Anyone Recognize this Iris?

This morning while walking around the garden, I came across an iris I had never seen before. I can't figure out where this iris came from or what kind it is. It does not look like any of our other irises, and it is not located with other irises in our garden. It just appeared, all by itself, in an area that we don't mow, about 10 feet away from a bed of yellow swamp irises. Anybody know what kind of iris this might be? Could it be an offspring from the swamp irises, crossed with some other kind of iris in our garden?

I'm a novice at growing irises and would appreciate any thoughts you might have.