Botanical: Rhus Toxicodendron (LINN.)
---Synonyms---Poison Oak. Poison Vine.
Family: N.O. Anacardiaceae
---Habitat---The American Poison Ivy is one of the species of Sumachs, an attractive group of plants widely distributed in Europe, Asia and North America, varying much in habit from low bushes to moderately-sized trees, and many of them familiar denizens of our gardens, for the sake of their ornamental foliage, which mostly assume beautiful tints in autumn, some of the varieties also bearing showy fruits. It grows in thickets and low grounds in North America, where it is quite common.
Its sap is of an extremely poisonous character, and in many persons the slightest contact with the leaves causes a rash of a most distressing character, the hands and arms and sometimes the whole body becoming greatly swollen from simply touching or carrying a branch of the plant, the swelling being accompanied with intolerable pain and inflammation, ending in ulceration. Some persons however, are able to handle the plant with impunity. It has been sometimes known as Ampelopsis Hoggii, and under this name has occasionally been introduced with other climbers, but it has nothing to do with the group of Vines known under the name of Ampelopsis, and its presence in our gardens should be avoided.
---Description---The root is reddish and branching; the leaves rather large, threeparted (which will readily distinguish it from the five-parted Ampelopsis). The central leaflet has a longer stalk, the lateral ones are almost stalkless. The leaflets are entire when young, but when full-grown they are variously indented, downy beneath, thin and about 4 inches long. They abound with an acrid juice, which darkens when exposed to air, and when applied to the skin produces the inflammation and swelling referred to. When dry, the leaves are papery and brittle, sometimes with black spots of exuded juice turned black on drying. The flowers are in loose, slender clusters or panicles, in the axils of the leaves and are small, some perfect, others unisexual, and are greenish or yellowish-white in colour. They blossom in June, and are followed by clusters of small, globular, duncoloured, berry-like fruit.
There are almost as many antidotes for the inflammation caused by Poison Ivy as for the bites of the rattlesnake. Alkaline lotions, especially carbonate of soda, alum and hyposulphite of soda, are all recommended, and the patient is advised to moisten the skin constantly with the agent in solution. A hot solution of potassium permanganate applied locally is also recommended as a cure, also solutions of lead and ammonia. Rhus venenata has similar poisonous qualities.
---Part Used Medicinally---The fresh leaves, from which a fluid extract is prepared.
---Constituents---The activity of the drug was formerly ascribed to a fixed oil, Toxicodendrol, but has been attributed more recently to a yellow resin, to which the name Toxicodendrin is applied.
---Medicinal Action and Uses---Irritant, rubefacient, stimulant, narcotic.
R. Toxicodendron was introduced into England first in 1640, but not used as a medicine till 1798, when Du Fressoy, a physician at Valenciennes, had brought to his notice a young man, who had been cured of a herpetic eruption on his wrist of six years' standing on being accidentally poisoned by this plant. He thereupon commenced the use of the plant in the treatment of obstinate herpetic eruptions and in palsy, many cases yielding well to the drug. Since then it has rapidly gained a place in general practice, meeting with some success in the treatment of paralysis, acute rheumatism and articular stiffness, and in various forms of chronic and obstinate eruptive diseases.
It is not official in the British Pharmacopoeia, but was formerly official in the United States Pharmacopceia. It is in extensive use by homoeopathists for rheumatism, ringworm and other skin disorders, and is considered by them one of the most useful remedies in a great majority of cases of Nettlerash, especially if caused by some natural predisposition of constitution, in which the eruption is due to the use of some particular food.
The fluid extract, prepared from the fresh leaves, is mostly given in the form of a tincture, in doses of 5 to 30 drops. In small doses it is an excellent sedative to the nervous system, but must be given with care, as internally it may cause gastric intestinal irritation, drowsiness, stupor and delirium.
It has been recommended in cases of incontinence of urine. For this, the bark of the root of R. aromatica is also employed very successfully, an infusion of 1 OZ. to a pint of boiling water being taken in wineglassful doses.
The fluid extract of R. Toxicodendron can be used as a vesicant or blister producer, like cantharides, mezeron, and oil of Mustard.
The best preparation is a concentrated alcoholic tincture made from the green plant in the strength of 1 in 4. The dose of 25 per cent tincture is given in 1 to 5 drops three times a day. A solid extract is not used owing to the extreme volatility of the active principles of the crude drug.
Its milky juice is also used as an indelible ink for marking linen, and as an ingredient of liquid dressings or varnishes for finishing boots or shoes, though R. venenata is more extensively used for the latter purpose.
Common Name Index
Bear in mind "A Modern Herbal" was written with the conventional wisdom of the early 1900's. This should be taken into account as some of the information may now be considered inaccurate, or not in accordance with modern medicine.
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