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Seneca snakeroot: an important medicinal plant. (Gardening In General).

The root of seneca snakeroot (Polygala senega L.) has been used for centuries by aboriginal peoples in North America as a treatment for various ailments. It was introduced into European medicine in the early 1700's and became a highly sought after remedy for treating respiratory problems such as pleurisy. A recent resurgence of interest in natural medicines has greatly increased the global demand for seneca snakeroot. Manitoba currently supplies much of the world with seneca snakeroot. Plants are harvested from the wild, raising concerns as to the long-term sustainability of this natural resource.

Seneca snakeroot Polygala senega L. is also known as `senega snakeroot', `seneca (senega) root', `black snakeroot', or simply `snakeroot'. It is a member of the Milkwort Polygalaceae family. Polygala means `much milk', in reference to the milky secretions produced by many members of the genus. Seneca snakeroot is an erect, low-growing 10-30 cm (4 to 12 in.) high perennial herb, which each spring produces a circular spray of vertically oriented shoots from a single knotty root crown. Each shoot consists of a large number of alternate, lance-shaped leaves. The leaves are pale below and dark green above. The inflorescence is a dense, terminal, spike-like panicle. The flowers are initially greenish-white, but turn pinkish-white with age. The aromatic root, which is the portion harvested, is woody and twisted with numerous lateral branches.

Seneca snakeroot is native to North America. The plant occurs in open to partially shaded habitats such as prairies, open woods and roadsides, and prefers limestone-base, non-acid soils. It is common in southern and west-central Manitoba as far north as Flin Flon and Grand Rapids. The species also occurs in Saskatchewan, Alberta, southern Ontario and Quebec, and in the St. John River valley of New Brunswick. In the United States, it is found from North Dakota and Maine in the north, to Georgia and Tennessee in the south. Seneca snakeroot was probably once more widely distributed than it is today. Many native elders describe collecting seneca root from areas that are now under intensive cultivation. It is thought that agricultural practices have greatly reduced the land available for natural seneca growth.

History of Use as a Medicine

A number of native groups in eastern-central North America used seneca snakeroot for the treatment of specific ailments. It was most notably used in the treatment of rattlesnake bites, the root being first chewed and then applied to the bite as a paste. The Winnebago and Dakota peoples used snakeroot in the treatment of insect stings and poisoning. The Seneca Indians also used the root to make a tea, which was drunk as a treatment for coughs, sore throat and colds. The boiled root `bark' was made into a tea and used as an abortifacient by the Ottawa and Chippewa peoples. The Nishinam boiled the entire plant and drank the liquid as a diarrhetic. The boiled root was used to treat heart trouble by the Mesquakies and Potawatomis. The dried root of seneca snakeroot was used as a charm and carried as a talisman by the Chippewa and other native peoples.

The first dated account of seneca snakeroot by Europeans was that of Rev. J. Clayton in 1687. He mentions snakeroot as one of forty herbs "of great secret" shown to him by natives in Virginia. In the early 1700's, a Virginia doctor named John Tennent began using the root as a treatment for pleurisy and pneumonia. He had observed the Seneca Indians using the root on rattlesnake bites, and noted that the symptoms of the bites were similar to respiratory disorders. In 1736 Tennent published `An Essay on the Pleurisy' in which he described and promoted the medicinal virtues of seneca snakeroot. At the time, pleurisy was the most epidemic disease in colonial Virginia. Although respected by many Virginian colonists, Tennent's experiments with seneca snakeroot caused considerable controversy amongst his fellow physicians. In response, Tennent travelled to London in 1737 with a supply of seneca snakeroot. He was well received, and some of his material was sent to the Royal Society of Paris where its effectiveness as a treatment for pleurisy was demonstrated. Tennent returned to Virginia in 1737, but his personal and financial situations did not improve. He later returned to England, where he died in 1748 a bitter and broken man. Seneca snakeroot came to be widely used in North America and Europe following his death. By the early 1800's the plant had attracted a great deal of attention from the medical public, and was exported in large quantities to European apothecaries. It was used as an effective diuretic and expectorant, and in the treatment of rheumatism, dropsy, typhus, asthma and many other diseases.

In 1909, the dried root sold for fifty-five to seventy cents per pound. Manitoba was a major supplier of wild seneca snakeroot from the late 1800's to mid-1950's. Harvesting peaked in 1930 at about 730,000 pounds of dried root, but dropped off to about 150,000 pounds by the mid-1950's. During the 1950%, seventy-five percent of the world's supply of the root was harvested from the Interlake region of Manitoba, providing an annual income of $150,000 to the local aboriginal peoples.

In the 1920%, seneca snakeroot was used in patent medicines to treat bronchitis, often in combination with other natural expectorants. In the mid-1950's, seneca snakeroot was the main ingredient in a number of patent medicines and cough syrups. Demand for seneca snakeroot declined after 1960, and by the mid-1960's the harvest in Canada was no longer commercially important. This reduction in demand was largely attributable to the introduction of cheaper, chemically synthesized expectorants. However, a resurgence of interest in natural product medicine has resulted in a huge increase in the harvesting of wild seneca snakeroot in Manitoba in recent years.

Medicinal Properties

The principal active constituents of seneca snakeroot (known pharmaceutically as Radix Senegae) are known as saponin glycosides. These compounds produce a soap-like froth when mixed with water. Saponins are irritating to the gastric mucosa, causing secretion of mucus in the bronchioles. Seneca is therefore classified as an expectorant and is recommended in the treatment of respiratory disorders. Seneca snakeroot is used as an expectorant, diaphoretic, sialagogue and emetic in the treatment of colds, asthma and bronchitis. It is generally administered as an infusion, liquid extract or tincture. It is also an ingredient in natural toothpastes and cough medicines.

