RE: unusual forms in species

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Some thoughts on chimeras,
 
I'm not sure how you could be sure if this photo is of a true chimera, or just something weird happening within the tissues of the individual plant itself.  We have a number of Iris cultivars that do this sort of thing routinely, and they are not chimeras.  A chimera would involve tissue of two genetically distinct individual plants combined into one, but not completely integrated, and some patches of tissue being of one and some of the other, and perhaps some mixed.  Usually this would occur in early embryonic development, but it can happen with intermixing of tissue through a graft as well.  It happens in both plants and animals.  However, other things can cause a similar appearance.  When something happens in some tissue, but not all, perhaps a genetic mutation, that switches on or off or alters some visibly expressed trait, the affect can look similar to a chimer! a, but it doesn't mean it is truly a chimera.  Variegates can pop up this way too, and in uni-sexual organisms we can get gynandromorphs (part male, part female).  Pigment and pattern mutations seems to happen moderately often in Iris, especially in hybrids between species (especially those involving Iris variegata).  Sometimes we get a particular pigment present in one part, but not another (such as this one), sometimes broken patterns, and sometimes other weird color patterns.  We also get sports, where part of a plant starts to produce foliage or flowers with different characteristics than the rest of the plant (often involving coloration).
 
I suspect that the plant in the photo has some instability affecting the production of yellow pigments in the flowers, and that each flower might look different, with pattern distribed in varying broken patches.  It could be that part of the plant has lost o! r gained the capability of producing the yellow pigments in th! e flower, and this particular flower got caught right at the dividing line between tissues.  Regardless, I suspect that it is not a true chimera (though it could be).  I doubt a true chimera would have everything so perfectly matched in the different parts (size, shape, pattern, etc.), with only the lack or presence of yellow pigment affected.
 
Dave