I was just wondering, but how did someone find out about the U. sandersonii 'Blue'? Was it growing in the wild, or was it a mutation?
Well, hmm... My sandersonii white continues to flower continually, but after only two rather runty flowers (half-sized compared to the white), it appears that my blue has had enough and is quitting again. I am seeing no new scapes appearing. Nothing has changed that I can tell.
I have no idea who discovered (or created) the blue variant, but it is pretty. I wonder what would happen if you crossed the two? Which color would be dominant? Or would you get a surprise?
Or *can* you get seed from these flowers at all? Are they self-fertile, or is intervention necessary? I honestly haven't paid much attention as the white has been off by itself, with no where for potential seeds to spread to, other than a praelonga pot (and there's been no sign of this after 2+ months of continuous flowering).
Maybe you can conduct a controlled experiment by having the two of them side-by-side from spring through fall, outside, and see if the pollinators can cross things for you - assuming it is possible for them to operate that way.