Degas Dancer is a plicata. Hopefully, someone else will come along and explain this far more accurately that I can. When talking about color patterns, bearded iris can be separated into two groups: plicatas (plus some patterns derived from plicata breeding like luminatas and glaciatas) and everything else.
Plicatas typically have petals with a white, or at least light colored, ground with a darker color dotted, stippled, or stitched around the edges. Rare Treat is a very traditional looking plicata. You can see how it looks almost like someone stitched the color onto the falls.
However, the variations are almost endless. In some varieties, the dark markings are so heavy that you can barely see the ground color and it almost looks like a self (like Circle Of Light pictured below).
It is possible for a plicata to have white, or nearly so, standards and plicata markings on the falls. Degas Dancer is an example of that. Some varieties have no markings at all (Clear Choice pictured below). These are often called glaciatas.
"Emma Cook" iris are not derived from plicata breeding. Instead, they were developed from traditional amoena breeding.The genes that create plicata markings are completely different than the genes that create rim of color on an iris like Brilliant Idea. If you look closely at Brilliant Idea, you'll notice that the blue rim on the falls doesn't have that "stitched on" look that you typically see in a plicata.
It's often hard to draw the line between amoena and Emma Cook patterns. Queen's Circle is a classic Emma Cook. Passion And Purity is a traditional amoena, but what about Stage Presence?
Queen's Circle
Passion And Purity
Stage Presence
