What kind of Iris?

I bought some perennials from a local gardener and I know this is an iris but have never seen a flower like this. Any ideas?

 

I think it's a Japanese iris, Iris ensata. Perhaps the flower on yours is a bit old, with the petal edges being curled up.

 

Thanks abgardneer, the petal edges were always curled, the flower was only open for a day or 2 when I took this picture.