frankrichards16 said: when i search for Iris sibirica 'First Frost', i get no hits. If i search for Iris 'First Frost' i get it?
There are a couple of reasons for that.
First, the search engine here works quite a bit differently than perhaps people are used to. Unlike google, it doesn't guess what you are looking for. Rather, it searches for EXACTLY what you put in it and tries to match every term. Consequently, the more terms you put in the narrower the results become, any misspellings will result in no hits, etc. So when you added "sibirica" to the search box, you got no hits for First Frost because "sibirica" is not part of that plant's name.
The reason why "sibirica" is not part of the plant's name is straightforward. The vast majority of Siberian Iris cultivars are not descended only from Iris sibirica, but rather they are hybrids created by crossing several species of irises (Iris sibirica was one of the species but Iris sanguinea actually played a larger role) and thus are properly referred to simply as "Iris", not "Iris sibirica".
Unfortunately, many nurseries (especially those that don't specialize in irises) insist on adding the specific epithet "sibirica" which creates confusion and obscures the true nature of these plants.
Worse yet, the same nurseries usually refer to bearded irises as "Iris germanica". The vast majority of bearded iris cultivars are also hybrids derived from several species including Iris pallida, Iris variegata, and Iris aphylla, among others. Iris x germanica itself is believed to be a naturally occuring sterile hybrid that played no role in the creation of modern bearded iris cultivars. Siberian irises can at least trace some of their ancestry to Iris sibirica.