48. Acorus Calamus, Linn.—Common Sweet Flag.
Sub-order II. Callaceae, Endl.
Perfect stamens associated with ovaries in hermaphrodite florets.
Sex. Syst. Hexandria, Monogynia.
(Rhizoma, L.—Rhizome, E.)
History.—This is probably the ακορον of Dioscorides. [Lib. i. cap. 2.] Dr. Koyle says that in Persian works akoron is given as its Greek appellation. It must not be confounded with the καλαμος αρωματικος of Dioscorides, which, according to Dr. Royle, [Essay on the Antiq. of Hindoo Med p. 33.] is Andropogon Calamus aromaticus, Royle (see ante, p. 154).
Botany. Gen. Char.—Flowers arranged upon a spadix. Spathe replaced by a two-edged leaf-blade. Perianth of 6 pieces or scales, inferior, persistent. Stamens 6, filiform. Stigma sessile. Ovaries 2- 3-celled. Berries 1-celled, 1- 3-seeded. Seeds albuminous.
Sp. Char.—Spathe, a continuation of the 2-edged scape, rising much above the spadix.
Rhizome thick, rather spongy, with many long roots, aromatic, like every part of the herbage, but much more powerfully so. Leaves erect, two or three feet high, bright green, near an inch broad. Stalk like the leaves, except being thicker below the spadix, and not quite so tall. Spadix about a foot above the root, a little spreading, two or three inches long, tapering, covered with a mass of very numerous, thick-set, pale green flowers, which have no scent, except when bruised. A very narrow wavy membrane may be observed at the base of the spadix, which perhaps ought to be taken into the generic character as a spathe (Smith).—Perennial: flowers in June.
Hab.—It is a native of this country, growing in watery places about the banks of rivers, and is very plentiful in the rivers of Norfolk, whence the London market was formerly supplied. It grows, also, in other countries of Europe, in Asia, and in the United States.
Description.—The dried underground stem (rhizoma, L.; radix acori veri seu radix calami aromatici, Offic.) occurs in the shops in flattened pieces four or five or more inches long, and about as broad as the thumb; jointed, somewhat curved, of a spongy or corky texture internally; of a yellowish brown or fawn colour externally, and buffy, with a slight roseate hue, internally. Their fracture is short: their upper surface is marked transversely with the vestiges of the leaves which were attached to it; the lower surface has numerous dark points, surrounded by small light-coloured elevated circles, from which the roots arise. Their taste is warm and bitter; their odour is aromatic. In Germany, the rhizome is usually peeled before drying it (rhizoma decorticata); but the operation is unnecessary and wasteful. In this state, the rhizome is grayish-white and easily pulverizable.
The rhizome should be gathered in spring or late in the autumn, and dried quickly. It is usually gathered on the banks of the Thames about May for the London market.
The fresh rhizome is employed for distillation. The pieces are sometimes fourteen or fifteen inches long, and one inch wide.
The rhizome of the Yellow Water Iris (Iris Pseudo-acorus) is said to be sometimes substituted for that of the true Acorus.
Composition.—The fresh rhizome was analyzed by Trommsdorff, [Gmelin, Handb. d. Chem. ii. 1339.] who obtained the following results: Volatile oil, 0.1; soft resin, 2.3; extractive, with a little chloride of potassium, 3.3; gum, with some phosphate of potash, 5.5; starchy matter (like inulin), 1.6; woody fibre, 21.5; and water, 65.7. Meissner found traces of copper in the ashes.
The active constituents are the oil, the resin, and the extractive.
Oil of the Common Sweet Flag (oleum acori calami, called, in the shops, oleum calami aromatici) is obtained by distilling the fresh rhizome with water. Its odour is similar to, though less agreeable than, that of the rhizome. Its colour is yellow. It is bought by snuffmakers, so that it is used, I presume, for scenting snuff. It is also employed in the preparation of aromatic vinegar.
Chemical Characteristics.—Iodine blackens the rhizome (especially when it has been boiled), thereby indicating the presence of starch. The cold decoction of the rhizome forms, with a solution of iodine, the blue iodide of starch. Acetate and diacetate of lead, and protonitrate of mercury, cause precipitates with the decoction. These precipitates consist principally of metallic oxides or subsalts, and the substance called extractive. Nitrate of silver produces a precipitate (chloride of silver), which is insoluble in nitric acid, but soluble in ammonia. The decoction reddens litmus.
Physiological Effects.—It is an aromatic stimulant and mild tonic. Vogt [Lehrb. d. Pharmakodyn. i. 454, 2te Aufl.] arranges it with the excitantia volatilia, and regards it as approaching angelica root on the one hand, and cascarilla and angustura barks on the other.
Uses.—It is rarely employed by medical practitioners, though it might be frequently substituted, with good effect, for the more costly oriental aromatics. It is a useful adjunct to other stimulants and tonics. It has been employed in continued asthenic fevers accompanied with much prostration of strength and greatly weakened digestive power. For the cure of ague, the dried root powdered is used by the country people in Norfolk. [Sir J. E. Smith, Engl. Flora, ii. 158.] It is well adapted for dyspeptic cases accompanied with, or dependent on, an atonic condition of the digestive organs, and is especially serviceable in gouty subjects. It has also been used as a local agent, viz., in the formation of aromatic baths, poultices, and gargles, as an application to foul-conditioned ulcers, &c. It is employed, I am informed, by some rectifiers to flavour gin.
Administration.—In powder, the rhizome may be given in doses of from a scruple to a drachm. The infusion is, perhaps, the most eligible preparation; it is made by digesting ℥j of the rhizome in ℥xij of boiling water; the dose is two or three tablespoonfuls. The decoction is an objectionable preparation, as the oil of the rhizome is dissipated by boiling. The tincture (Ph. Bor.) is procured by digesting ℥ij of the rhizome in ℥xij of spirit (sp. gr. 0.900); the dose is a teaspoonful.