What it is:
This hurb consistsof the rhizome of Dioscorea opposita Thunb. (family Dio-scoreaceae). The hurb produced in XinxiangPrefecture of HenanProvince isconsidered the best, known as "Huai Yam". It is also produced in Hebei, Shanxi, Shan-dong and some areas in southern and southwestern China. It is harvested in winter,washed clean,skinned, smoked with sulfur, and dried in the sun; or further macerated and rolled into cylindrical rodsand being polished; sliced, unprepared or stir- baked with wheat bran for use.

Property:
Sweet in flavour, neutral in property,acting on the spleen,lung and kidney channels.

Effects:
Reinforcing the spleen and stomach, promoting the production of body fluid tonourish the lung and streng-thening the kidney toarrest spermatorrhea.

Used for:
1. Deficiency ofthe spleen and stomach characterized by poor appetite,lassi-tude or loose stool and diarrhea. It is often used with Ginseng, white atrac-tylodes rhizome and poria, as in Powder of Ginseng, Poria and White Atractylodes (ShenLing Baizhu San).

2. Cough and dyspnea due to lung deficiency. It is often used with dangshen, ophiopogon root, schisandra fruit, etc.

3. Spermatorrhea due to deficiency of the kidney, or leucorrhagia, frequenturination, etc. For spermatorrhea due to deficiency of the kidney, it can be used with prepared rehmannia root and dogwood fruit, as in Bolus of Six Hurbs Including Rehmannia (Liuwei Dihuang Wan); for frequent urination, it can be used with bitter cardamon fruit and lindera root, as in Pill forDecreasing Urination(Suoquan Wan); for profuse leucorrhea due to deficiency of the spleen with the presence of dampness,it is often given together with dang-shen, white atracty-lodes rhizome,plantainseed, etc. ,for yellow leucorrhagia with signs of damp-heat, it should be used with phellodendron bark, etc., for leu-corrhagia due to inconsolidation of the kidney-qi, it can be given along with prepared rehman-nia root, dogwood fruit, dodder seed, etc.

4. Diabetes or consumption of body fluid and yin mani-fested as dysphoria with smothery sensa-tion and thirst. Formild diabetes, it isdecocted as prolonged frequent drinks, 250g everyday, or given together with astra-galus root, pueraria root, trichosanthesroot and anemarrhena rhizome, as in Decoction for Diabetes (Yuye Tang); for thirst due to consumption of body fluid, it can be used with ophiopogon root , fragrant solomonseal rhizome, etc.

Dosage and admi-nistration: 10-30g, big dosage 60-250g, decocted in water for an oral dose; or ground into powder for oral administra-tion, 6-10g each time. It should be used unprepared for nouri-shing yin and promoting the production of body fluid, but stir-baked with wheat bran for invigorating the spleen to stop diarrhea.

Precautions:
It should not be used in cases of abdominal distension due to excessive dampness or food stagnancy.