BackgroundThe right floodplain at the Llobregat river delta (Catalonia, NE Iberian Peninsula) constitutes an agricultural periurban area adjacent to Barcelona, which has remained ethnobotanically unexplored until now. This area comprises a very heavily anthropized mosaic of soil uses—urban, industrial, natural, agricultural—including the Agricultural Park of Baix Llobregat. The main aim of this work has been to collect and analyze the ethnoflora of this area in order to fill a gap in the ethnobotanical knowledge in industrialized areas.MethodsThe followed methodology has been based on semi-structured interviews. The obtained data have been qualitatively and quantitatively analyzed and compared with other studies.ResultsData have been gathered from 83 informants. The interviewed informants referred 1965 use reports from 292 taxa, including both non-cultivated and cultivated species, from 85 botanical families. Among those, 451 were referred to medicinal uses, 1247 to food uses and 267 to other uses. In the present study, 779 vernacular names have been reported for 287 taxa. In addition to medicinal and food uses, this study significantly enhances our understanding of some agrosilvopastoral uses of plants, artistic use of plants and insights into folk functional foods. In this regard, we propose a novel quantitative ethnobotany index (the folk functional food index) to assess the relative significance of taxa employed as folk functional foods.ConclusionsThe findings of this study highlight the enduring presence of ethnobotanical knowledge in this periurban agricultural region and underscore the significance of its preservation.