Aridity acts as a strong ecological filter, shaping plant functional strategies in arid and semi-arid regions. Salvadora oleoides Decne. and Salvadora persica L., two dominant mesomorphic facultative halophytes, occur across diverse ecozones of Pakistan, where they are exposed to varying degrees of climatic and edaphic stress. Understanding their adaptive responses along an aridity gradient is critical for predicting species resilience under climate change. We investigated intra- and interspecific variation in growth, physiological, and anatomical traits of Salvadora species collected from ten populations distributed along an aridity gradient, quantified using the De Martonne Aridity Index (IDM). Substantial intraspecific variation was observed in both species across the gradient. Certain populations, such as AL in S. oleoides and SA and MP in S. persica, exhibited enhanced growth performance, greater biomass accumulation, and elevated concentrations of osmoprotectants, including proline, soluble sugars, and free amino acids. Anatomical adaptations also varied markedly across populations in response to aridity. In S. oleoides, populations such as AL and SP exhibited well-developed vascular tissues in both root and stem, alongside increased lamina and midrib thickness-features likely contributing to efficient water conduction and structural support under drought stress. In S. persica, notable anatomical enhancements were observed in the SA and RY populations, characterized by pronounced cortical development, thicker sclerenchymatous layers, and enlarged stomatal dimensions. These traits collectively suggest divergent anatomical strategies between the two species, with S. oleoides favouring vascular robustness and S. persica exhibiting cortical reinforcement and stomatal plasticity to maintain physiological function under arid conditions. Interspecific comparisons revealed that S. persica demonstrated stronger structural adaptations under arid conditions, while S. oleoides exhibited greater physiological plasticity. Correlation analysis revealed significant associations between soil properties and plant traits; for instance, soil electrical conductivity and phosphate levels showed strong influences on biomass and anatomical development. These findings underscore the adaptive plasticity of Salvadora species and highlight their potential for ecological restoration in arid and semi-arid regions.