164. Melissa Officinalis, Linn.—Common Balm.
Sex. Syst. Didynamia, Gymnospermia.
History.—Both Smith [Florae. Graecae Prodromus, vol. i. p. 423, 1806.] and Sprengel [Hist. Rei Herb. t. i. p. 100.] consider this plant to be the μελισσόφυλλον or μελίτταινα of Dioscorides; [Lib. iii. cap. 118.] but Fraas [Synopsis Plantarum Fl. Classicae, p. 182, 1845.] is of opinion that the Melissa altissima is the species referred to by Dioscorides.
Botany. Gen. Char.— Calyx tubular-campanulate, 13-ribbed, 2-lipped, the upper lip nearly flat, 3-toothed, the inferior lip bifid, the throat naked within. Tube of the corolla recurved-ascending, enlarged from above, naked within, limb 2-lipped, upper lip emarginate erect, lower ones spreading, 3-cleft, the lobes flat, the middle one entire or emarginate. Stamens 4, arched-converging; cells of the anthers at length straggling. Lobes of the style nearly equal, subulate. Nucules dry, smooth (Bentham).
Sp. Char.—Erect, branching. Leaves broad-ovate, crenate, truncate or cordate at the base; the floral ones nearly similar to the cauline ones. Whorls axillary, loose, 1-sided. Bracts (floral leaves) few, ovate. Corolla longer by half than the calyx (Bentham).
Hab.—South of France.
Properties.—The fresh herb (herba melissae) has a strong, peculiar odour, which is somewhat similar to that of lemons. By drying, this is, for the most part, lost. The taste is aromatic, bitter, and somewhat austere. Sesquichloride of iron gives a greenish colour (tannate of iron) to the cold infusion.
Composition.—The principal constituents of balm are volatile oil, resin, bitter matter, gum, tannic acid, and woody fibre. [Pfaff, Mat. Med. Bd. iv. S. 270.]
OIL OF BALM (Oleum Melissa) is pale yellow, and has the peculiar odour of balm. Its sp. gr. is 0.975. Oil of lemon is said to be frequently substituted for it.
Physiological Effects.—The effects of balm are similar to, though milder than, those of the labiate plants already described. The mildness of its operation arises from the small quantity of volatile oil which the plant contains.
Uses.—Balm tea is sometimes employed as a diaphoretic in fevers, as an exhilarating drink in hypochondriasis, and as an emmenagogue in amenorrhoea and chlorosis.