You may want to contact HIPS, the Historic Iris Preservation Society. They also have a Facebook page. I posed your question on the Iris Lovers FB page and will let you know if anyone has any ideas.
Renee

Here is a link that might be useful: hips

And here is my guess: iris pallida.

Here is a link that might be useful: Iris pallida

Renee posted this over at the Facebook group, and I felt like being a sleuth tonight. Here is what I have found. The anecdotes written in "Landscapes and Gardens for Historic Buildings" include a list of places where the Gardiners shared the "blue flag"... prominent among these places was cemeteries. Following the relatives down, I find Abigail Gardiner, who married Thomas Mumford. They settled first near Narragansett and then moved to Aquidneck Island (near Newport). They are buried in Island Cemetery (Abigail died in 1784). Near the cemetery is Ballard Park, which has a naturalized area with historical plants that offers "glimpses of Aquidneck Island's 17th century past" and "unusually pristine landscape which has both esthetic and historical value". Guess what is planted there? In Ballard Park, down in the Aspen Grove, and then into the Quarry Meadow, you will find a large stand of naturalized blue flag iris. I would bet money that these arrived with Abigail Gardiner. Perhaps the Friends of Ballard Park could give more details. Here's a link to a page with photos of the iris. Scroll down to "Friday" for the iris photos. Hope that helps! ~Evey =)

Here is a link that might be useful: Roy's World

Another suggestion would be to contact Marta Moret, wife of the current president of Yale University. They are living in the President's House, and she is a Master Gardener. In a recent interview, she called the large garden behind the home "beautiful and stately" and said she plans to leave everything historically accurate. I would think she would be a good person to contact with this question, as perhaps there are still some "blue flags" in the garden there. ~Evey

This post was edited by blissfulgarden on Sat, Apr 27, 13 at 11:54

Hi Evey. Good history sleuthing.
Renee

My word! All you wonderful people. I had posted this querry a few years ago on another forum and got lots of interest and help but no happy conclusion. At that time I contacted the former Yale president's wife but got no answer. Thank you Evey , I shall try again. And Ballard Park is certainly a good place to check out and perhaps get a few rhyzomes . Thanks to all of you . You have re-energized the hunt. I will let you know what comes of this.

Evey and Renee, Ballard Park has a small number of our native iris, Iris versicolor. Yale president garden has none that fit. Both wrote friendly letters. HIPS does not go back to 1635. Research into old paintings show Siberian iris. A study of European iris previous to 1635 netted nothing that matched our description. Eventually The Kew Royal Botanic Garden, UK, gave this info: Siberian Iris were imported into England in the Middle Ages by monks and royals! Mary Gardiner had therefor access to them. Today almost every garden has hybrids of this tough plant. Who has pictures, seeds or plants of the original wild species? I theorize (Sept. 2013) that this is our missing treasure. What do you think?
Marianne

How interesting, Marianne. You have some great investigative skills. I love a good quest. It sounds like it may be the Siberians.
Renee

You can find pictures of the species form of Siberian iris, Iris siberica, on the Species Iris Group of North America (SIGNA) web site: http://www.signa.org/index.pl?Iris-sibirica

I don't know of anyone who sells rhizomes of I. siberica. I do know that SIGNA has a members-only seed sale, and it's possible I. siberica seeds are included in that. Joining is quite inexpensive (an e-membership is only $5 per year).

Here is a link that might be useful: I. siberica pictures on SIGNA site

Jeanrichter. Thank you for this information. I spent all morning inhaling all the SIGNA pages.. I'm now even more convinced that the specie Iris siberica may well be our Gardiner Island blue flag. SIGNA has no seeds available this year of this specie. Perhaps someone reading this forum can still come up with a source for this plant. I'd love a rhizome or two. Seeds are a second choice for I am 88 years old so might not be around for a seed to grow to blooming age. However others at our historical garden will carry on and that is a pleasure too. Thanks again to all of you!

This website listed blue flag iris. I do not know if it is the historic one that you are looking for. It does not hurt to ask these folks for more info.

http://www.ambergategardens.com/shady.html

Thanks for that. It is an interesting site! Lots of different Siberian iris which interest me. " Flag" is a common name used for many types of iris, as I have learned . That is one of the reasons this hunt has been so long and difficult.

I'm new to GardenWeb and loving it already. However, as a nubie I have not been able to figure out how to view the picture that Marianne posted. I'm sure it's simple, but I don't have the patience to figure it out! I am attaching an image of what may be a blue flag iris, i.e., iris versacolor. Anybody know anything about this one. Found it on property in far SW corner of Virginia. Property previously had a log cabin.

Thanks for any info.

Lily Kay,
I've never posted a picture since I do not have a specimen of this mysterious "blue flag". However it must look somewhat like the picture you posted which is of one of our American natives. At this time my hunt has pointed to the original species of Siberian iris as found in the wild in eastern Europe etc.. I'm looking for rhizomes and/or seeds of that wild one to plant next spring. Siberian hybrids are beautiful and very common today. I'm hunting their ancestors.

Marianne, thanks for your reply. But I'm a bit confused. Remember that I am new to all this stuff. How do you know that my iris is not the wild one that you are looking for? It was growing "in the wild" and I'm sure had been there for many years. I'm not meaning to argue with you, but I'm trying to understand.

Also found another iris in mix. Of the 200 or so that i rescued, only about 5 were this type. Would I be correct to assume that the seeds that I got from these irises may be hybrids of this one and the other one? Can you give me advice on getting the seeds to sprout. I read that it can take 2 to 3 years.

That is a lovely picture of a bearded iris! I'm no expert on iris , wild flowers are my love. You can get answers to all your questions by going through the many postings in the iris forum, also you can Google your questions.
The iris I'm looking for was growing in Holland before Mary Gardiner brought it to Saybrook. She left Holland in about 1632. We found no evidence that your American wild iris was grown in Holland at that time and then re-introduced to Saybrook. It was a theory suggested and explored early in our hunt. Good luck to you on your hunt for information.

Marianne, thanks.

There sure is a lot to learn about irises. I hope you find what you are looking for.