Exemplified by studies of the SE Asian genus Cryptocoryne (Araceae) we provide evidence that: 1) interspecific hybridization is an ever-ongoing process, and introgression and gene exchange takes place whenever physically possible throughout the region; 2) artificial hybridization experiments confirm that wide crosses are possible in a large number of cases; 3) rivers and streams provide numerous, diverse habitats for Cryptocoryne diaspores to settle in; 4) the changes in habitats caused by recurrent glaciations resulting in numerous splitting and merging of populations facilitates hybridization and segregation of subsequent generations; 5) hybridization is a major driving element in speciation; 6) populations are the units and stepping stones in evolution – not the species.