THE peculiar form and arrangement of the leaves in this plant render it very easy of distinction at sight by the most inexperienced botanist. It flowers from midsummer to September, and is found in all latitudes from Nova Scotia to Florida. It inhabits meadows and boggy soils, growing most frequently in bunches, the stems being connected by horizontal roots. Its common names are Thorough wort, Thorough wax, Cross wort. Bone set, &c.
The genus Eupatorium, belonging to the first order of the class Syngenesia or Compound flowers, and to the order Corymbiferae of Jussieu, is characterized by its naked receptacle, its down simple or rough, its calyx oblong and imbricate, its style longer than the corolla, and cloven half way down. The species perfoliatum, exclusively an inhabitant of America, is abundantly distinguished from the rest, by the pecuiar form of its leaves, indicated in its name. Michaux has altered the specific name to connatum I think injudiciously.
The stems of this plant are erect, round, hairy branched at top only. The leaves, which are perforated by the stem, are rather perfoliate than connate, since they have not the character of two leaves joined together, but of one entire leav, having its four principal veins proceeding at right angles from the four quarters of the stem, two of them being situated in the place of the supposed junction. The upper leaves however are generally divided into pairs. The main leaves are acuminate, decreasing gradually in breadth from the stem, where they are widest, to the extremities. They are serrated, wrinkled, pale underneath, and hairy, especially on the veins. Flowers in corymbs with hairy peduncles. Calyx cylindrical, imbricate, the scales lanceolate, acute, hairy. Each calyx contains about twelve or fifteen florets, which are tubular, with fine spreading segments, and surrounded with a rough down. The stamens in each consist of five soft filaments, with blackish anthers united with a tube. Style filiform, divided into two branches, which project above the flower. Seeds oblong on a naked receptacle.
Every part of the Eupatorium has an intensely bitter taste, combined with a flavour peculiar to the plant, but without astrinency or acrimony. The leaves and flowers abound in a bitter extractive matter, in which the important qualities of the plant seem to reside. I find this principle to be alike soluble in water and alcohol, imparting its sensible qualities to both, and neither solution being rendered turbid, at least for some time, by the addition of the other solvent. It forms copious precipitates with many of the metallic salts, such as muriate of tin, nitrate of mercury, nitrate of silver, and acetate of lead. Of the mineral acids, the sulphuric and muriatic form slight precipitates with the aqueous decoction; the oxymuriatic, a more copious one; the nitric, in my experiments, gave no precipitate, but changed the colour to a red. In the alcoholic solution the oxymuriatic alone formed an immediate precipitate. Tannin exists very sparingly in this plant. A solution of isinglass produced a slight precipitate from the tincture, and a hardly perceptible turbidness in separate decoctions of the leaves and flowers. Sulphate of iron gave a dark green precipitate, which partially subsided in a short time.—In distillation, water came over very slightly affected with the sensible qualities of the plant, and not alterable by sulphate of iron.
A dissertation of merit on this plant was published a few years since by Dr. Anderson of New York, in which he gives the details of numerous and elaborate chemical trials, made by him on different parts of the plant. He concludes, among other things, from his experiments, that the active properties of the plant reside in greatest quantity in the leaves, and that its virtues are readily obtained by means of a simple decoction.
The medical powers of Eupatorium are such as its sensible properties would seem to indicate, those of a tonic stimulant. Given in moderate quantities, either in substance or in cold infusion or decoction, it promotes digestion, strengthens the viscera, and restores tone to the system. Like other vegetable bitters, if given in large quantities, especially in warm infusion or decoction, it proves emetic, sudorific, and aperient. Even in cold infusion it tends to bring on diaphoresis.
This plant has been long in use in different parts of the United States, for the same purposes for which the Peruvian bark, Gentian, Chamomile, &c. are employed. It has been found competent to the cure of intermittent fevers by various practitioners in the middle and southern states. Dr. Anderson has detailed six cases of intermittents, quotidian, tertian, and quartan, out of a large number which had been successfully treated within his own observation by the Eupatorium both in substance and decoction; In these cases the cures were certainly expeditious, and took place at as early a period as could have been expected from arsenic or the Peruvian bark. Dr. A. cites the experience of several distinguished practitioners, particularly Dr. Hosack of New York and the late Dr. Barton of Philadelphia, in confirmation of his own, to show that the Eupatorium is an efficacious remedy in the treatment of various febrile disorders, also of many cutaneous affections, and diseases of general debility.
I have prescribed an infusion of the Eupatorium in various instances to patients in the low stages of fever, where it has appeared instrumental in supporting the strength and promoting a moisture of the skin, without materially increasing the heat of the body. I have also found the cold infusion or decoction a serviceable tonic in loss of appetite and other symptoms of dyspepsia, as well as in general debility of the system.
The warm infusion is a convenient substitute for that of chamomile flowers in facilitating the operation of an emetic.
When employed as a tonic, this plant may be taken in powder in doses of twenty or thirty grains, or a teacup full may be used of the infusion, rendered moderately bitter. When intended to act as an emetic, a strong decoction may be made from an ounce of the plant in a quart of water, boiled to a pint.
Eupatorium perfoliatum, Linnaeus, Sp. pl.
Aiton, Hort. Kew. iii. 160.
Willdenow, Sp. pl. iii. 1761.
Colden, Novebor. 181.
Stokes, iv. 171.
Pursh, ii. 516.
Eupatorium connatum, Michaux, Fl. Amer.ii. 99.
Eupatorium Virginianum, &c.
Plukenet, t. 87. f. 6.
Morison, hist. iii. 97.
Guthrie in Annal. Med. iii. 403.
Bart. Coll. 28.
Med. and Phys. Journal.
Thacher Disp. 217.
Anderson, Inaugural Thesis.
American Medical Botany, 1817-1821, was written by Jacob Bigelow, M. D.