This study investigates global patterns and determinants of vascular plant diversity. It analyzes the species richness of vascular plants across 1,032 geographic regions worldwide, identifying key environmental and historical factors influencing diversity. The results show that potential evapotranspiration, number of wet days, and topographical and habitat heterogeneity are core predictors of species richness. After accounting for environmental effects, the residual differences across major floristic kingdoms are minor, except for the uniquely diverse Cape Region, highlighting the role of historical contingencies. The Cape Region has more than twice as many species as expected by the global environmental model, confirming its unique flora. A combined multipredictor model explains approximately 70% of the global variation in species richness and fully accounts for the latitudinal gradient in species richness. The models illustrate the geographic interplay of different environmental predictors of species richness. The findings suggest that different hypotheses about the causes of diversity gradients are not mutually exclusive but likely act synergistically, with water-energy dynamics playing a dominant role. The geostatistical approach presented is likely to be useful for identifying richness patterns of other taxa without single-species distribution data. The study highlights the importance of spatial analysis techniques in improving conceptual understanding and quantitative knowledge for conservation of understudied taxa. The results show that environmental factors, such as climate and topography, are major drivers of species richness, and that historical factors can also influence diversity. The Cape Region is an exception, with its unique flora likely due to historical and environmental factors. The study also shows that many regional differences in species richness that have been attributed to historical factors can be predicted by contemporary environmental differences. The findings demonstrate that different hypotheses about the causes of diversity gradients are not mutually exclusive and that environmental and historical factors likely act synergistically. The study provides a geostatistical approach to capture the richness gradients of many less studied groups of organisms. The results confirm that the Cape Region has a unique flora, with more species than expected by the global environmental model. The study also shows that the latitudinal gradient in species richness can be explained by environmental factors, and that the combined multipredictor model is effective in predicting vascular plant diversity across the globe. The study highlights the importance of spatial analysis techniques in understanding and predicting species richness patterns. The findings suggest that environmental and historical factors are important in shaping species richness patterns, and that the Cape Region is an example of a region with a unique flora due to historical and environmental factors. The study also shows that the latitudinal gradient in species richness can be explained by environmental factors, and that the combined multipredictor model is effective in predicting vascular plant diversity across the globe. The study provides a geostatistical approach to capture the richness gradients of many less studied groups of organisms. The results confirm that the Cape Region has a unique flora, with more species than expected by the global environmental model. The study also shows that the latitudinal gradient in species richness can be explained byThis study investigates global patterns and determinants of vascular plant diversity. It analyzes the species richness of vascular plants across 1,032 geographic regions worldwide, identifying key environmental and historical factors influencing diversity. The results show that potential evapotranspiration, number of wet days, and topographical and habitat heterogeneity are core predictors of species richness. After accounting for environmental effects, the residual differences across major floristic kingdoms are minor, except for the uniquely diverse Cape Region, highlighting the role of historical contingencies. The Cape Region has more than twice as many species as expected by the global environmental model, confirming its unique flora. A combined multipredictor model explains approximately 70% of the global variation in species richness and fully accounts for the latitudinal gradient in species richness. The models illustrate the geographic interplay of different environmental predictors of species richness. The findings suggest that different hypotheses about the causes of diversity gradients are not mutually exclusive but likely act synergistically, with water-energy dynamics playing a dominant role. The geostatistical approach presented is likely to be useful for identifying richness patterns of other taxa without single-species distribution data. The study highlights the importance of spatial analysis techniques in improving conceptual understanding and quantitative knowledge for conservation of understudied taxa. The results show that environmental factors, such as climate and topography, are major drivers of species richness, and that historical factors can also influence diversity. The Cape Region is an exception, with its unique flora likely due to historical and environmental factors. The study also shows that many regional differences in species richness that have been attributed to historical factors can be predicted by contemporary environmental differences. The findings demonstrate that different hypotheses about the causes of diversity gradients are not mutually exclusive and that environmental and historical factors likely act synergistically. The study provides a geostatistical approach to capture the richness gradients of many less studied groups of organisms. The results confirm that the Cape Region has a unique flora, with more species than expected by the global environmental model. The study also shows that the latitudinal gradient in species richness can be explained by environmental factors, and that the combined multipredictor model is effective in predicting vascular plant diversity across the globe. The study highlights the importance of spatial analysis techniques in understanding and predicting species richness patterns. The findings suggest that environmental and historical factors are important in shaping species richness patterns, and that the Cape Region is an example of a region with a unique flora due to historical and environmental factors. The study also shows that the latitudinal gradient in species richness can be explained by environmental factors, and that the combined multipredictor model is effective in predicting vascular plant diversity across the globe. The study provides a geostatistical approach to capture the richness gradients of many less studied groups of organisms. The results confirm that the Cape Region has a unique flora, with more species than expected by the global environmental model. The study also shows that the latitudinal gradient in species richness can be explained by