This section is from the book "A Treatise On Therapeutics, And Pharmacology Or Materia Medica Vol2", by George B. Wood. Also available from Amazon: Part 1 and Part 2.
The marshmallow, Althaea officinalis, is an herbaceous perennial plant, growing in low grounds, and on the borders of salt marshes, in Europe and the United States. The U.S. Pharmacopoeia of 1850 recognized the flowers and root (Althaeae Flores, and Althaeae Radix, U. S. 1850); the London, the root only; the Edinburgh, the root and the leaves. Our Pharmacopoeia now directs only the root; and the British has unaccountably omitted the medicine altogether. All parts of the plant abound in mucilage, and all may be employed; but it is chiefly the root which is used in the United States. it is imported.
Marshmallow root is in somewhat cylindrical or split pieces, several' inches long, about as thick as the little finger, destitute of bark, of a downy appearance on the outside, white, of a slight peculiar odour, and of a sweetish taste. it imparts mucilage to the saliva when chewed.
Marshmallow is employed simply as a demulcent; and its applications are those of the class generally; so that they need not be repeated. The root is used in decoction, which may be prepared by boiling an ounce in a pint of water down to twelve fluidounces.