Phylogenetic analysis of the nr ITS region indicates that several species of the genus Charpentiera, C. autralis of French Polynesia and C. obovata populations of Kaua’i and Moloka’i, have historically hybridized with Achyranthes mutica, endemic to Hawai’i and Kaua’i. Analysis of the plasmid psbA-trnH region suggests that Achyranthes served as the pollen donor and Charpentiera as the seed donor in the hybridization event likely occurring on Kaua’i. Other C. obovata individuals from Maui and Lana’i show no signs of hybridization, indicating separate dispersal events of hybrid and non-hybrid forms to the Maui Nui Complex. Morphological analysis paired with phylogenetic results indicates that non-hybridizing Charpentiera species likely founded moist habitats and radiated to dryer habitats. These results also support founder event speciation of Charpentiera originating on Kaua’i and dispersing to the younger main islands of the Hawaiian archipelago.
