It suggest's underpainting a big tree with a mixture of burnt sienna/ultramarine blue and a touch of cadmium red. Then painting over this wash with a combination of burnt sienna and phthalocyanine blue which conveys the dark branching.
I added the green horizontal ground plane to make the tree rooted in and of the landscape. After painting this I realized I love the graphic quality of this tree. I have begun to think the larger I paint this subject the more impactful it will be.
It was painted with a freedom of expression that I find quite rewarding. It was painted on Arches watercolor paper which is one of my favorite papers to paint on.