The Japanese have a strong midrib running up the foliage. I don't think the Louisianas do. It is cold and raining so I can't double check right now, lol.
Remy

remy is correct. Also LA foliage is wider.
LA rhizomes are big and tend to be yellow and brown.

Thanks for the tips. I was surprised that I have so many Louisiana iris! Thanks again.... I normally hang out at the daylily forum, but will visit here often!