The high urbanization rate of Istanbul in response to rapid population decreased the size and amount of green spaces. Thereby, every green space types are of vital importance in terms of conservation of urban biodiversity. In this study, it was aimed to compare woody species composition of main green space types consist of artificial and natural sites. Botanical gardens had the highest diversity followed by gardens. Residential areas showed to be important in terms of shrub (52%) and evergreen species (58%), which are mostly exotics (71%). The ratio of the invasive plants in the composition was higher in parks, which contain highway greenings and public gardens. Since the most tree species used in public green areas of Istanbul were mostly same with the species used in European cities, all of the green space categories having varied composition must be considered as interconnected habitat patches in urban planning.