The biodiversity of urban areas is strongly affected by anthropogenic impacts, with implications for ecosystem functions and human well-being. Plant diversity can be variable and exceptionally high across urban areas. This study aimed to determine the drivers of variation in plant species richness across university campuses in Turkey. I compiled published and unpublished floristic data from 33 Turkish university campuses. Explanatory data for each campus was collected, including campus area, campus age, climatic variables (temperature, precipitation) and topography. I investigated drivers of richness patterns for total species, cultured (planted) and endemic species, analysing the data using multiple linear regression. Relative variation importance analysis (RVI) was conducted to test the importance of each variable for all significant regression models. I found that Turkish universities had remarkable plant diversity. Total species richness was driven by campus area while planted species richness was driven by campus age, and endemic species richness was driven by elevation and area. Turkish universities house valuable plant reserves that can be used for educational purposes as well as biodiversity conservation.