Essential oil in Betula spp. leaves naturally growing in Estonia

► We investigated the essential oils of leaves of Betula pendula, Betula pubescens, Betula humilis and Betula nana. ► The essential oil composition of B. humilis and B. nana leaves was analysed for the first time. ► The bicyclic sesquiterpenoids were found in all birch species as the main group of compounds. ► B. nana contained less bicyclic sesquiterpenoids and more aliphatic compounds than other birches. ► We conclude that the findings could be used in chemosystematics of birch species.