Dioscorea. N. F. IV. Wild Yam Root. Colic-root. Rheumatism-root.—"The dried rhizome of Dioscorea villosa Linne (Fam. Dioscoreaceae)." N. F. IV. An indigenous, perennial, twining plant, with long, knotty, matted, contorted, ligneous root stocks. It grows from Ontario to Wisconsin, and south to Florida and Texas. The rhizome is used by the eclectics, who consider the drugs efficacious in bilious colic, and by the Southern negroes in rheumatism. The rhizome is described by the N. F. as "knotted and woody, elongated, from 6 to 12 mm. in thickness, often compressed, bent and branched, bearing scattered nodular projections at the sides, slender, tough roots underneath and stem-scars on their upper surface; externally pale brown, surface more or less scaly from the partly detached, thin outer layer; fracture short but tough, the fractured surface whitish or pale-brown, with numerous small, scattered, yellowish wood bundles. Odorless; taste starchy, insipid, afterwards acrid. Dioscorea yields not more than 7 per cent. of ash." N. F.
W. C. Kalteyer found abundant saponin in the roots. (A. J. P., 1888; see also M. R., 1913, 311.) A substance, improperly called dioscorein, obtained by precipitating the tincture with water, is used in the dose of from one to four grains (0.0065-0.26 Gm.). Dose, one-half to one drachm (1.9-3.75 mils), which may be given either in the form of a decoction or a fluidextract.
Dioscorea hirsuta, Bl. grows in the island of Java, where it is known as Gadoeng. In 1894 W. G. Boorsma (Mededeelingen wuit's Lands Plantentuin, xiii) separated from it an alkaloid to which he gave the name of dioscorine. This alkaloid has been studied by Plugge and Schutte (A. J. P., iv, 1897) who assigned to it the formula C13H19NO2, and found it to be a convulsant poison, resembling closely in its action picrotoxin, but much more feeble. Dioscorea bulbifera L. grows in the Gaboon country of tropical Africa. Heckel and Schlagdenhauffen found in the tuber a glucoside, together with wax, chlorophyll, saccharose, and resin.
The root of Dioscorea rhipogonoides (?) Oliver, under the names of Cunao, Shu-lang, faux gambier, is exported in enormous quantities from Indo-China to Southern China for use as a dye-stuff.