This section is from the book "A Treatise On Therapeutics, And Pharmacology Or Materia Medica Vol1", by George B. Wood. Also available from Amazon: Part 1 and Part 2.
This is the product of Coptis trifolia, a very small plant, with a perennial creeping root, inhabiting low and shaded places in the northern parts of this continent, and of Asia. It is abundant in our own Northern States. All parts of it have some bitterness, which, however, is strongest in the root; and this is the portion directed by the U. S. Pharmacopoeia, though, as the medicine is kept in the shops, the roots, leaves, and stems are generally intermingled. The root is long, slender, thread-like, of a deep orange-yellow colour, inodorous, and intensely and purely bitter. It yields its bitterness to water and alcohol. The medicine is closely allied to quassia in its properties, and might probably be substituted for it in all cases without disadvantage; but the smallness of the product of each plant will always be an obstacle to its general use, unless some superiority of virtues can be shown. It is sometimes used, in New England, in aphthous affections of the mouth, as a local application. The dose of the powder is from ten to thirty grains; of an infusion made with two drachms to a pint of water, one or two fluidounces; of a tincture, containing the virtues of an ounce in a pint of diluted alcohol, one or two fluidrachms.