I think the *height* of an iris is quite variable, also......it seems to be an ID *tool* that only 'counts' when you grow both iris , together, in the same dirt. It seems (to me, at least) that color intensity, height, PBF, and"speed of increase".....all used as ID tools.......are all quite variable, and dependent on climate ,as well as culture.....in other words, what is 40" tall, and has moderate PBF, and increases fast for me....may, in other gardens, be 32", slow to grow, and increase, and show only a slight tinge of purple.