When someone characterizes a bonsai as a formal upright or chokkan style tree a vision immediately comes to mind. Most of us see a pine tree with a uniformly straight vertical trunk, nicely tapered from the apex to the beginning of the transition to the root base. The roots fan out, giving a sense of stability.
The first branch, the longest and heaviest, emerges at no more than one third the overall height of the tree, and angles slightly downward, giving a feeling of great age. The second branch, on the opposite side and somewhat higher up the trunk, is slightly less important, but balances the primary and establishes the basis for the progression of branches up the trunk.
The third branch, pointing toward the rear, provides depth. This pattern of alternating branches continues to the apex. As branches diminish in both thickness an length, so too does the distance between them. Yet, each branch manages to maintain its identity as a distinct layer of foliage. The silhouette presented is a soft, asymmetric triangle with a slightly rounded apex.
Of course this style of bonsai is not limited to just pines. If you find the right trunk, many species can be styled into a stunning formal upright bonsai. Juniper, bald cypress, larch, spruce, and cryptomeria come to mind. Deciduous trees can also be trained in this style. Or a formal upright forest can be designed. Finding the right specimen for this style is the most difficult part. Developing the branch structure and styling the tree over time will provide hours of enjoyment, and result in a wonderful bonsai.