Botanical Origin—Althæa officinalis L., the marshmallow, grows in moist places throughout Europe, Asia Minor, and the temperate parts of Western and Northern Asia, but is by no means universally distributed. It prefers saline localities such as in Spain the salt marshes of Saragossa, the low-lying southern coasts of France near Montpellier, Southern Russia, and the neighbourhood of salt-springs in Central Europe. In southern Siberia Althæa has been met with by Semenoff (1857) ascending as high as 3,000 feet in the Alatau mountains, south of the Balkash Lake.
In Britain it occurs in the low grounds bordering the Thames below London, and here and there in many other spots in the south of England and of Ireland.
The cultivated marshmallow thrives as far north as Throndhjem in Norway, and has been naturalized in North America (salt marshes of New England and New York) and Australia. It is largely cultivated in Bavaria and Württemberg.
History—Marshmallow had many uses in ancient medicine, and is described by Dioscorides as Άλθαία, a name derived from the Greek verb ἀλθειν, to heal.
The diffusion of the plant in Europe during the middle ages was promoted by Charlemagne who enjoined[373] its culture (a.d. 812) under the name of “Mismalvas, id est alteas quod dicitur ibischa.”
Description—The plant has a perennial root attaining about a foot in length and an inch in diameter. For medicinal use the biennial roots of the cultivated plant are chiefly employed. When fresh they are externally yellowish and wrinkled, white within and of tender fleshy texture. Previous to drying, the thin outer and a portion of the middle bark are scraped off, and the small root filaments are removed. The drug thus prepared and dried consists of simple whitish sticks 6 to 8 inches long, of the thickness of the little finger to that of a quill, deeply furrowed longitudinally and marked with brownish scars. Its central portion, which is pure white, breaks with a short fracture, but the bark is tough and fibrous. The dried root is rather flexible and easily cut. Its transverse section shows the central woody column of undulating outline separated from the thick bark by a fine dark outline shaded off outwards.
The root has a peculiar though very faint odour, and is of rather mawkish and insipid taste, and very slimy when chewed.
Microscopic Structure—The greater part of the bark consists of liber, abounding in long soft fibres, to which the toughness of the cortical tissue is due. They are branched and form bundles, each containing from 3 to 30 fibres separated by parenchymatous tissue. Of the cortical parenchyme many cells are loaded with starch granules, others contain stellate groups of oxalate of calcium, and a considerable number of somewhat larger cells are filled with mucilage. The last named on addition of alcohol is seen to consist of different layers.
The woody part is made up of pitted or scalariform vessels, accompanied by a few ligneous cells and separated by a parenchymatous tissue, agreeing with that of the bark. On addition of an alkali, sections of the root assume a bright yellow hue.
Chemical Composition—The mucilage in the dry root amounts to about 25 per cent. and the starch to as much more. The former appears from the not very accordant analysis of Schmidt and of Mulder to agree with the formula C₁₂H₂₀O₁₀, thus differing from the mucilage of gum arabic by one molecule less of water. It likewise differs in being precipitable by neutral acetate of lead. At the same time it does not show the behaviour of cellulose, as it does not turn blue by iodine when moistened with sulphuric acid, and it is not soluble in ammoniacal solution of oxide of copper.