The cause of reduced leaf-level transpiration under elevated CO₂ remains largely elusive. Here, we assessed stomatal, hydraulic, and morphological adjustments in a long-term experiment on Aleppo pine (Pinus halepensis) seedlings germinated and grown for 22–40 months under elevated (eCO₂; c. 860 ppm) or ambient (aCO₂; c. 410 ppm) CO₂. We assessed if eCO₂-triggered reductions in canopy conductance (g_c) alter the response to soil or atmospheric drought and are reversible or lasting due to anatomical adjustments by exposing eCO₂ seedlings to decreasing [CO₂]. To quantify underlying mechanisms, we analyzed leaf abscisic acid (ABA) level, stomatal and leaf morphology, xylem structure, hydraulic efficiency, and hydraulic safety. Effects of eCO₂ manifested in a strong reduction in leaf-level g_c (–55%) not caused by ABA and not reversible under low CO₂ (c. 200 ppm). Stomatal development and size were unchanged, while stomatal density increased (+18%). An increased vein-to-epidermis distance (+ 65%) suggested a larger leaf resistance to water flow. This was supported by anatomical adjustments of branch xylem having smaller conduits (–8%) and lower conduit lumen fraction (–11%), which resulted in a lower specific conductivity (–19%) and leaf-specific conductivity (–34%). These adaptations to CO₂ did not change stomatal sensitivity to soil or atmospheric drought, consistent with similar xylem safety thresholds. In summary, we found reductions of g_c under elevated CO₂ to be reflected in anatomical adjustments and decreases in hydraulic conductivity. As these water savings were largely annulled by increases in leaf biomass, we do not expect alleviation of drought stress in a high CO₂ atmosphere.