Blackberry Lilies (Iris domestica) have gotten bounced around a lot by taxonomists (witness all of the synonyms listed in the database), but it is currently considered to belong in the genus Iris. In that sense, it's a true iris.
Bonnie is correct that you probably can't cross it to a "regular" iris (bearded, siberian, etc.). However, people have been doing crosses involving Iris domestica, in particular crossing it to Iris dichotoma.
Naturally
, the results of these crosses go by several confusing names: Candy Lily, Pardancanda (combination of Pardanthopsis, the old name for I. dichotoma, and Belamcanda, the old name for Iris domestica), and Iris x norrisii to name at least three.
Iris norrisii is the preferred name at the moment:
http://garden.org/plants/searc...
The AIS blog has an interesting post about them here:
http://theamericanirissociety....
