The autumn tree painting is part of lesson 4 of the Learn and Master Painting oil painting course that I got. It is a very complete course and if you are learning to paint, want to see how another painter works, or want to get started like me coming from another medium, I recommend it.
Autumn Tree Painting by Christopher Johnson
In Lesson 4, the goal is to paint a believable object(tree with autumn foliage and shadow) and we are practicing varied strokes. In the DVD video, the teacher shows how to make varied strokes and explains how it is better to have varied strokes when painting. She also explains how edges should overlap instead of painting up to a line. It isn't clear in writing, but she shows different examples of good and bad edges so it is so easy to understand.
My problem in this case is that while I do have Burnt Umber, I didn't have Cadmium Orange for the lesson. In fact, I didn't have any orange paint at all so instead of making a trip to the art supply store, I decided to see if I could make an orange like color mixing some of the other paints! I took a simple lesson and made it complicated, but in the end, I had my autumn tree with shadow and it did have autumn colors. When I finally buy Cadmium Orange, I'll make another painting of this lesson.
I decided after finishing the tree that I wanted more than the shadow below the tree. Improvising beyond the lesson, I covered the ground with left over "leaf paint" from my palette.