According to Greg Green in his book "The Cannabis Breeder's Bible" this is called auto-topping, a mutation caused by chromosome modification. This is not a common mutation so it's probably rarely seen. I will start some clones to determine whether this passes on to them or was the mutation...
This is a "self-topped" plant. No training or pruning was done to get multiple colas and numerous side branches. Has anyone seen this trait be carried on to clones? I'm surprised this hasn't been breed into the strains.