Rhizoma Dioscoreae Oppositae（山药，（山药，Shanyao）） Common Yanm RhizomeCommon Yanm Rhizome is the dried rhizome of Dioscorea opposita Thunb. (Fam. Dioscoreaceae). The drug is collected in winter when the stem and leaves are withered, cut off, washed clean and peeled outer bark and fibrous roots, and then dried. Alternatively, the large, straight and dried rhizome is sorted, soaked in clean water until no dry core visible and softened thoroughly, cut two ends to smooth plane and rubbed on a board to become cylindrical in shape, dried in the sun, finally polished. It is known as “Guang Shanyao”(Polished Common Yanm Rhizome).Description Subcylindrical, curved or somewhat flattened, 15-30cm long, 1.5-6cm in diameter. Externally yellowish-white or pale yellow, longitudinally furrowed and wrinkled, and bearing fibrous root scars, with occasional patches of brownish cork. Texture heavy, compact and tough; uneasily broken, fracture white and starchy. Odour, slight; taste, weak, acidulous, and viscous on chewing. Guang Shanyao is cylindrical, the two ends even, 9-18cm long, 1.5-3cm diameter, externally smooth, white or yellowish-white. Identification (1)Powder: Whiteish. Simple starch granules compressed-ovoid, deltoid-ovoid, subrounded or oblong, 8-35μｍ in diameter, hilum pointed, V-shaped, crosscriss or shortly cleft, striations visible. Compound starch granules few, usually consisting of 2-3 granules. Mucilage cells containing raphides of calcium oxalate, up to 240μｍ long and needle crystals 2-5μｍ wide. Vessels bordered-pitted, reticulated, spiral and annular, 12-48μｍ in diameter.(2)Heat under reflux 5g of the powder in 30ml of dichloromethane for 2 hours, filter, evaporate the filtrate to dryness, dissolve the residue in 1ml of dichloromethane as the test solution. Heat under reflux 5g of the dioscin in 30ml of dichloromethane for 2 hours, filter, evaporate the filtrate to dryness, dissolve the residue in 1ml of dichloromethane as the reference solution. Carry out the method for thin layer chromatography(Appendix VI B), using silica gel G as the coating substance and mixture of acetidin, methanol and srong ammonia solution (9:1:0.5) as the mobile phase. Apply separately to the plate 4μl of each of the above two solutions. After developing and removal of the plate, dry in air. Spray with 10% solution phosphomolybdic acid in ethanol, and heat to the spots clear. The spot in the chromatogram obtained with the test solution correspond in position colour to the spot in the chromatogram obtained with the reference solution.Checking Water content Not more than 16.0% (Appendix IX H,method 1)Total ash Not more than 4.0%(Appendix IX K)Extractives Carry out the method for determination of water soluble extractive(Appendix X A, the merceration), not less than 7.0%.Decocting piecesProcessing Rhizoma Dioscoreae Oppositae Eliminate foreign matter, grade according to size, soak and soften thoroughly, cut into thick slices,and dry. Subround thick slices, Externally whitish or pale yellowish-white, Texture fragile, easily broken, fracture whitish and starchy. Checking Total ash Not more 2.0%.Extratives Not more than 4.0% The method of Identification、Checking (water content) is same like the method of Rhizoma Dioscoreae Oppositae. Rhizoma Dioscoreae Oppositae (stir-baked with bran) Stir-bake the slives of Rhizoma Dioscoreae Oppositae as described under the method for stir-baking with bran(Appendix Ⅱ D) to yellow.Look like decocting pieces, externally yellowish-white or slightly yellow, with occasional focal spot, odour, scorched. Checking Water content Not more than 12.0% Extratives Not less than 4.0% The method of Identification、Checking (water content) is same like the method of Rhizoma Dioscoreae Oppositae. Action and indications To replenish the spleen and stomach, promote fluid secretion and benefit the lung, and strengthen the kidney and restrain seminal discharge. Anorexia and chronic diarrhea due diminished function of the spleen; cough and dyspnea due to diminished function of the lung; seminal emission, excessive leucorrhea, frequency of urination or diabetes due to deficiency of kidney. Rhizoma Dioscoreae Oppositae (stir-baked with bran) Diminished function of the spleen with anorexia, diarrhea and excessive leucorrhea. Usage and dosage 15-30g Storage Preserve in a ventilated and dry place, protected from moth. 。