Medical Herbs Catalogue



Botanical Name: Polygala Senega (LINN.)
Family: N.O. Polygalaceae

Synonyms: Snake Root. Senegae Radix. Seneca. Seneka. Polygala Virginiana. Plantula Marilandica. Senega officinalis. Milkwort. Mountain Flax. Rattlesnake Root.
Part Used: Dried Root.
Habitat: North America.

Description: This perennial herb, about a foot high, grows throughout central and western North America, in woods, and on dry, rocky soil. The leaves are small alternate, and narrowly lanceolate, and the numerous, small pinky-white flowers are crowded on to a narrow, terminal spike from 1 to 2 inches long.

The name of the genus, Polygala, means 'much milk,' alluding to its own profuse secretions and their effects. 'Senega' is derived from the Seneca tribe of North American Indians, among whom the plant was used as a remedy for snake-bites.

The root, varying in colour from light yellowish grey to brownish grey, and in size from the thickness of a straw to that of the little finger, has as its distinguishing mark a projecting line, along its concave side. It is usually twisted, sometimes almost spiral, and has at its upper end a thick, irregular, knotty crown, showing traces of numerous, wiry stems. It breaks with a short fracture, the wood often showing an abnormal appearance, since one or two wedge-shaped portions may be replaced by parenchymatous tissue, as if a segment of wood had been cut out. The keels are due to the development of the bast, and not to any abnormality in the wood. The odour and taste resemble that of Wintergreen.

About 1735, Dr. John Tennent, a Scottish physician living in Pennsylvania, was introduced to the use of the root by the Seneca Indians for curing rattlesnake-bite. As the symptoms were similar to those of pleurisy and the latter stages of pleuropneumonia, he experimented with it in those diseases with success, and as a result the drug was accepted in Europe and cultivated in England in 1739. The roots should be gathered when the leaves are dead, and before the first frost. From carelessness in collection other roots are often found mixed with it, but not for intentional adulteration. The root of commerce is obtained from Polygala latifolia also, this species being several inches taller and having larger leaves than P. Senega. The dried roots, usually in broken pieces, are brought into market in bales weighing from 50 to 400 lb. They vary a little in appearance according to their locality. The official Senega is the small Southern Senega, 400 to 500 of the dried roots of which are required to make a pound. Manitoba Senega is larger and darker, often with purple markings near the crown. The Northern, White, False, or Large Senega, comes from Wisconsin, Minnesota, and farther west. About 80 to 100 of its roots will make a pound. It is stated that it is not possible to distinguish the two when powdered.

Constituents: The root contains polygalic acid, virgineic acid, pectic and tannic acids, yellow, bitter, colouring matter, cerin fixed oil, gum, albumen, woody fibre, salts, alumina, silica, magnesia and iron. The powder is yellowish-grey to light yellowishbrown.

The active principle, contained in the bark, is Senegin (which some authorities regard as another name for polygalic acid, while others differentiate between the two). It is a white powder easily soluble in hot water and alcohol, forming a soapy emulsion when mixed with boiling water. It is almost identical with the saponin of Saponaria officinalis and Quillaria Saponaria. Thus its influence counteracts, or can be counteracted, by digitalis.

Another analysis, in 1889, gives fixed oil and resin, traces of volatile oil (a mixture of valeric ether and methyl salicylate), 7 per cent sugar, from 2 to 5 per cent senegin, yellow colouring-matter, and malates.

It is advisable to use an alkali in small proportion in making galenical preparations of senega.

Oil of Senega is bitter, rancid, and disagreeable, with the consistency of syrup and an acid reaction. It is not Seneca oil.

Medicinal Action and Uses: A stimulating expectorant, diuretic and diaphoretic. The Ancients regarded its action as identical with that of ipecacuanha, but in doses of three times the strength. It should be used when the power to expectorate is small - very useful in the second stage of acute bronchial catarrh or pneumonia. It is of little value when the expectoration is tough and scanty, but very helpful in chronic pneumonia or bronchitis or dropsy dependent on renal disease. Spirit of chloroform will lessen its disagreeable taste. It has been used also in croup, whooping-cough, and rheumatism.

As it stimulates most of the secretions, it is also useful as a sialagogue and emmenagogue. In active inflammation its use is contraindicated.

In large doses it is emetic and cathartic.

Dosages: Powdered root, 5 to 20 grains. Fluid extract, 10 to 20 drops. Of infusion, B.P., 4 to 8 drachrns. Of syrup, U.S.P., 1 drachm. Of tincture, B.P., 1/2 to 1 drachrn. Conct. Solut., B.P., 1/2 to 1 drachm.

Poisons and Antidotes: In overdose it can act as an irritant or general protoplasmic poison, with violent vomiting and purging. A dose of from 10 minims of the tincture to a scruple of the powdered root will cause heaviness and vertigo, dazzling vision, sneezing, inflammation of the oesophagus, withconstriction, thirst, nausea, mucous vomiting, colic, scalding, frothy urine, irritation of the larynx, and general debility. Like saponin, it causes a paresis of the muscles of the respiratory tract and the vaso-motor system in general, resulting in capillary congestions followed by rapid exosmosis.

Adulterations and Other Species:
Panax quinquefolium, or American Ginseng Root, is the most common admixture. It is larger and has no ridge.

Various species of Gillenia, Asclepias Vincetoxicum, or Swallow-wort, Triosteum perfoliatum, and the rhizome of Cypripedium pubescens have also been found in parcels. They have a different taste and odour, and show no ridge.

P. Boykinii or P. Alba resemble P. Senega, but have no ridge and are much less acrid.

Arnica, Valerian, Serpentary and Green Hellebore roots resemble it, but have no keel.