158. Mentha Viridis, Linn.—Spearmint.
Sex. Syst. Didynamia, Gymnospermia.
(Herba florens recens et exsiccata. Oleum ex herba floreute destillatum, L.—Herb, E. D.)
History.—See Mentha piperita.
Botany. Gen. Char.— Calyx campanulate or tubular, 5-toothed, equal or somewhat 2-lipped, with the throat naked inside, or villous. Corolla with the tube inclosed, the limb campanulate, nearly equal, 4-cleft; the upper segment broader, nearly entire or emarginate. Stamens 4, equal, erect, distinct; filaments smooth, naked; anthers with two parallel cells. Style shortly bifid, with the lobes bearing stigmas at the points. Nucules dry, smooth (Bentham).
Sp. Char.—Stem erect, smooth. Leaves subsessile, ovate-lanceolate, unequally serrated, smooth; those under the flowers all bract-like, rather longer than the whorls; those last and the calyxes hairy or smooth. Spikes cylindrical, loose.
Whorls approximated, or the lowest or all of them distant. Teeth of the calyx linear subulate (Bentham).—Creeping-rooted.
Var. β. angustifolia, Bentham. Leaves of the branches with short petioles. Distinguished from M. piperita by the slender elongated spikes.
Var. γ. crispa, Bentham. Curled Mint. Cultivated in gardens.
Hab.—Marshy places. Indigenous. A native of the milder parts of Europe; also of Africa and America. Perennial. Flowers in August. Selected for medicinal use when about to flower.
Properties.—The whole herb, called green-mint or spearmint (herba menthae viridis), is employed in medicine. It has a strong but peculiar odour, and an aromatic, bitter taste, followed by a sense of coldness when air is drawn into the mouth. Sesquichloride of iron communicates a green colour (tannate of iron) to the cold watery infusion.
Composition.—Its odour and aromatic qualities depend on volatile oil. It also contains tannic acid, resin (?), a bitter principle, and woody fibre.
Physiological Effects.—Aromatic, carminative, mildly stimulant and tonic. Feebler than Peppermint. Said, though without sufficient foundation, to check the secretion of milk, and to act as an emmenagogue. [Linnaeus, in Murray's App. Med. vol. ii. pp. 180—1.]
Uses.—Employed as a salad and sweet herb. In medicine, it is principally used as a flavouring ingredient, and to alleviate or prevent colicky pains. The following are its officinal preparations, with their uses:—
1. INFUSUM MENTHAE VIRIDIS, D.; Infusion of Spearmint; Spearmint Tea.—(Spearmint, dried and cut small, ʒiij; Boiling Water Oss.)—Stomachic and carminative. Used in irritable conditions of the stomach; but is ordinarily a vehicle for other remedies. Dose, f℥j to f℥ij, or ad libitum.
I. OLEUM MENTHAE VIRIDIS, L. E. D. [U.S.]; Oil of Spearmint—(Obtained by submitting the fresh herb to distillation with water.)—It is of a pale yellowish colour, but becomes reddish by age. It has the odour and taste of the plant, and is lighter than water; sp. gr. 0.914. It boils at 320° F.; and is composed, according to Dr. Kane, of C35H28O. The average produce of the essential oil is not more than 1-500th of the fresh herb. [Brande, Dict. Mat. Med. p. 328.] It is carminative and stimulant. Dose, gr. ij to gtt. v, rubbed with sugar and a little water.
3. SPIRITUS MENTHAE VIRIDIS, L.; Spirit of Spearmint—(Oil of Spearmint ʒiij; Proof Spirit Cong. j. Dissolve.) Dose, fʒss to f℥ij—This preparation has no advantages over, while it is much weaker than, the more simple and elegant preparation, the essence of spearmint of the shops.
4. ESSENTIA MENTHAE VIRIDIS, D.; Essence, of Spearmint—(Oil of Spearmint f℥j; Stronger Spirit f℥ix. Mix with agitation.)—It may be coloured green by spearmint or spinach leaves. Dose, gtt. x to gtt. xx, taken on sugar or in water. [This is the same as the Tinctura Olei Menthae Viridis (U. S. Pharm.), for which the formula is, Oil of Spearmint f℥ij; Alcohol Oj. Dissolve the oil in the alcohol.]
5. AQUA MENTHAE VIRIDIS, L. E. D. [U. S.]; Spearmint Water.—(Spearmint, dried, ℔ij; Water Oij. Let a gallon distil. If the fresh herb be used, double the weight is to be employed. (The Edinburgh process is the same, except that f℥iij of Rectified Spirit is also used.) Or, Oil of Spearmint fʒij; Powdered Flint ʒij; Distilled Water Cong. j. First diligently rub the oil with the flint, afterwards with the water, and strain the liquor, L.—Essence of Spearmint f℥j; Distilled Water Cong. ss. Mix with agitation, and filter through paper, D.)—Spearmint water is usually made extemporaneously by suspending or dissolving a drachm of the oil in four pints of distilled water, by means of a drachm of rectified spirit and a lump of sugar [or by means of carbonate of magnesia, U. S.] (see vol. i. p. 304). Spearmint water is carminative and stomachic. It is commonly used as a vehicle for other medicines. Its dose is f℥j to f℥iij.