(A lot of plants in the Boraginaceae contain hepatotoxic pyrrolizidine alkaloids. Comfreys are among them. More info here: Livertoxic PAs --Henriette.)
OTHER COMMON NAMES—Symphytum, healing herb, knitback, ass-ear, backwort, blackwort, bruisewort, gumplant, slippery-root.
HABITAT AND RANGE—Comfrey is naturalized from Europe and occurs in waste places from Newfoundland to Minnesota, south to Maryland.
DESCRIPTION OF PLANT—Th is coarse, rough, hairy, perennial herb is from 2 to 3 feet high, erect and branched, with thick, rough leaves, the lower ones ovate lance shaped, 3 to 10 inches long, pointed at the apex, and narrowed at the base into margined stems. The uppermost leaves are lance-shaped, smaller and stemless. Comfrey is in flower from June to August, the purplish or dirty white, tubular, bell shaped flowers numerous and borne in dense terminal clusters. The nutlets which follow are brown, shining and somewhat wrinkled. Comfrey belongs to the borage family (Boraginaceae.)
DESCRIPTION OF ROOT—Comfrey has a large, deep, spindle-shaped root, thick and fleshy at the top, white inside and covered with a thin, blackish brown bark. The dried root is hard, black and very deeply and roughly wrinkled, breaking with a smooth, white, waxy fracture. As it occurs in commerce it is in pieces ranging from about an inch to several inches in length, only about one-fourth of an inch in thickness, and usually considerably bent. It has a very mucilaginous, somewhat sweetish and astringent taste, but no odor.
COLLECTION, PRICES AND USES—The root is dug in autumn, or sometimes in early spring. Comfrey root when first dug is very fleshy and juicy, but about four-fifths of its weight is lost in drying. The price ranges from 4 to 8 cents a pound,
The mucilaginous character of Comfrey root renders it useful in coughs and diarrheal complaints, Its action is demulcent and slightly astringent. The leaves are also used to some extent.
Ginseng and Other Medicinal Plants, 1936, was written by A. R. Harding.