Betty, I greatly appreciate the info. And I love the photos.
There's a spot at the end of my driveway where iris grow and bloom every year without my help. Last year I tried to divide the iris, but could not get the shovel to go into the ground more than about half an inch. So I decided to just leave them alone. Not far away, every other plant I have put there has died including drought tolerant sedums, grasses, wildflowers, and agaves. But iris that I bought on sale for $2.00 a piece seem to be thriving a year later.
Since this is a rose forum, I need to point out that there are lots of spots on my property where there are giant granite boulders six inches below the surface. No rose could grow there. And even though official iris catalogues tell you that you need eighteen inches of good soil, it seems to me that iris thrive in these locations, even on the poorest soil. So ... there is a way in which iris are complementary to roses in their cultural requirements. That's good, because they are usually competitors for attention in the flowering category. Smaller flowered roses such as certain polyanthas can really complement iris, though.