Somewhere, on one of the forums....Cubits, HIPS, or ATP....we had a thread going on the "scent" of different iris, and had quite a list going, as I remember. There are several that have a "roor beer", or "cream soda' aroma, as well, of course, as the "grape " scent of the pallidas , the "cat pee' smell of English Charm, and the "fresh washed linen " scent of English Cottage. I darned if I can find it, though
! Also...it may have been in Mike U's E-zine ," Flags", on the HIPS site, there was an article that listed a few.
Anyway, there were (are) several with a pronounced "root beer' aroma, although, I think other "points of identification" make more sense, than scents.