Onc. Sherry Baby mutation ?
 

Have had this plant for five or so years. Has been a reliable grower and bloomer for all that time. With the red with white lip, and very fragrant flowers this is one of our favorites. As it is finishing it’s blooming cycle this year, the last two spikes to flower seem to be different. The plant is a large one, in a two gallon pot, it had about ten blooming spikes this year. All look the same, that dark mahogany red with white lip (first photo). But the last two spikes to bloom, both of the spikes come from the same pseudobulb. The blooms are different, no white lip. The whole flower is that lovely dark mahogany red color (second photo). We have been waiting to see if the white will show up later as the bloom matures. The lip color has faded slightly, but doesn’t look like the rest of the blooms from this year.

My question is: is this caused by outside factors (environment, cultural practices) or is this a morph/mutation caused by something else (virus, genome problem)?

We have tagged the pseudobulb and will see if this was just a one time freak thing or if this color trait will continue to carry on next time it blooms.
In the hosta world, they would call this a ‘sport’ and if the trait carried over to the next season and on. You would have a new variety. I don’t known if orchids do this kind vegetative propagation. In hosta this is usually caused by some kind of environmental stress that allows a viruses to inter causing the new plant to be different than the parent plant.

In my experience, light levels and temperature can affect that.

Looks mighty nice, though.

PS: It's Sharry Baby, with an "a'.

Yup - what Ray said - I had this happen to mine. It actually had one spike bloom with the expected coloring, and another spike that started a bit later, and so the buds developed in lower temps (mine was growing outside), and had the solid colored flowers.

Thanks for the information

However it happened, I do think it is very pretty. It will be interesting to see what happens with future blooms.