This article presents a research project carried out by the Ministry of Culture, which deals with the self-sown flora of the area adjacent to the river Ilissos. The objective of the project was the rehabilitation and promotion of the grounds surrounding the Byzantine Museum of Athens through planting trees and flowers compatible with the climate, earth and historical memory of the site. The flourishing of most of these vegetal species in these grounds is at-tested by literary sources, travelers’ accounts and Athenian journalists writings, while the existence of other plants, like laurel and myrtle, is presumed on the basis of their mythological role, meaning and symbolism. The comparable study of the inventory of trees and flowers at the end of the article, the additional list of the National Garden flora and the catalogue deriving from Theophrastos’ work On the History of Plants can prove the continuity of the Greek flora from the classical period until now and suggest that some of the plants included in Theophrastos’ History might have thrived in his garden and have sparked the ancient philosopher, the father of Botany, to study them.