Leaf mass per area (LMA) is an important variable in a set of coordinated leaf traits to determine plant species' ecological strategies. We hypothesized that LMA was the main predictor of the adaptive strategies of Sesleria juncifolia and S. nitida (Poaceae), growing on Mount Terminillo (Central Apennines) and cultivated ex situ. We broke LMA down into leaf anatomical components (i.e. leaf tissue density and thickness) and then related them to physiological traits. We found that the different habitats of the two species determine a different control of the anatomical components of the LMA variation. These differences are related to photosynthetic capacity, scaling linearly with leaf biomass investment per unit leaf area. On the whole, our study, taking into account the changes in LMA and its anatomical components, provides a trait framework which could be used to analyze adaptive strategies of other species in dry, mountain grasslands.