Why Plants Are Variegated
Maybe. At least it’s a plausible explanation from what might be called a reliable source, the scientific journal Evolutionary Ecology.
Here’s the summary, with illustration and caption, from the BBC (photographer uncredited, unfortunately):
Short version is they do it to look sick, thus fooling the bugs that might make them sick into thinking they’ve already been drained of vitality.
Words cannot express my investment in this explanation, but if YOU have been expensively seduced (over and over) by some gorgeous variegated thing, only to find when you got it home and put it in the garden that it just looked sick, you will know what I mean.