Mary Ann, changing weather during the time the stalk and buds are developing can really affect how the blooms look. And different blooms on the same stalk can sometimes look different from each other too. Also, I learned the hard way that you should NEVER use Roundup anywhere near irises. They can come out really deformed. And also, mutations can occur at any time that can change the color and look of a flower -- but that doesn't necessarily mean it's a genetic mutation that will occur in the next rhizome and stalk too. I know from growing mini roses that suddenly a branch can produce a different color of flowers, and you can cut the branch off and root it to get a new color for that plant, which they call a "sport". It doesn't affect the original plant, though.
I know my gardeners managed to get too close to my MYSTIQUE with their little wand and Roundup a few weeks ago, and the resulting blooms on the two stalks look so different from MYSTIQUE you would swear it's a totally different plant -- absolutely no ruffling at all, extremely narrow falls, etc. But that plant sticks out a bit from my bed and my gardeners are fairly careless with their little wand, and I'm sure some spray drift hit it -- and it'll probably be all right next year, although I'll move it if I can.
