I found out quite by accident that there is a Historic Iris Preservation Society and that they have a new website. It's a club with member fees which are quite steep, and it's a little disappointing that it's not all avaiable to the public, but they have been generous enough to offer a limited photo gallery for free. Nice pics in the "photos" section in case anyone's interested.

Here is a link that might be useful: HIPS - Historic Irises