Unravelling patterns and mechanisms of biogeographical transitions is crucial if we are to understand compositional gradients
at large spatial extents, but no studies have thus far examined breakpoints in community composition of freshwater plants across
continents. Using a dataset of almost 500 observations of lake plant community composition from six continents, we examined,
for the first time, if such breakpoints in geographical space exist for freshwater plants and how well a suite of ecological factors
(including climatic and local environmental variables) can explain transitions in community composition from the subtropics
to the poles. Our combination of multivariate regression tree (MRT) analysis and k-means partitioning suggests that the most
abrupt breakpoint exists between temperate to boreal regions on the one hand and freshwater plant communities harbouring
mainly subtropical or Mediterranean assemblages on the other. The spatially structured variation in current climatic conditions
is the most likely candidate for controlling these latitudinal patterns, although one cannot rule out joint effects of eco-evolutionary constraints in the harsher high-latitude environments and post-glacial migration lags after Pleistocene Ice Ages. Overall, our
study supports the foundations of global regionalisation for freshwater plants and anticipates further biogeographical research
on freshwater plant communities once datasets have been harmonised for conducting large-scale spatial analyses.