The slanting style or shakan is an elegant style that espouses the ideals of a tree in a natural, conversational style that depicts the buffeting of the natural elements such as wind and storms. In the natural state, many trees slant and sometimes topple as a result of being unable to withstand strong winds. The shakan is the bonsai way of illustrating this weathering effect.
Sometimes trees will also grow slanted if that is the only way for them to get light. In thick forests, slanting is more common than you might expect. This is why the slanting style is considered a way of conveying the quest for light and space.
When a tree slants, the effects of gravity will be magnified and the soil type as well as the location and amount of water inside the soil will have a bearing on the slant of the tree. The roots will generally grow outwards in the opposite direction of the tree to balance the gravitational forces. Although quite similar to the informal style, the trunk in the slanting style is usually straighter than the informal and bent at a certain degree, usually at 45 degrees. But, not all slanting styles follow the true straight trunk model though.
As the name suggests, the trunk is slanted, usually at a moderately steep angle, mid-way between an upright and a cascade style. The slant will be anywhere from 30 degrees to as much as 75 degrees. The lowest branch is made to point away from the direction of the trunk, lending a visual balance important to the bonsai artist.
Even so, care should be taken to keep the result in balance. Longer branches should be distributed away from the slant, shorter branches in the same direction. Longer roots should be encouraged away from the slant, again for balance. Sometimes artists will create an extreme version of the slanted style, for example in the pic on the left, which is also amenable later on with further training, to transform to a full cascade.
Within the style there are several sub-types, such as dai-shakan and chu-shakan. Each sub-type refers to the direction in which the branches are trained relative to the angle of the trunk. In the chu-shakan style, for example, the branch is trained back toward the trunk. Dai-shakan, by contrast, spreads the branches away from the trunk.
The species most suitable for the slanting style are conifer specie such as White Pine, although this style can look quite okay on other less conventional species. The slanting style is quite easy to achieve by either slanting the pot so that the tree goes slanted, wiring, or limiting the direction of daily light so that the young tree grows slanted towards the light.