We planted irises in our garden about 6 or 7 years ago and each year they bloom with increasing veracity, this year being no exception. Up until now they have consistently been one color pattern, this:

For a reason I cannot explain, this year’s crop featured all of the above with a lone exception… one bloom is purple. It’s really quite striking in that the color pattern is clearly an exception to what every plant has produced over the years (we planted no others and given how irises spread via tubors it’s not like a squirrel clandestinely planted one that was retrieved from someone else’s yard) and it is considerably taller than any other iris in our garden. One bloom… my purple swan.