A number of months ago, I was at the computer and glanced over to see what I thought was a weed coming up out of the sphagnum moss at the base of an orchid. Upon closer inspection, though, it turned out to be a citrus plant. I must have been eating a citrus - a mandarin of some sort, most likely - at the computer and dropped a seed into the container.
So, if anyone is curious as to what a citrus would look like if grown in very low light (really, too low even for the orchid) and low-nutrient conditions (sphagnum only; zero fertilizer during the period the citrus was in there). Sorry for the poor focus. I would estimate that the plant is about seven months old at this point. It was just re-potted into the four-inch pot.