The Median Iris society worked on the ID of luminatas in the 1960-70 period. those people interested in historic irises can often spot them as they were known as 'fancy'.. The SDBs seem to be hardier than TBs as part of the heritage of those is mountain I. pumila of Europe. Plicatas are a complex series including the pattern that we all recognize as plicata, luminats, glaciates (absence of color & what Chuck Chapman call enhanced anthrocyanin, purple which has the plicata gene in the background. These are dominant as in this photo of SDB 'Black Lightning'.
This explanation is posted as an aide for finding interesting things in your garden.
