Thanks for your responses.

Both sepals and petals are sort of heavy and stiff. These three stalks
are in the midst of iris that look like this:

http://www.amherst.edu/~jkprice/yaws/bearded-iris.jpg

And I gotta say that I like this one better. Perhaps what I'll do is
mark both kinds and at least separate the odd ones and see what they do
next year.

Janet