The effects of variable climatic conditions on physiological and biological traits were investigated in 2-year-old olive plants (Olea europaea L cvs. Chemlali and Chetoui) grown in pots. The studies were carried out during 2013 and 014growing seasons in three Tunisian different olive growing areas (North, Central and South). Vegetative growth and leaf measurements included chlorophyll fluorescence parameters, stomatal conductance; stomatal density, trichome density and leaf density were investigated. Based on our results, we found considerable genotypic differences between the two cultivars. Chemlali exhibited more tolerance to different climatic conditions, with a higher stomatal and trichome densities in the south of Tunisia. Also, Chemlali leaves revealed lower leaf area and had higher density of foliar tissue. The morphological and structural characteristics of the leaves are in accordance with physiological observations (better stomatal regulation and photosynthetic activity as expressed by the measurement of the maximum quantum yield of PSII (Fv/Fm)) and contribute to the interpretation of why the olive cv. Chemlali is well-adapted to different climate conditions than Chetoui cultivar. Furthermore, from the behavior of Chemlali plants we consider this cultivar very promising for cultivation in arid areas.