Who knows, who uses, and who shares? Social network analysis of the use of a threatened medicinal plant in South Africa

Securidaca longepedunculata is a culturally and medicinally valued plant in southern Africa, yet the social mechanisms shaping its use and knowledge transmission remain unknown. Here, we examined the knowledge-sharing networks of S. longepedunculata in South Africa, drawing on population surveys, structural equation modelling, and social network analysis. First, we found ‘awareness of the plant’ was highest among middle-aged and formally educated individuals, while ‘use patterns’ was strongly gender-based, with early to mid-adulthood men reporting the highest frequency of use, primarily for sexual health purposes. Furthermore, our social network analysis revealed that knowledge transmission operates predominantly through homophilous peer networks, especially among friends and community members. However, older adults occupied structurally central and influential positions, suggesting elements of prestige-biased transmission, whereby respected or well-connected individuals function as preferred models for learning. Of concern is our finding of limited vertical transmission to younger generations, indicating potential erosion of traditional knowledge with time. More concerning is the frequent harvesting of roots. Together, our findings reveal that the persistence and sustainability of S. longepedunculata are shaped by socially embedded learning dynamics. As such, integrating insights from social learning theory into community-based conservation strategies may enhance both cultural continuity and sustainable management of the plant.