Variegation in vanilla
 

What causes the the variegated leaves to turn all yellow instead of the yellow and green variegation. Is it cultural, environmental, or is it both or none? The vine has ‘normal’ variegation on the one leaf (lower left arrow) and all yellow, no green variegation on the next leaf (upper right arrow) and all leaves after that point. The vine goes over the other vine (red arrow). Hopefully you can follow the vine in photo. Is this caused by factors such as light, nutrition, or temperature or is this just the plant doing what it wants? Can the leaves that are all yellow turn back to ‘normal’ variegation over time. Or is this something that will not change?

Some variegated plants, like this, are chimeras. Chimeras are a mosaic of 2 tissue types, in this case one tissue type has normal green chloroplast development and the other does not. In many cases they will persist for long periods of time as a mixture of cells in each growing meristem, so nearly every leaf and segment of stem gets some mixture of green and non-green tissue.

Sometimes one tissue type or the other randomly drops out and you get a nearly or completely green or non-green shoot. Sometimes the apparently missing tissue type will still be there, buried inside the stem where you can't see it. Then it may re-emerge at any time. But if one tissue type is completely missing in a new growth it will probably never revert to the variegated pattern.

If you get a completely non-green shoot it will persist for a while as the rest of the plant supplies it with energy from photosynthesis, but sooner or later it will usually stop growing.

It isn't cultural or environmental, more like a roll of the dice, though sometimes a period of particularly fast growth will change the odds and make it happen more frequently.

Thank you PaphMadMan, your info makes it clearer. That vine is still going strong, has eight+ leaves that way now.

Ray, thanks for the article, very informative. Continues the idea, that PaphMadMan startedof different layers of cell tissue can have different out comes. I think in the article they called it atypical cell division in the meristem that causes a change in the phenotype. Very good article on verigation, thanks again Ray