This study examines the adaptation and evolution of the Hawaiian ethnopharmacopoeia looking specifically at the inclusion of recently introduced plants in the pharmacopoeia as recorded within ethnobotanical studies from 1838–2002. Generally, the number of native plants (both indigenous and endemic) recorded in ethnobotanical studies decreases over time, while the number of recently introduced plant increases. This study lists the recently introduced plants, the date they were first recorded as part of the ethnopharmacopoeia, and their place of origin. It also discusses some of the possible factors influencing the inclusion of new plants in the Hawaiian medical tradition, building on and adding to the current work on the origin of Polynesian herbal medicine.