I have a large, beautiful Christmas cactus which is...2-3 times a year...covered with blooms that start out as white buds, then open as white flowers with fuscia stamens, and then become pinkish as they age. It has never shown any signs of stress in accomplishing this feat.
However, it apparently did do something mysterious...or else a joke was played on me:
Originally, I had a good-sized scarlet one which had blown over in a strong wind, snapping off numerous pieces and effectively demolishing the plant. So I started again, rooting the stems in water (did you know you could ?). When I had a nice one, branched and healthy with good roots, I thought I'd give it an extra healthy start by potting it up in "soil" that I got from my house's gutter...kept because it looked so rich and black and full of possibility; (but after a while I realized it was composed of nothing but roofing granules and silt). It did ok, but from then on it bloomed white with fuscia stamens, and turned pinkish within a few days; ...Huh ? How could this be ? So I transplanted it back into real soil, but it has remained the same.
Still... I love it, and it's really beautiful...prettier than the ("original ?") scarlet, I think. I have shared pieces with many friends, and they love it too.
What say you ? Did someone switch my original scarlet one ? Does a white-with-fuscia- stamens one exist ? Or did my weird soil somehow permanently change the genes of this plant ?
You will have to ask someone who knows more about how pH of soil can affect flower color as I imagine it could. No genetics changed I am sure, but perhaps also you had a grafted plant and now you have rooted the original base of the plant... no idea really.