This post describes the process a little, although the image above starts with a different base image. The above started as a photo of the roots of this years Blue City Diesel plant (legal outdoor recreational marijuana back yard grow). Original base image:
For this particular series of images I am working on I used a layer mask to cover up the gray background (which is a door I was holding the root system up against), I added a previously created alien background that started life as macro photography of sandstone. Here is the combined image that I used to generate the first set of mutated images, and from there I kept mutating: