Mediterranean ecosystems are among the most vulnerable to climate change, which is expected to increase the frequency and intensity of heat waves and prolonged drought events. These environmental stressors impose strong constraints on plant growth by limiting photosynthetic performance. In this study, we compared leaf functional traits and photosynthetic performance of species widely distributed in the Mediterranean maquis of southern Italy, to assess how the coordination between structure and function supports their ecological resilience during summer. Sclerophyllous Pistacia lentiscus, Phillyrea angustifolia, Quercus ilex and the semi-deciduous species Cistus incanus show contrasting drought-response strategies in Mediterranean summer conditions. Sclerophylls maintain higher photosynthetic rates and water-use efficiency (WUE), supported by stronger stomatal control and more conservative, structurally robust leaves with higher leaf mass and tissue density and lower water content. In contrast, Cistus incanus displays lower photosynthesis, WUE and C:N ratio, reflecting a more resource-acquisitive strategy.

These structural differences reflect distinct patterns of photosynthetic energy allocation. Sclerophyllous species directed a greater proportion of absorbed light toward photochemical processes (higher photosystem activity), thereby maximizing carbon gain under summer drought. In contrast, semi-deciduous species relied more strongly on photoprotective mechanisms, dissipating excess excitation energy through non-photochemical quenching avoiding photoinhibition. This flexible balance between energy utilization and energy dissipation represents two contrasting but equally successful strategies of photosynthetic regulation. Overall, the coordinated adjustments in leaf structure and function explain the ecological success of Mediterranean species and their potential resilience across Mediterranean region.