So... I got to googling something about irises and ran across a blurry picture of Iris danfordiae that looked like it might have green striped style arms so I googled for better pictures and found Alan McMurtrie's website featuring his hybrid reticulata irises. I was amazed at the new colorations he's developed, but especially interested in the greenish ones. I e-mailed Alan and he gave me permission to post these pictures of some of his greenish hybrids. If you want to see all of his work -- and there's a whole bunch -- here's his website's URL:
I think that this looks like a more developed form of the coloration, I'm seeing in that one diploid bearded seedling. And from the appearance of Alan's hybrids (and discussion with Alan), it appears to be a blending effect of anthocyanin and carotenoid pigments that gives the visual appearance of green. I just asked (by e-mail) but haven't heard back yet, if Alan might have an idea why, in one iris the blend appears green, yet in another it appears reddish-brown. Is it maybe a patterning difference -- I'm thinking side-by side mosaic patches of yellow and bluish-purple might appear green while overlapped they might appear brownish-red.
In whatever case, these hybrids definitely have inspired and encouraged me to focus more on intensifying this coloration in my bearded lines.
I especially like the bottom right one -- named 'Sea Green'