Ethnotaxonomy and phenotypic evidence for a zone of high common bean (Phaseolus vulgaris L.) diversity in northeastern Amazonian Peru

Abstract The common bean ( Phaseolus vulgaris L.) is a key crop in the Americas, yet its diversity in the Peruvian Amazon Basin remains poorly documented. We examined geographic and ethnographic patterns in vernacular naming and phenotypic diversity of common beans across three biomes: the inter-Andean Marañón Valley, the Highland Rainforest, and the Amazonian lowlands. Using lexical sources, ethnobotanical interviews, and phenotypic evaluation of seeds, we recorded 152 specific vernacular names and 20 generic terms for P. vulgaris across 26 ethnic groups. Naming categories relied primarily on morphological criteria, complemented by references to origin, growth habit, culinary properties, and historical events. Vernacular name richness and phenotypic diversity exhibited a congruent geographic concentration, with the highest values recorded in the Highland Rainforest biome. These results suggest a geographically continuous zone of high common bean diversity in the northeastern Peruvian Amazon, spanning the inter-Andean Marañón Valley, the Highland Rainforest, and adjacent Amazonian regions. While the observed congruence between vernacular and phenotypic diversity is consistent with historical diversification processes, the present evidence does not establish a historical diversification axis. Linguistic and ethnobotanical evidence thus provide a useful framework for documenting and conserving common bean diversity in this bioculturally dynamic region.