Urbanization shaped assembalages of medicinal plants used to treat diseases in Ghana

Rapid urbanization alters landscapes and medicinal plant availability, yet its influence on the composition, diversity, and cultural importance of medicinal flora across urbanization gradients in West Africa remains poorly understood. This study examined how urbanization shapes medicinal plant assemblages used for disease treatment across an urbanization gradient in Ghana. Between February and September 2024, a mixed-methods approach and multistage stratified sampling were employed to survey 600 long-term residents and key informants from 18 communities (7 rural, 5 peri-urban, and 6 urban). Structured and semi-structured interviews, complemented by guided field walks, were used to identify medicinal plants to species level. Species richness, Shannon diversity (H′), Jaccard similarity, hierarchical cluster analysis (Ward’s linkage), and citation frequency were used to assess diversity, assemblage patterns, and cultural importance. A total of 67 medicinal plant taxa were documented. Urban (53 species; 79.1%) and rural (52 species; 77.6%) communities exhibited similarly high richness, whereas peri-urban communities supported fewer species (35; 52.2%). Twenty-five species (37.3%) occurred across all settlement classes and represented 71.4% of the peri-urban flora. Trees dominated life forms (45–54%), followed by herbs and shrubs, while climbers and grasses were uncommon. Although urban sites recorded the highest mean richness (18.67) and diversity (H′ = 2.65), and peri-urban sites the lowest (13.20; H′ = 2.28), differences were not statistically significant (richness: F = 0.45, p = 0.645; diversity: F = 0.64, p = 0.540). Jaccard similarity indicated moderate overlap among settlement classes (56.9–63.6%). Cluster analysis identified four culturally meaningful assemblages comprising a native tree-rich core, two introduced species-rich market and home-garden groups, and a tree-dominated economic cluster. Introduced species accounted for approximately 58% of the flora. Urbanization restructures medicinal plant systems through cultural selection and management rather than species loss. Conservation strategies should prioritize peri-urban habitats, urban agroforestry, tree retention, and household and market-based interventions to sustain medicinal plant resources and associated traditional knowledge.