Ecophysiological and micromorphological characterization of green roof vegetation for urban mitigation

•Green roofs have the potential to mitigate urban climate based on species-specific ecophysiological and morphological leaf traits.•Plants with high CO2 assimilation are more apt to mitigate CO2.•The ozone forming potential is negligible as the species studied are overall low BVOC emitters.•Species with high stomata density and with hairy, waxy and rough leaves have high potentiality to retain particulate.•The evergreen shrubs contribute to the improvement of air quality also during winter.