MTBs have a specific size for the flower--no more than 3" X3" for size. They are decendents of the wild Iris variegate
which is a natural diploid. The yellow standards & yellow &red falls were the color of the wild plants. The first MTBs were that color as well & some still are. Breeders can leave anything alone of course.
So hybridizers started work. They developed other colors. Not a real wide range as they were all diploids. They some people, notably Ben Hagar wanted other colors so started working on tets, often using I.aphylla. Other colors came, but they had to get the flower down to the proper size (which isn't easy. (see next post)
