Can anyone identify this iris? For over 10 years, it has been blooming in the grass, in a field just outside the garden proper. It blooms at the same time as Iris versicolor (but in a spot slightly dryer and shadier than where versicolor grows). It is about 4 inches tall. The number of plants has not increased or decreased over the years (always about 10 plants/blooms). I might have initially planted it, but have no recollection of doing so. I garden in the Bruce Peninsula in Ontario. Thank you for any help.
The photo was not very good. Here is a more usefull picture.
Here's something of a wild guess from me (as I am pretty bad at ID'ing irises) but maybe Iris setosa var. arctica?