Harvesting and Processing

The provinces of Manitoba and Saskatchewan have long been major suppliers of wild seneca snakeroot. Plants from the Canadian prairie provinces are known commercially as the `Northern' or `Manitoba' variety, and are held in high esteem due to the large size of their roots. The taproots of seneca snakeroot are generally dug up in the early summer, when the plants are in flower and more easily recognized. Diggers of seneca snakeroot often travel along roadsides in the Interlake region of Manitoba, equipped with a spade and a burlap bag tied around their waist. The freshly collected roots are dried indoors on racks. The roots dry to about one-third of their fresh weight. In Manitoba populations, it takes 30-40 roots to produce one dry pound. The dried material is then shipped to processors, who powder the root for inclusion in many herbal and medicinal products.

Cultivation

Seneca snakeroot has not been widely cultivated in North America, but successful commercial plantings of seneca snakeroot and related species have been reported from Japan, China, India and Russia. Cultivated plants take from 5 to 7 years to produce a commercially harvestable root. The plant can be grown from seed, or propagated from shoot cuttings taken from mature wild plants. Very small wild plants can also be dug up and transplanted, but great care must be taken not to damage the deep taproot. Plants should only dug up from disturbed habitat such as roadside ditches, never from native prairie habitat.

Seneca snakeroot is an attractive ornamental plant. It produces a spray of deep green shoots in early spring. Each shoot is terminated by an inflorescence of 10-50 small, whitish-pink flowers. Seneca snakeroot is a low-growing and non-invasive plant that thrives in full to partial sunlight. Trails by one of us (N. Kenkel) indicate that the species grows well in Winnipeg, and makes a fine addition to a native garden. But be warned that the early spring shoots are a favourite food of rabbits!

Seed Germination

1. In moist sand, cold-stratify (at 3[degrees]C) freshly collected dried seed for at least 60 days. (That is maintaining at a cold temperature in lieu of winter.)

2. After stratification, remove seeds and rinse with a weak bleach solution for 1-2 minutes (1 part bleach to 20 parts water). This helps reduce fungal attack.

3. Rinse seeds and soak overnight in water. Remove seeds from water, and wash again in a weak bleach solution for one minute.

4. Using a sharp scalpel or razor blade, carefully slice open the seed coat. Try to remove the lower half of the seed coat. Be very careful not to cut too deeply into the seed.

5. Place the seeds on moist filter paper in sealed petri dishes. Place the dishes in a growth chamber or on a warm, south-facing windowsill. We recommend adding a commercial fungicide.

6. Allow seeds to germinate, letting the root grow to about 7-10 mm (3/8 in.) in length (germination rate should be 60-80%).

Carefully plant the rooted seedlings into a commercial soil mixture. Keep the soil moderately moist, and cover the seedlings with a plastic greenhouse lid for the first month to prevent desiccation. Optimal conditions: temperatures of 20-25[degrees]C; (68 to 77[degrees]F) twelve to fourteen hours of daylength (moderately strong light). Plants appear to do better when grown in constant-environment growth chambers for the first month. Seedlings may be lost due to fungal attack and/or desiccation; watch them carefully!

Month-old seedlings can be grown under lights or natural light for about 4 months. They should then be placed in a cold room to `overwinter' 3[degrees]C (37.4[degrees]F) for about two months or so). When the are brought back into the light, they will produce a number of side shoots and can be planted outdoors.

Shoot Cuttings

Propagation by shoot cuttings is a quick and easy way to produce robust, healthy plants. Shoot cuttings must be taken from mature plants in the very early spring. Harvested shoots should be no longer than three to five cm in length, and should consist only of newly developed leaves or (better still) leaf primordia. More fully developed shoots, particularly those having entered the early flowering stage, will not root well. Shoots should be removed from the base of a healthy plant usage a sharp, sterilized razor blade. Treat the cut ends of freshly harvested shoots with a commercial root starter, preferably one with a fungicide. Immediately plant the cuttings into a commercial non-acidic greenhouse soil. Water regularly but not excessively, and protect from full sunlight until the root system has a chance to develop. After a few months, place the cuttings in a cold room to `overwinter' (or outside, but protected). The next spring, plants will produce multiple (two to five) shoots.

Additional Readings

Briggs, C. J. 1988. Senega snakeroot. A traditional Canadian herbal medicine. Canadian Pharmacy Journal 121:199-201.

Erichsen-Brown, C. 1979. Use of plants for the past 500 years. Breezy Creek Press, Aurora, Canada. Pages 359-362.

Hlady, W. M. and B. R. Poston. 1959. A study of the population of Indian ancestry living in Manitoba. Appendix II. The people of Indian ancestry in rural Manitoba. Department of Agriculture and Immigration, Winnipeg. Pages 79-86.

Jellison, R. M. 1963. Dr. John Tennent and the universal specific. Bulletin of the History of Medicine 37:336-346.

Kindscher, K. 1992. Medicinal Wild Plants of the Prairie. Univ. Kansas Press, Lawrence. Pages 164-168.

Millspaugh, C. F. 1974. American Medicinal Plants. Dover Publications, New York. Pages 174-178.

Shipley, N. 1956. The Hidden Harvest. Canadian Geographical Journal $2:178-181.

Professor Norm Kenkel and Candace Turcotte of the Department of Botany, University of Manitoba, contributed this article, a follow-up on one we printed in the 1999 Prairie Garden.
COPYRIGHT 2001 This material is for informational use. Views are not those of the editorial committee. Reference to commercial products is made with no discrimination intended or endorsement by The Prairie Garden.
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Copyright 2001 Gale, Cengage Learning. All rights reserved.

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Author:Kenkel, Norm; Turcotte, Candace
Publication:Prairie Garden
Geographic Code:100NA
Date:Jan 1, 2001
Words:2025
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