Today, we recognize several classes of bearded irises (tall bearded, border bearded, standard dwarf bearded, etc. At the time the American Iris Society was organized, in 1920, these classes didn't exist in any sort of codified form. Hybridizers were actually well out in front of any classification system. In other words, hybridizers were producing what we now call Intermediate Bearded Irises (as one example) long before anyone recognized such a class. As you can imagine, whenever a new class first began to emerge, there was some confusion/disagreement about how to define it. So, in some cases, hybridizers would register an iris under a certain class, but as the class later became more precisely defined, the iris would no longer fit and be moved to another class.
It still goes on today, to a lesser degree. Paul Black is developing a line of what he calls "small flowered tbs". They are registered as Tall Bearded Irises. But, if they catch on, it's possible that AIS will one day recognize a new class called Small Flowered Tall Bearded Irises or (something like that) and Paul Black's current line would be reclassified.
