Symphytum x uplandicum  Perennial.  Perennial Growing Zones 4-8.  This is NOT the invasive variety AKA prickly comfrey. We received our initial rootstock from Strictly Medicinal Seeds, and have been propagating since at our farm. Here is what they have to say "Herbaceous perennial flowering to 3 feet, a hybrid of Russian Symphytum asperum and European Symphytum officinalis. Bocking 14 cultivar of Russian Comfrey (Symphytum x uplandicum). Sterile hybrid does not make seeds."