I think what they did is to let the plant grow big in the ground, then cut the main root to allow the arial roots to grow, then chop the main trunk to allow the growth of small branches and small leaves, I tried to create those a couple of time, but usually they die when I moved them from ground to pot, with or without the cuttings. Some of them survived, ficus and bodhi tree, not the jades, I hardly can grow any jades, not to mention bonsai
