The alteration of green spaces resulting from the urbanization process has continued to attract the curiosity of researchers. It is in this perspective that this study focused on the knowledge of the flora characteristic of green spaces in the city of Bujumbura (Burundi). The results revealed that it consists of 127 species belonging to 109 genera and 53 families. The families Euphorbiaceae (7.1%), Fabaceae (7.1%), Fabaceae (7.1%), Arecaceae (6.3%), Poaceae (5.5%), Araceae (3.9%) and Malvaceae (3.9%) are the most represented and alone account for more than a third (33.9%) of the total number of species inventoried. They are mainly dominated by introduced species up to 74.0%. Two species (Lantana camara and Spathodea campanulata) are qualified as invasive. It is necessary to take measures to conserve urban biodiversity in order to avoid the homogenization of urban vegetation in favor of introduced species.