What a beautiful plant!! And good links.
I learned some years ago how you can easily keep apart the species Disocactus ackermannii from the Disocactus x hybridus 'Ackermannii'.
The species:
The growth/stems on the species is never 3 - angled
Flowers are not campanulate/never shaped like a bell
And the stigma lobes are red.
Most of the times you see white stigma lobes, that rules out the species right then and there.
I have seen red ones some time ago here on ATP, I almost fell off my chair!!! I just can't recall who posted that bloom.
