Comfrey: The Comforting Herb

Where Can You Find Russian Comfrey (Symphytum X Uplandicum) for Sale in the U.S.?

Does anyone know where to find Russian Comfrey (symphytum x uplandicum)? I hear it is the best for repairing bones, teeth, etc. I thought I had the right Comfrey before (symphytum officinale), but I recently heard that that form of Comfrey is best for inflammation, not tissue repair. I really need some help finding Russian Comfrey here in the States.