The root of Dorstenia Contrayerva, Linné, and Dorstenia brasiliensis, Lamarck.
Botanical Source.—Dorstenia Contrayerva is a perennial caulescent plant, with a spindle-shaped root, from which arises a stem covered with spreading, green, scaly stipules. The leaves are palmate; the lobes lanceolate, acuminate, coarsely serrated and gashed, and occasionally almost pinnatifid. The receptacle is borne on a very long stalk, and is quadrangular, waivy, or plaited. The achenia are lenticular, and imbedded in the fleshy receptacle from which they are projected with elasticity when ripe (L.). The Dorstenia brasiliensis closely resembles the preceding.
History and Description.—These plants inhabit the tropical parts of South America. The root, which is the part used, is knotty and ovoid, woody, 1 or 2 inches long, of a reddish-brown color externally, and pale within; its diameter is about 1/2 an inch, and long, rough, slender fibers shoot out from all sides of it, especially its lower portion, and are generally loaded with small, brown knots. It has a peculiar aromatic odor, and a somewhat astringent, warm, bitterish taste, with some acridity when long chewed. As the fibers have but little odor or flavor they should be removed from the rhizome. It yields its virtues to alcohol, or water, at 100° C. (212° F.); the root abounds in mucilage; its tincture has an acid reaction on litmus.
The root of commerce is probably derived from several other species, which possess similar virtues, as the D. Houstoni, D. dracena, D. tubicina, and D. opifera. Monardes states that the word contrayerva is the Indo-Spanish term for alexi-pharmic or counterpoison.
Chemical Composition.—According to Geiger, the root contains volatile oil, starch, and a non-crystalline bitter, to which may be added resin, free acid, and woody fiber.
Action, Medical Uses, and Dosage.—Contrayerva is a gentle stimulant and a diaphoretic, and is sometimes given in exanthematous diseases, typhus fever, and dysentery. Its dose, in powder, is 30 grains; the best form of administration is the infusion. The Virginia snake-root is preferred to it in this country.