I just got this picture scanned from slide.
It is iris milesii, sown 4-5 years ago, I have aprx. 10 rhizomes of it,
from which I got 3 stems, and blooming for nearly a month.
It is growing on a west faced side of the rock garden in sandy soil, where
there are no standing water. It is good to keep the rhizomes fairly on the dry
side during winter.