I did this painting recently and made it entirely from my imagination. It went through a bit of trouble, but I liked the way it turned out in the end.
I used real acrylic paints (the ones in tubes) for this, and I loved them! They have such a smooth and lovely finish, so good for blending, and quick drying! They're easy to clean up (unlike oils) and fun to paint with. I may sound a bit over-excited, but I really, really enjoyed painting with acrylics, and I plan to use them in future.
(It may be useful to mention here that I used blue and yellow paint to make green, and to show the darker and lighter areas, I just increased the amount of blue or yellow.)