It is the common comfrey (Symphytum officinale L.).
Over centuries, this species was cultivated in Asia, Europe, and the United Kingdom as a vegetable and herbal medicine. Its early common names, knitbone or boneset, reflect its historical use by poultices of leaves and roots to treat sprains, bruises or bone fractures. In particular, the use of the root has a longstanding tradition. Today, several randomised controlled trials have demonstrated the efficacy and safety. Comfrey root extract has been used for the topical treatment of painful muscle and joint complaints.
