The study of the urban flora of Messina bas brought to 1ight an ecosystem rich in species. Despite the abundance of plants widely distributed and with a short life cyc1e the importance of Mediterranean species has been confirmed. They play a vital part in urban landscape, determing the physiognomy of several areas. The strong ties among the urban flora, the anthropic activity and the climatic conditions of the territory were ascertained. The positive role of the winds for the flow of species from natural ecosystems of the surroundings and for the renewal of the urban flora has been observed.