Urban green spaces are essential to assuring the quality of life. This study aims to study the diversity of plant communities associated with urban green spaces in southwestern Algeria. Based on data collected from 57 phytoecological surveys with an area of 1 m², plant communities were analyzed using diversity parameters (specific richness, biodiversity indices and similarity) and plant functional traits (life forms, morphological, phytogeographical and dispersal types). 32 species belonging to 31 genera in 13 families have been identified. According to the real spectrum (data based on abundance) of plant functional traits, plant species are mainly geophytes (48.27%) which adopt various dispersal strategies, including barochores (71.55%) and anemochores (17.24%). Phytogeographic analysis revealed the dominance of the cosmopolitan element (41.55%) which is well adapted to the Saharan climate. Agglomerative hierarchical clustering of species based on their abundance by Minitab 17 revealed six groups. This work provides important information that can serve as a basis for the management and conservation of biodiversity in southwestern Algeria.