COMFREY

Family: Boraginaceae, Symphytum officinale L.

Source: Simon, J.E., A.F. Chadwick and L.E. Craker. 1984. Herbs: An Indexed Bibliography. 1971-1980. The Scientific Literature on Selected Herbs, and Aromatic and Medicinal Plants of the Temperate Zone. Archon Books, 770 pp., Hamden, CT.

Comfrey, Symphytum officinale L., is a hardy perennial herb native to Eurasia and naturalized in North America. Also known as common comfrey, blackwort, boneset, bruisewort, gum plant, healing herb, salsify, and slippery root, this erect-growing herb can reach a height of one meter. Characteristically covered with a prickly pubescence, the plant develops flowers colored from white to purple, a thick, externally black root, and relatively large leaves.

The reported life zone of comfrey is 6 to 25 degrees centigrade with an annual precipitation of 0.5 to 2.7 meters and a soil pH of 5.3 to 8.7 (4.1-31). The plant grows best in a moist environment and is found wild along rivers.

Although long grown for medicinal and nutritional properties, comfrey is sometimes used as an ornamental and culinary herb. Fresh leaves are used as a salad green, and the dried roots can be combined with dandelion and chicory for use as a noncaffinated coffee. Symphytum officinale L. cv. variegatum is a commercially available ornamental with white variegated leaves. Comfrey can be used as a fodder crop for livestock.

The roots and leaves of the plant have been used medicinally as an astringent, demulcent, emollient, and expectorant, and against digestive disturbances, ulcers, internal inflammations, bleeding, and cancer (14.1-13). The "healing herb" name comes from the traditional external application of comfrey to heal injured tissue and bones. The plant root has a large content of mucilage, allantoin, symphytine, echimidine, isobauerenol, -sitosterol, tannins, and lasiocarpine (11.1-136). The tannins are undoubtedly responsible for astringent properties of the plant parts, and the allantoin in the mucilage accounts for the demulcent activity. The pyrrolizidine alkaloids are potentially toxic, known to cause hepatotoxicity and to be carcinogenic (11.1-154). Whether the small to moderate amounts ingested by humans are harmful is still under debate. Comfrey leaves have been used as an adulterant with foxglove leaves (11.1-50).

Russian comfrey, Symphytum uplandicum Nym. (formerly Symphytum peregrinum), is the result of a cross between Symphytum officinale and Symphytum asperum (prickly comfrey) and is a tall herb growing up to two meters in height. Its lilfe zone is between 12 and 18 degrees centigrade, with an annual precipitation of 0.5 to 2 meters and a soil pH of 5.3 to 6.8 (4.1-31). The plant likes a moist environment and is found growing wild along rivers. Considered a hardy perennial, Russian comfrey can be grown in colder northern temperate climates. Symphytum caucasicum is a commercially available ornamental herb with blue flowers.

[Note: References listed above in parentheses can be found in full in the original reference].

Last modified 6-Dec-1997