This is a fractal canopy. The pattern is generated as a tree, in which each branch splits into two at a fixed angle. The ratio of the length of the new branch and the old one is also fixed.
By tweaking the branching angle, we can generate patterns such as the H-tree. Here, the new and old branches are perpendicular, and are scaled down by a factor of 1/√2.
Many structures in nature resemble fractal canopies, such as systems of blood vessels or bronchioles in a lung. Lichtenberg figures are a closely related class of fractals which are observed during electrical breakdown, for instance lightning. Another related class are Brownian trees, which are seen during certain types of random walks where particles are allowed to aggregate together.