<p>Acidic soils are defined by rhizotoxic levels of aluminum and excessive availability of manganese (Mn²⁺), which is toxic to sensitive species. The mechanisms underlying Mn²⁺ tolerance in species adapted to such environments remain poorly understood. <i>Lamium album</i> and <i>Mentha aquatica</i>, two Lamiaceae species native to acidic soils, were propagated under controlled conditions and treated with 2.0 (control), 200, and 800 µM Mn (pH 5.0) for four weeks. Exposure to 200 µM Mn enhanced biomass production, photosynthetic pigments, photochemical performance, nitrogen assimilation, carbohydrate synthesis, and nutrient homeostasis in both species, and improved oxidative stress protection. Growth reduction under 800 µM Mn occurred only in <i>L. album</i>, which also developed marked symptoms, including chlorosis in young leaves and brown lesions in mature leaf lamina corresponding to localized MnIV deposition. In <i>L. album</i>, both constitutive and Mn-induced levels of the cell wall (CW)-bound phenolics, lignin, and callose were significantly lower, whereas antioxidant enzyme activities were higher compared with <i>M. aquatica</i>. The absence of symplastic Mn toxicity symptoms and reduced expression of apoplastic symptoms in <i>M. aquatica</i> was attributed not only to lower foliar Mn accumulation but also to increased deposition of Mn²⁺-binding compounds and enhanced cellular barriers via greater callose accumulation. The findings demonstrate species-specific strategies for Mn toxicity response and underscore the complex interactions between Mn and leaf structural components.</p>