Image, please?

Al

i have a R. Tetstrasperma too. I noticed this dark coloration too. It usually happens after I have watered it, I couldn’t tell you why but it does go away. That’s what your pic looks like too me. Have you recently watered it?

What you're seeing is the result of a somatic mutation, purposely induced chemically or by way of a (color) breaking virus in the later stage of tissue culture and meant to make the plant more winsome than its all green counterparts. Unfortunately, the variegation normally disappears as the plant matures.

Al

I see the same thing on my vining pothos and philodendrons after I water them, and I believe it to be due to soil that retains too much water. This happens even though I make sure to remove all perched water (drain at 45 deg, move pot up and down, and even place on a wicking material to remove as much water as possible). Thoughts?

My plant is in fast draining soil and I do the same as you as far as tilting the pot to remove all excess water. It’s not something that happens all the time and I have several R.Tesrasperma and this particular one is the only one I have noticed that with. It is definetly something with the watering process, just glad it isn’t permanen!

Subtle changes in the plant's chemistry or cultural influences can conspicuously change the way light is reflected from the surface of foliage, even to the degree the entire leaf can appear to have changed color. I won't agree or disagree with the idea that watering habits is having an effect on how light is reflected because I don't know; but, the fact you can detect a color break in a plant well-known to be chemically manipulated during tissue culture in order to achieve that effect is a pretty darn good reason to think the underlying reason for the variegation was an intentional act. Another way to look at it is, had the plant not been treated in its embryonic stages to achieve the appearance of chimeral variegation, you would not have noticed a color break.

Al