Revised description, systematic affinities, and biogeographic considerations of the Fijian endemic Aristolochia vitiensis (Aristolochiaceae)

The poorly known Aristolochia vitiensis is one of the few species of the genus that inhabits SW Pacific Islands. Here we revisit and complement the description of this Fijian endemic. Our study indicates that the species belongs to the subgenus Aristolochia sect. Diplolobus subsect. Euaristolochia. The trifid apex of the perianth is unique among the species of the subgenus Aristolochia and it indicates the presence of three distinct perianth organs, a trait that very rarely can be observed in anthetic flowers.