You don't see geranium bonsai very often. This originally was a thirty-year old hanging plant. Two years ago, I transplanted it into a  bonsai pot, but the two distinct trunks bothered me. Last week I split into two trees.

Don't know what culitvar this is. However, it is the age not the variety that has provided thick trunks. Typically this trunk is very thin. In fact, these were originally hanging style that flowed over the edges of the pot because the trunk is too weak to do anything else.