203. Prunus virginiana.—Wild cherry.
Wild cherry bark.
BOTANICAL CHARACTERISTICS.—A large forest tree. Leaves oval-oblong or lance-oblong, brilliant green, smooth on both sides, unequally serrate; flowers white, in racemes; drupes purplish-black and shining; bitter.
SOURCE.—United States and Canada. Although the name Prunus virginiana has been held as the official and medicinal name, the botanical name is P. serotina. This leads to confusion among botanists, who strongly urge the discontinuance of the above official title. Prunus virginiana is the botanical name of the common choke cherry, not of the black wild cherry. Prunus Pennsylvanica, the wild red cherry, growing in rock woods and along the lake shores, is frequently mistaken for the P. serotina.
DESCRIPTION OF DRUG.—About 2 mm. (1/12 in.) or more in thickness, curved or flat. The newer bark is covered with a smooth, greenish periderm, but bark collected from the older parts usually has the corky layer removed, leaving a rough, rust-brown surface, inner surface lighter colored, finely striate; fracture granular. Almost inodorous, but emits the characteristic odor of bitter almonds when moistened; taste astringent, aromatic, and bitter, at the last bitter almond-like.
STRUCTURE.—Beneath the corky layer are found numerous clusters of stone cells, forming an interrupted zone. Just beneath this layer the medullary rays, which in the whole bark are wavy, terminate very obliquely. Between the medullary rays are found masses of stone cells and more elongated bast fibers.
The bark of the root is thought to be the most active, but that of the whole tree is collected indiscriminately.
RELATIVE VALUE OF THE OLD AND NEW BARK.—Experiments by Dohme and by Stevens have been made to decide whether the green bark is richer in hydrocyanic acid than the older, thick, brown bark. The results of the experiments of these gentlemen are somewhat contradictory. Dohme obtains 0.216 and 0.183 per cent. of HCN respectively, while the older bark assays 0.167 and 0.159 per cent. Stevens found in the older bark 0.335 per cent., while the younger assayed only 0.25 per cent. It is probably safe to say that the older thick bark is not so unworthy of recognition as some believe.
Powder.—Characteristic elements: See Part iv, Chap. I, B.
CONSTITUENTS.—Tannin, a bitter glucoside, resin, starch, etc. The volatile oil and hydrocyanic acid, to which the sedative action is due, do not preexist in the bark, but, as in the bitter almond, are formed by the action on amygdalin, in the presence of water, of a ferment analogous to, if not identical with, emulsin; the action of this ferment is destroyed at a boiling temperature, and therefore heat should never be used in making preparations of this bark.
ACTION AND USES.—Tonic and sedative. Owing to the bitter principle it is a stomachic and bitter tonic. Useful in gastric atony and general debility. The syrup forms the basis of many of the cough syrups. Dose: 30 to 60 gr. (2 to 4 Gm.).
Syrupus Pruni Virginianae. Dose: 1 to 4 fl. dr. (4 to 15 mils) .