There are a number of different wisteria species, so unless you know for a fact that your dad got his tree from Japan (or a Japanese source) it is probably either American or Kentucky Wisteria or Chinese Wisteria (the most common species in the U.S.). The American varieties are much smaller than the Asian ones - they don't grow as large and their racemes of flowers are about half the length of those found on the asian varieties. Chinese Wisteria in particular is very robust and is an aggressive grower - it is considered an invasive species in some areas. One way to tell them apart - Chinese Wisteria flowers in the spring while American Wisteria flowers in mid-to-late summer. BTW wisteria seeds are poisonous so don't eat any
As far as care goes, I think they are all somewhat similar. They like damp free-draining soils and can grow in full tropical regions up to about zone 6. They all bud back well on old wood and can be easily propogated versus cuttings. Note that plants grown from seeds take years (if not decades) to flower, so you are always better off getting cuttings for your bonsai.
The plant itself is best displayed while in bloom, and bonsai styles that allow for the racemes to be the focus of the tree are best. Consider styles that emphasize the weeping growth pattern of vines, and plan ahead for where you want the flowers. Flower buds pop from the base of the prior year's growth, so you can trim back to the basal buds of the prior year's growth to emphasize the flowers.
