Criteria For Species Used as Bonsai: Good Bonsai Potential
Anne Spencer -- Reference: Basic Bonsai Design, by David De Groot, 1995
The plant you select must be able to retain its distinctive treelike features. It must tolerate pruning: Drastic creation pruning, and pinching & trimming.
The roots must adjust to container growth: Produce fine, healthy root growth in a restricted root space.
The plant must tolerate transplanting: Roots must have strength and vigor, and promptly resume growth after transplanting.
It should reduce its rate of growth in a container without adverse effect. Continuing strong growth can lead to bad scars.
If the internode length is short you have a head start. Reduction happens when growth slows.
The leaf size should be within reason. A larger leaf should reduce in size, but starting with a small leaf is best.
Pick plants with naturally small fruits and flowers. It is difficult to change their size.
For material you may use trees, woody plants, dwarf forms (there are some problems with these, as well as good things), non woody plants such as chrysanthemums.
Material may be tropical, semi-hardy, or hardy.