Laricis Cortex.—Larch-Bark.
Related entry: Larix Americana.—Tamarac
The bark, denuded of its outer corky layer, of Larix europaea, De Candolle (Pinus Larix, Linné; Abies Larix, Lamarck; Larix decidua, Miller).
Nat. Ord.—Coniferae.
COMMON NAMES: European larch-bark, Larch-bark.
ILLUSTRATION: Bentley and Trimen, Med. Plants, 260.
Botanical Source.—The larch is a tree of straight and lofty growth, with wide-spreading branches, whose extremities droop in the most graceful manner. The buds are alternate, perennial, cup-shaped, scaly, producing annually a pencillike tuft of very numerous, spreading, linear, bluntish, entire, smooth, tender, bright-green, deciduous leaves, about an inch long.. The male flowers are drooping, about I inch long, and yellow; the female catkins, erect, larger than the male flowers, variegated with green and pink; the cones are erect, ovate. about an inch long, purple when young, reddish-brown when ripe, their scales spreading, orbicular, slightly reflexed, and cracked at the margin (L.).
History.—The larch inhabits the mountainous regions of central and south Europe, and is cultivated in Europe and America for ornamentation. Venice Turpentine (see Terebinthina Canadensis), is obtained from the trunk. The bark contains a large amount of tannic acid. "A saccharine matter called Manna of Briançon exudes from the branches, and when the larch forests in Russia take fire, a gum issues from the trees during their combustion, which is termed Gummi Orenbergense, and which is wholly soluble in water like gum arabic" (Lindley, Flor. Med., p. 555). The manna referred to contains a peculiar sugar called by Berthelot melezitose.
Description and Chemical Composition.—The bark is the part employed and was official in the British Pharmacopoeia of 1885, as Laricis Cortex, or larch-bark. It is collected from the branches and trunk in the spring of the year. It is of a rose or deep-red color externally (after the corky layer is removed), the internal surface being yellowish or pinkish. The pieces are flat or quilled, and break with a fibrous fracture. It is astringent to the taste, and its odor is somewhat balsamic and terebinthinate. The bark contains gum, sugar, resinous matter, and a peculiar tannin, which strikes olive-green with iron salts. A syrupy preparation, obtained by evaporating an aqueous infusion of larch-bark, yielded to Stenhouse, by cautious distillation, a peculiar volatile body, larixinic acid or larixine (C10H10O5), which exists ready-formed in the bark of larix. It sublimes at 93° C. (199.4° F.). and forms beautiful long, colorless, lustrous crystals, freely soluble in hot water, alcohol, diluted alkalies, or acids, and sparingly so in ether. It has a faintly bitter, aromatic taste, and a feebly empyreumatic or somewhat camphoraceous odor. It is inflammable and is allied to pyrocatechin and pyrogallol, yielding in solution a purple color with ferric chloride. With an excess of concentrated solution of baryta it forms a thick, gelatinous, and transparent precipitate. It occurs most abundantly in the bark of young trees (Amer. Jour. Pharm., 1862, p. 555).
Action, Medical Uses, and Dosage.—(For uses of Venice Turpentine, see Terebinthina Canadensis.) Larch-bark resembles the other terebinthinous barks, and in strong tincture has been used in chronic genito-urinary inflammations, chronic bronchitis to check secretions, and to control the bleeding of purpura hemorrhagica, and in passive hemorrhage. Dose of tincture, 5 to 30 drops.
