Janet Price wrote:

I have a variety of iris at home and this year three plants have odd
blooms on them I've never seen before. I don't know if they're just
blooming for the first time or if they're defective or virus or the
result of some accidental cross. Both petals and sepals are narrow and
it's bearded.

A photo is at http://www.amherst.edu/~jkprice/yaws/odd-iris.gif

Looks like Blue-Flag from here. Let the seed pods form, and if they
hang down intead of upright like 'normal' iris, then I would be more
certain.

I have a Yellow Flag volunteer that I've admired for about a decade.
I've never touched it and it is now a healthy clump about 4 feet in
diameter.

-snip-
Should I just rip it out now so it doesn't spread?

Why would you do that? Even if it is some freaky new breed of Iris,
it sure doesn't hurt anything-- and I for one think it is pretty.

Jim