Abstract
BACKGROUND: Hybrid knowledge systems are central to community negotiations of environmental, social, and epistemic pressures. In multilingual borderland areas, interactions between local ecological knowledge (LEK), formal, and popular knowledge systems remain underexplored, despite their importance for the persistence and transformation of medicinal plant use today. METHODS: We conducted 67 semi-structured interviews and participant observation in 21 rural settlements of the Vilnius region (Lithuania), an area bordering Belarus, focusing on the two largest local groups, Lithuanians (LT) and Poles (PL). Detailed Use Reports (n = 1446) on medicinal plant use were coded by the origin of knowledge, classified as local, formal, or popular, and the degree of hybridisation was quantified using the Shannon-Wiener diversity index and hybridisation metrics. Sociodemographic variables (age, gender, education, and multilingualism) were tested for associations with hybridisation using Spearman's ρ and Student's t-tests. RESULTS: A total of 139 medicinal taxa were recorded, of which 68 (49%) were shared between the two groups. Overall, recorded medicinal plant knowledge remained primarily grounded in LEK, sustained through intergenerational transmission. Compared with PL, LT interviewees drew on a broader mix of knowledge-origin domains (H' = 0.97 vs 0.52) and combined them more often (HD = 0.195 vs 0.059). In total, 39 taxa showed hybrid use, predominantly in the LT group. Hybridisation was negatively associated with age but positively correlated with the number of listed plants and their reported uses, while multilingualism showed a near-significant positive trend. CONCLUSIONS: The study suggests that medicinal plant knowledge has evolved here through hybridisation, a process whose consequences are context-dependent, offering opportunities for revitalisation but also a risk of displacement. Dialogic exchanges across families, communities, languages, and media expand people's plant repertoire and strengthen community adaptive capacity. Yet when these exchanges lead to excessive standardisation, they risk eroding the diversity of local traditions. Ethnobotanical research must therefore go beyond documenting popular and formal knowledge sources to interrogate how linguistic and sociopolitical contexts condition the emergence of hybrid knowledge systems, privileging certain forms while rendering others transformed or marginalised.