Essentially Species crosses are hybrids involving more than one species. As a classification for the American Iris Society they are a micellaneous category of iris hybrids that do not fit into the other 14 horticultural classifications defined by the AIS. They are called Species Crosses to emphasize that the parentage involves one or more species that introduce new genetic material. Thus Species crosses deviate from the standard classifications and demonstrate new innovations that may conflict with the paradigms set forth in currently accepted classes. Ironically The current other classifications began as species crosses. They were proverbial ugly ducklings that after time became recognized as swans.
The goal in creating the class Species Cross was to recognize these orphans as possibly great garden plants and not to wait until a cretain type became common enough to demand its own recognition as a new horticultural class.
Species cross hybridization can be compared to the steady Incremental Hybridizing creating most cultivars. Steady selection from crosses of siblings, backcrosses, selfs and close cousins has produced phenomenal results refining and improving a category. But if one wants to create something truly new than it is worth attempting to encorporate new genes that provide new characteristics. *
As mentioned above Species Crosses existed long before the category was created. They were the foundation of the other current classes. It is worth taking a look at the affects species have made on the development of the Iris classifications; the progress towards new classifications and the potential for crosses in the future.