What is the origin of Chinese yam?

Chinese yam was originally produced in Jiaozuo, Henan Province, but now it is also produced in Hunan, Hubei, Shanxi, Yunnan, Hebei, Shaanxi, Jiangsu, Zhejiang, Jiangxi, Guizhou, Sichuan, Shandong and other places. The yield of Chinese yam is not large, but the quality is very high. It has a long history and was once a tribute to Qing Dynasty.

Chen Dasou, a great poet of Song Dynasty, wrote such a passage in his "Jade Ting Zan":"There are herbs in the mountains, green as immortal prescription, cut several pieces of jade, pure flower fragrance", referring to the winter good-yam. Twenty miles west of Ruichang City in Jiangxi Province, across the rolling mountain road, bypassing the picturesque Longyuan Reservoir, along the newly built cement township road up the mountain, is Luocheng Mountain, one of the yam bases in Nanyang Township. The parent soil formed by weathering limestone eroded by wind and rain for thousands of years provides special living soil for the growth of Nanyang yam. Nanyang Luocheng Mountain has a long history of planting yam. According to the records of Ruichang County Annals in Longqing Period of Ming Dynasty, Ruichang yam has been cultivated for more than 500 years, and Nanyang Luocheng Mountain was one of the important products and medicinal materials producing areas in Ruichang, Jiangxi Province at that time.

Yam genuine

① The surface of genuine yam is yellow-white or pale yellow, with longitudinal grooves, longitudinal wrinkles and fibrous root marks, occasionally with light brown skin residue. Body weight, solid quality, not easy to break, white powder section, there are small punctate protrusions. Gas micro, taste light, slightly sour, chewy hair sticky.

(2) The starch grains of genuine yam are single flat oval, round, triangular oval or oblong, 8~35μm in diameter, umbilicus dot, herringbone, cross or short slit, with lamellae visible; the multiple grains are rare and consist of 2~3 grains.

(3) The acicular crystal bundle of calcium oxalate existed in the mucus cells of genuine Chinese yam, its length was about 240μm, and the acicular crystal diameter was 2~5μm.

(4) genuine yam has marginal pits, reticulate, thread and annular vessels with diameters of 12~48μm.

Chinese yam counterfeit

① Cassava: often slice shape, skin has been removed, residual skin brown or brown, cut white, pink, near the skin visible obvious vein ring pattern, there is a small wood core in the center, some show cracks, hand touch has talcum powder-like feeling. The smell is slight and the taste is light.

② Ginseng tuber: irregular cylindrical or conical shape, thick residual cork, yellow brown or reddish brown, fresh khaki wood patches (stone cells), easy to peel off. Quality is firm, cross-section is yellowish white, pink sex, have a few light brown punctate thing. No odor, sweet taste, slightly sour, chewy hair sticky.

③ sweet potato: round or irregular thick slices, the remaining skin is thicker reddish or grayish brown. Section white or yellowish white, slightly elastic, visible yellowish brown "tendons" points or lines, near the skin visible a circle of yellowish brown ring. Crispy, powdery, sweet taste.