Howdy nl16, and welcome to the forum.
I have not heard of starting a cannabis plant from a root, but I do know that it happens in nature all of the time. I have a 'volunteer' pecan tree that sprouts up every spring. It is right next to my patio, so I mow it down every year, but it keeps coming back from only the roots. If You provided the right conditions, light, heat, and nutrients (including some sugars) it might start growing. I am not a botanist either, so I do not know if the pecan, being an perennial, and the cannabis being an annual type of plant would make any difference or not. You might try it to see?