Schefflera arboricola is one of the most suitable species for indoor bonsai growers. It tolerates low light and the errors of beginners in growing bonsai. It can also be grown in the most styles imaginable.
Roots are large and sturdy and can be used to form great bonsai with exposed roots.
My good friend David Fukumoto of Fuku-Bonsai has the best selection of amazing Schefflera for sale. See www.fukubonsai.com