Tree Style Basics
Excerpted from Wikipedia
Styles can be grouped based on different criteria, such as the trunk orientation or the number of trunks in the bonsai specimen. Some of the major style groupings include:
Trunk orientation: The orientation of the bonsai tree's main trunk is frequently used to identify the style of a tree. Different terms are used for a tree with its apex directly over the center of the trunk's entry into the soil (these are the upright styles), slightly to the side of that center, deeply inclined to one side, and inclined below the point at which the trunk of the bonsai enters the soil.
Trunk and bark surface: A number of styles describe the trunk shape and bark finish. For example, a bonsai with a twisted trunk is classified differently than one with a split trunk or hollowed trunk. The deadwood bonsai styles identify trees with prominent dead branches or trunk scarring.
Trunk and root placement: Although most bonsai trees are planted directly into the soil, there are styles describing trees planted on rock. For example, the root-over rock style is a different style from the style in which trees are rooted wholly within (atop or on the sides of) a large rock.
Multiple trunks: While the majority of bonsai specimens feature a single tree, there are well-established style categories for specimens with multiple trunks. Within these styles, a bonsai can be classified by number of trunks alone. The configuration of the trunks can also be described by specific styles, including Raft and Sinuous styles for multiple trees growing from a connected root, and the general term Forest style for multiple unconnected trees in large number.
These terms are not mutually exclusive, and a single bonsai specimen can exhibit more than one style characteristic. When a bonsai specimen falls into multiple style categories, the common practice is to describe it by the dominant or most striking characteristic. For example, an informal upright tree with prominent areas of missing bark and trunk scarring will be described as a Shari style rather than an Informal Upright style. Below you’ll see a catalog of the most common styles.
Summary of Common Styles
Figure 1 - Thanks to BonsaiEmpire.com for use of their images
For more info see http://www.bonsaiempire.com/origin/bonsai-styles