Criteria for National Collection Gardens:The purpose of a national collection garden is to preserve a group of Iris, alive for posterity. The value of a particular group of Iris may not be understood at present but once lost it is too late to discover later.AIS National Collections are of two types; Putative National Collections, (listing), and recognized National Collections(listing). The first, is formed as a stepping stone to becoming a national collection recognized by the American Public Gardens Association. The second is a garden recognized by the APGA as a national collection as is following all of their rules and procedures.APGA rules include an Excel spreadsheet listing all cultivars or botanical taxa with fields denoting their provenance, location in the garden, and condition. National collections should also include a legal agreement as to the disposition of the collection in the case of death or disability of the owner, to ensure the plants are not lost but transferred to a new collection holder.National Collections put preservation of the plants first. They may also be display gardens and would follow those rules but are not required to be display gardens and accessible to the public.
-- BobPries - 2013-12-03