I have recently got into cacti and succulents alongside my small slipper collection and a discussion there got me thinking - isn't the grex system a flawed one with seed raised orchids such as slippers? My thinking is that a grex such as Saint Swithin can have plants that are F1 crosses (Roth x philippense) and then any subsequent generational selfing or Saint Swithin X Saint Swithin cross. This means that anything beyond an F1 primary cross could have a genetic make up anywhere between a theoretical 100%:0% or 0%:100% of the parent species. This means a Saint Swithin could look like any subsequent backcrosses to the parent species and giving them a separate grex name seems a little pointless, especially if they are then propagated by selfing or sibling crosses. Wouldn't it make more sense to start putting these together as seed strain groups? So all plants that are just Roth x philippense would be Saint Swithin Group and could then have a cultivar epithet if so desired afterwards. Once a third species is mixed in it would need a different group name. I think system would much more accurately reflect the variability of slipper crosses as well as taking out some frankly pretty pointless grex names! I hope that makes sense and would be interested in hearing your thoughts.