Beyond the basic styles of chokkan (formal upright), shakan (informal upright), kengai (cascade) and so forth there are several that don’t fit neatly into those categories. The divisions are arbitrary to an extent, but like any specialty they evolve over time to help bonsai artists guide and discuss their work.
Some of the more common advanced styles are the Fukinagashi (Windswept), the Bankan (Twisted) and the Bunjin (Literati).
Like most bonsai trees, the windswept style attempts to emulate nature’s effects in miniature.
Its trunk is slanted, as if grown in an environment where the wind tends to blow more strongly in one direction than another. The branches, too, will acquire a preferred direction as a result of growth that is constantly bent.
Areas near cliffs or hills, for example, do this frequently. Coastal regions often experience the conditions that produce fukinagashi. Meandering rivers, although not the result of winds, are formed by similar basic physical forces.
Unfortunately, emulating forceful winds is beyond the technical means of most bonsai artists. But the style is formed by use of similar forces, even when the artist isn’t aware of why they are basically the same.
Stressing a living plant in a preferred direction causes them to cooperate and tend to grow in that way. Those stresses (physical stresses, not the sort of chemical stress induced by unhealthy conditions) can be achieved by well-practiced means, developed over centuries.
Just as a kengai (cascade) can be formed in part by harnessing the trunk with a cord tied to a stake, so too can the fukinagashi or windswept. Wire can be used as a supplement, but this is more often used for branches than the basic trunk shape.
Often the foliage is sparse, since in natural conditions much of it would have been blown away by the strong winds that produce the bent effect.
The bankan style is thought to have originated in China with the beginnings of penjing, the Chinese art that led to bonsai in Japan.
As the name suggests the trunks are twisted and gnarled, sometimes to the extent of forming animal shapes. The dragon is a popular model for the bankan.
Sub-styles range from the Nejikan, in which the trunk makes only a partial turn to the Takzukuri, or Octopus. In the latter, the trunk is considerably twisted and the branches follow suit, making a kind of vortex shape that emulates the winds that shaped the full-sized species in nature.
One of the most popular bonsai styles is the bunjin or literati. The simple style, with a thin, slanted trunk and few branches is deceptively difficult. It was inspired by Chinese paintings that depicted trees growing in harsh climates. The results are often spare but dramatic.
As the trunk frequently twists around, branches are displayed at sharp angles upward and the tree presents a different view from every side. Japanese Red Pines are a popular species for this style, but there are many others. Branches often twist as they rise.
These advanced styles are not usually attempted by the novice, but sooner or later every bonsai artist will want to try them. They require great skill and patience, but the effort is more than amply rewarded by the beautiful results.