Have you ever come across a bloom in your iris bed that had you looking closer and scratching your head? There are instances, both natural and artificially induced, of iris blooms exhibiting some strange attributes. Here's a few common occurrences that I've seen over the years.
This first shot shows the effect of the herbicide Roundup on irises. The poison doesn't kill the iris plant, but it does distort the blooms for the following season. Colors tend to be washed out and petals not fully formed. This is a mild case seen here.
Some irises are unstable in their coloration. 'Batik', one of the most popular broken-colored irises, is one such. Many irises will throw out swipes of a chimeric color on a petal once in a great while, but 'Batik' does so regularly as part of it's pattern. It has even been known to sport new rhizomes of stable plicata patterned flowers devoid of the color-breaking.
Just as some irises are unstable with their genes for color, some others seem to be unstable with their form. In my previous post about Flatties I mentioned the habit of 'Clematis' to be a typical iris flower - until warm weather sets in and new buds open in a flat form. Well, 'Quail' also shows a flat form but this time on only the last one or two blooms that open - as if it just ran out of some parts after making so many flowers and was left with just falls and extra pieces to work with.
It is not uncommon to see multiple petals on an early bloom, and likewise late blooms sometimes lack all the parts they should have. This shot of a bloom on 'Goldfish' shows a range of petals and petaloids trying to mimic a normal flower, leaving a crazy quilt effect for the eye to try and decipher.
Tho distorting the iris' lovely form, these different expressions in our favorite flower can add a sense of wonder and novelty on the rare occasions when they manifest. With the exception of the Roundup damage, they are naturally occurring phenomena and aren't a sign of a problem with your plants.