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Leaf gas exchange, morpho-histological and chemical characteristics were studied in 'Burlat' and 'Summit' sweet cherry (Prunus avium L.) grafted on 'Maxma 14' rootstock. Considerable differences existed between cultivars. 'Summit' had higher leaf mass per unit area and total lamina thickness, principally due to thicker spongy parenchyma. However, 'Burlat' had a higher palisade/spongy tissue ratio and higher stomatal density. 'Summit' leaves had higher concentrations of total chlorophyll and carotenoids, yet 'Burlat' leaves had a significantly higher concentration of total non-structural carbohydrates. Despite the differences in leaf morpho-histological and chemical characteristics, the values for net CO₂ assimilation rate (A), stomatal conductance (g_s) transpiration rate (E), mesophyll conductance (g_m), intercellular CO₂ concentration (C _i) and intrinsic water use efficiency (A/g_s) did not vary between cultivars. Values of A, g_s, C_i and g_m determined in the morning were consistently higher than in the afternoon. Higher decreases for A were measured in 'Summit'. A/g_s increased from morning to afternoon, mainly in 'Summit'. The present study supplies information about the behaviour, at the leaf scale, of the physiological properties of two cherry cultivars in relation to their morpho-anatomical and chemical characteristics. Such information is useful to evaluate the carbon physiology at a whole-canopy scale and to study plant-environment interactions.