and well-defined nature of the family in the order Caryophyllales among the eudicots. Within Caryophyllaceae, the Hawaiian Alsinoideae are an important model system for studying the insular adaptive shift in breeding system from hermaphroditism to dimorphic breeding systems. The relationships of the Hawaiian genera of subfam. Alsinoideae Schiedea and Alsinidendron to the rest of the family and relationships within the subfam. Alsinoideae are poorly known. Previous studies suggested that the native Hawaiian Alsinoideae are strongly supported as monophyletic and the result of a single ancestral colonization to the archipelago. These studies suggested that western North American members of the genus Minuartia are sister to the Hawaiian clade, based on the shared presence of similar, unique, nectary projections. Additionally, the monophyly and relationships of the three main subfamilies, (Paronychoideae, Caryophylloideae and Alsinoideae) are in question. The current classification of the subfam. Alsinoideae has been based largely on potentially highly labile characters, such as type of locule dehiscence and number of styles relative to number of capsule teeth; i.e. characters which may be homoplastic. A molecular phylogenetic analysis using matK and trnL C-F sequences reveal that: (1) the closest relatives of the Hawaiian Alsinoideae are a pair of monotypic, circumboreal genera, Honckenya and Wilhelmsia, (2) the subfamilies as currently delimited are not natural groups; (3) the species-rich alsinoid genera Arenaria and Minuartia are not natural groups and will likely require nomenclatural reorganization to better reflect phylogenetic relationships.

Key words: biogeography, Caryophyllaceae, Hawaiian islands, Honckenya, Schiedea, Wilhelmsia