The tallest iris I have is 'Material Girl', registered at 48 inches. I don't think it has ever gotten quite that tall for me - there is something about my growing conditions that leads to iris growing shorter than their genetic potential. Anyway, it is still pretty tall, is the last iris in my garden to bloom, and has thick substance with the deep markings on the falls that you can see in the photograph. Its stems are strong - I never have to stake it.
