According to the number of trunks
There are mainly five types in this classification. The single trunk, twin trunk, three trunks, five trunks and the clump type where the trunks cluster and grow from one root. For a glance the clump style will look like a group planting style, where each tree will be different and of the same variety.
According to the shape of the roots
There are three groups in this style, exposed root, sinuous root and the raft root style. In exposed root style one will be able to see many roots and the tree has a look of years of endurance of weathering. The sinuous root style gives an appearance as if they have individual roots but they grow from one. Raft root style have multiple trunks are actually branches from a buried trunk and they usually grow instraight line.
According to shape of the branches
These are very interesting shapes that can be seen. The first one is called broom style where the branches resembles a broom turned upside down with the treeâ€™s main trunk standing straight or in an informal slant. There are numerous branches that come out from the main trunk. The windswept style resembles a tree near a sea shore. Here all branches of the tree lean to one direction as if they are driven by strong wind. Another style in this classification is called the extended style. Here a single trunk tree has large branches extending in one direction.
According to composition
There are two main classification in this style, one the group planting style and the other rock grown style. In group planting many trees of the same species, preferably, is planted in one tray. In this there is no restriction as to how many trees can be planted, however if it is less than 7 it makes it look good. This again depends on the size of the tray and the type of tree as well as its size. The tallest and thickest trunk tree can be the main tree of the group and the rest can be arranged in a balanced way. It will be appealing to use unequal intervals while arranging the trees and the main tree off center of the tray. The other style rock grown or on the rock is again an interesting style. Here the tree is planted on a rock and the roots are trained to grow on the rock. Please see my photo.
In maintaining all these styles repotting is an important activity and the bonsai trainers must be clear and acquire experience. The wiring technique, bending, tools used for bonsais and other major aspects I plan to write in near future.