Iris Have Changed Color
I had a bunch of yellow irises in my garden. One year, I received some purple and white irises from a friend of mine, so I planted them next to my yellow irises thinking the color contrast would be nice. The following season, I noticed that several of my irises had become purple and yellow. What caused this?
Hybridizing and sporting (mutation) are two ways iris can change color. The first occurs when two different plants cross. The pollen of one iris pollinates and fertilizes the other resulting in a recombination of genetic material. The offspring take on various or unique characteristics from the parents. This takes several years to occur. First both parent plants must reach maturity and flower. Then pollination, fertilization and successful seed formation has to happen. The ripe seeds then fall to the ground, germinate and may take several years to grow into a flowering plant. Your iris probably sported or reverted. A sport is a mutation. These often result in unique colors or sizes of plants and flowers. They seem to occur overnight. Or your yellow iris may have been a sport of a purple and yellow iris. In this case the sport reverted back to its original color. The last possibility is some of the yellow iris died while the purple increased giving the appearance you’re your yellow iris turned purple. You can remove those you don't like or enjoy the change.