After a taxonomic clarification and a review of the ethnobotanical data about kava, an attempt is made to elucidate the origin of this Oceanian plant. For this purpose, an ecogeographical survey of the genetic resources of the plant species Piper methysticum Forst. f. and P. wichmannii C. DC. was conducted throughout the Pacific. Local cultivars were collected from 42 different islands, planted in germplasm collections, and described. One hundred eighteen different kava cultivars were identified through morphological differentiation. High Performance Liquid Chromatography (HPLC) on more than 200 root samples revealed the existence of various chemotypes. Analysis of quantity variation in kavalactone content was carried out by using cluster analysis and multifactorial analysis. Field trials of various cultivars indicated that the chemotype was not related to environmental factors or ontogeny, but to genotype. The lineage of the chemotypes suggested that P. wichmannii was the wild species from which farmers domesticated cultivars of P. methysticum.