Comfrey contains livertoxic pyrrolizidine alkaloids. Don't use it. More info here: Livertoxic PAs --HenrietteNames. Common Comfrey.
Fr. Consoude usuelle.
Classif. Nat. Order of Borragines or Asperifolia. Pentandria monogynia L.
Genus SYMPHYTUM. Calyx five parted, persistent. Corolla funnel shaped, limbus tubulate ventricose, orifice closed by 5 subulate appendages. Five stamina in the tube. Pistil 4 lobed, one style and stigma. Four seeds.
Sp. Symphytum officinale. L. Stem erect and winged: leaves oval lanceolate, all sessile, decurrent, acute, rugose: racemes nodding, glomerated, and secund.
Description. Root perennial, whitish, thick, cylindrical, tapering or branched. Stem 3 or 4 feet high, upright, branched, angular and winged, rough; branches erect. Leaves alternate, sessile decurrent, oblong, attenuated, and rugose. Flowers in terminal racemes, glonerated, nodding, recurved. Corolla yellowish white, base tubular, end ventricose, 5 toothed.
History. This plant is a native of Europe, but has been naturalized from New England to Ohio and Virginia, growing spontaneously in thickets, meadows, &c. It blossoms in June and July. The varieties are, 1. Purpureum, with purple flowers and spreading calyx. 2. Nigrum, root black. 3. Elatior. 4. Pumilum. 5. Albiflorum.
We have a native American species of this genus, found west of the Mississippi, in the prairies and glades, and cultivated at Bartrams garden. I call it and distinguish as follows:
Symphytum hirsutum. Whole plant hirsute. Stem erect, somewhat winged, lower leaves petiolate, oblong lanceolate, upper leaves sessile decurrent, oval acuminate; racemes germinate, erect, convolute at the end. Size 4 feet, lower leaves a foot long, flowers white.
Properties. The whole plant, but chiefly the roots are in use; the S. hirsutum is probably equivalent. They have no smell; the taste is mucilaginous, glutinous, a little sweetish, and austere, but grateful. The principles are mucilage, fecula, gallic acid, &c. They are inspissant, demulcent, vulnerary, astringent, and beneficial in dysentery, nephritis, haematoma, hemoptysis, strangury, and many other diseases internally, while externally they are useful bruised and applied to ruptures and sprains. The mucilage of these roots is equal to that of Althea or Marshmallows, but much more useful, being united to astringency. The Comfrey may be used with great advantage in hemorrhage of the bowels, stomach, and lungs, erosions of the intestines, salt rheum, gonorrhea, and fluor albus, ardor of urine, &c. It is much valued in Europe and China, also by our herbalists, but wrongly omitted by all our medical writers, except Schoepf and Cutler. In China it is called Tihoang, and considered equal to Ginseng in many cases, particularly in preserving health; pills, lozenges, and bolus are made of it, and taken daily in the morning, by people of weak and debilitated habits. In Europe, a conserve and syrup is used. The infusion, decoction, &c. are equally good; the doses need not be very nice, as the effects are mild. Our herbalists unite it to Burdock and Yarrow, to cure the clap, using at the same time injections of Statice or Tormentil. Boiled in milk, it becomes the best preparation for diseases of the bowels and urinary organs. It may be safely employed in all diseases of debility, relaxation, and overflowing. It is said to act as a palliative at least in nephitic pains and gravel, to prevent the recurrence of bleeding from the lungs and stomach, and to strengthen while it lubricates all the solids.
Medical Flora, or Manual of the Medical Botany of the United States of North America, Vol. 2, 1830, was written by C. S. Rafinesque.