When ‘ava is not kava: botanical confusion between Piper methysticum and Piper latifolium in the Society Islands (French Polynesia)

Traditional plant knowledge plays a key role in ensuring the appropriate use of medicinal and culturally important plants. However, safety, effectiveness and transmission of ethnobotanical knowledge may be impacted by botanical confusion, which results from the incorrect identification or substitution of plant species with similar vernacular names, morphology, or uses. In the Pacific region, Piper methysticum , known as ‘ava in Tahitian or kava, is a culturally significant plant used to prepare a traditional beverage with social, medicinal, and ritual functions. Although, confusion between Piper methysticum and other Piperaceae species have been reported across Oceania, there is no data about the extent of this confusion and its underlying causes in French Polynesia. This study aimed to investigate the botanical confusion surrounding ‘ava in this area. Ethnobotanical data were collected on five islands of the Society Islands (Huahine, Moorea, Raiatea, Tahaa, and Tahiti) through a questionnaire-bases survey and a photo-elicitation approach using photographic boards representing different species. Information on plant uses, preparation methods, vernacular nomenclature, and knowledge transmission were collected from 28 participants to explore factors associated with misidentification. Among the 40 plants records provided by participants, only 12.5% corresponded to Piper methysticum , whereas 57.5% were identified as Piper latifolium . The photo-elicitation phase confirmed a significant level of confusion, with more incorrect (36.2%) than correct identification (25.9%). Multiple vernacular names were associated with ‘ava , and identical names were applied to different botanical species. This confusion appears to result from the interaction of several factors, including morphological similarities within Piperaceae, the high variability of Piper methysticum cultivars, ecological availability of substitute species, and historical transformation of ‘ava -related practices. This study provides the first quantitative assessment of botanical confusion surrounding ‘ava in French Polynesia. The findings suggest that such confusion should not be interpreted as a loss of traditional knowledge but rather as a part of a dynamic reconfiguration of ethnobotanical knowledge influenced by cultural, historical, and ecological processes. To better understand the evolution of plant knowledge and its consequences for the usage, more interdisciplinary study combining phylogenetics, phytochemistry, and linguistics will be necessary.