Was harvesting/processing fresh kava roots the other day and I couldn't find this info, once you get the roots chopped off, your left with a large portion of stump between the roots and the upper aerial parts of the plant, I am all most positive you can use the stump, but it's just not as potent, I think the toxic parts are mostly the aerial parts, the original guy who sold me fresh roots said the micronesians always use that part, that part is smaller but probably at least double the weight of all the roots you get off, could get a hell of alot more drink out of it, anyone remember what the info on that is?