Oenothera

Here are three species of Oenothera. Left to right, we see a yellow O. missouriensis, a white O. pallida, and a pink O. speciosa.

Oenothera generates so many dramatic variants, so frequently (for interesting reasons) that Hugo DeVries coined the word "mutation" when working with it.

We now know that these aren't mutations in the current sense of that word; it was the right idea for the wrong reason.