Iron stick yam is one of the famous specialties in Jiaozuo, Henan Province. It has been planted for three thousand years. It used to be a tribute to the royal family in past dynasties. It belongs to the best yam among the four major Huai medicines (Dioscorea opposita, Rehmannia glutinosa, Achyranthes bidentata and Chrysanthemum). It enjoys a high reputation at home and abroad. Now it has been applied by Jiaozuo City as a national product of origin protection, and the best place of origin is along the Yellow River in wen county, Jiaozuo. This crop has flowed out and was rediscovered in Zhaoguozuo Village, wen county, Jiaozuo. Iron stick yam is rich in protein, vitamins, amino acids and minerals, which can not only nourish the qi of spleen, lung and kidney, but also nourish the yin of spleen, lung and kidney. It is a treasure for nourishing qi and yin. However, the nutritional value and medicinal value of common yam are not as high as that of iron stick yam, and it is only used for cooking.