What wrong with my Iris plant?

Hi all,
Help! Can anyone tell me what's wrong with this Iris? Checked on line, and can't see anything like this.
Thanks in advance.
Cathryn

I think that's what they call 'pineappling"...Most"experts" think it's caused by weather conditions (sudden cold snaps at the time leaf growth starts). .I aleays get some of it too, but I think it has more to do with the emerging leaf being "trapped' in the "existing" leaf.....seems to always be on plants that have an old , dried out, "leaf stub", remaining on the plant. I think that 'restrains' the new leaf, and causes it to wrinkle up.

Thanks crowrita1, it makes sense! . Still looks odd on the plant.