The genus name for comfrey is Symphytum, which means to “unite or knit together.” The name com-firma means simply, “knitting of bones.” You can use the leaf and the root, fresh or dried.
Comfrey contains a special substance called allantoin, which is a cell proliferative. In other words, it makes cells grow faster. This is one of the reasons why comfrey-treated bones knit so fast, wounds mend so quickly and burns heal with such little scarring. Comfrey is often called knitbone or healing herb.