The source is from rhizome of Dioscorea Opposite Thunb., family Dioscoreaceae. The medicinal material is produced in Hebei, Shanxi, and Shandong, with the best from Xinxiang county of Henan Province, and harvested in winter and processed in a procedure of washing, peeling, steaming with sulphur, drying, softening and slicing. The crude or stir-baked with bran can be used.

Medicinal Properties: Sweet in flavor, mild in nature, and attributive to the spleen, lung and kidney meridians.

Actions: Invigorate the spleen and stomach; promote production of the body fluids and benefit the lung, invigorate the kidney and preserve the essence.

Application
1. For deficiency of the spleen and stomach with poor appetite, fatigue or loose stools and diarrhea, it is often used together with Renshen ( Radix Ginseng), Baizhu (Rhizoma Atractylodis Macrocephalae ) and Fuling (Poria), etc., such as Shen Ling Baizhu San (Powder).

2. For dyspnea and cough due to deficiency of the lung, it is frequently used together with Dangshen (Radix Codonopsis ), Maimendong ( Radix Ophiopogonis ) and Wuweizi (Fructus Schisandrae), etc.

3. It is applied for kidney-deficiency with emission, frequent micturition or leucorrhagia. In the case of emission due to deficiency of the kidney, it is used together with Shudihuang (Radix Rehmanniae Praeparata ), Shanzhuyu (Fructus Corni), etc., such as Liuwei Dihuang Wan (Pill). For frequent micturition and enuresis, it is used together with Yizhiren (Fructus Alpiniae Oxyphyltae), Wuyao (Radix Linderae), etc., such as Suoquan Wan (Pill). For leucorrhagia due to deficiency of the spleen with dampness, it is usually combined with Dangshen ( Radix Codonopsis ), Baizhu ( Rhizoma Atractytodis Macrocephatae ) , Cheqianzi (Semen Plantaginis); that with damp-heat, used with Huangbai ( Cortex Phellodendri), etc.It should be used together with Shudihuang (Radix Rehmanniae Praeparata ),  Shanzhuyu (Fructus Corni), and Tusizi (Semen Cuscutae), etc., in a case with deficient kidney and inability to preserve the essence.

4. It is applied for diabetes or consumption of the body fluids due to deficiency of yin accompanied by dysphoric fever or thirst. For the light diabetes, it is recommended that 250 g is decocted as a substitute for tea everyday for a long course; or else, to be used together with Huangqi (Radix Astragali), Gegen (Radix Puerariae ), Tianhuafen (Radix Trichosanthis), and Zhimu (Rhizoma Anemarrhenae), etc., such as Yuye Tang (Decoction). For thirst due to consumption of the body fluids, it is used with Maimendong (Radix Ophiopogonis ), Yuzhu ( Rhizoma Polygonati Odorati) , etc..

Usage and Dosage:
15 -30 g or up to 60-250 g is used in decoction; or 6 -10 g of the powder. It's better to use the crude product for the purpose of nourishing yin and promoting the production of the body fluids, and to use the stir-baked one with bran for strengthening the spleen and stopping diarrhea.

Notes:
Contraindicated for the case with excessive dampness in the stomach or with stagnation.