What is a yam?

Chinese Materia Medica is the herbal medicine contained in "Chinese Materia Medica", also known as Dioscorea zingiberensis, Dioscorea opposita, Huai Shan, White Yam, etc., the medicinal source is the dried rhizome of Dioscorea zingiberensis, which is the best produced by Huaiqing (now Boai, Wuyi and Wenxian). Huaiyao was exhibited at the Panama World Exposition in 1914, so it is famous both at home and abroad. Over the years, it has exported to more than a dozen countries and regions, including Britain and the United States.

The tuber of Chinese yam is long cylindrical, growing vertically, up to more than 1 meter long, and the cross section is white when dry. Stems usually purplish red, dextral, glabrous. Leaves simple, alternate in lower part of stem, opposite above middle, rarely in whorls of 3, leaf blade variable, ovate-triangular to broadly ovate or hastate. Dioecious, male inflorescences are spikes, female inflorescences are spikes. Capsule not reflexed, trigonous oblate or oblate, seeds inserted in the middle of each loculum, flowering from June to September, fruiting from July to November.

The tuber began to germinate at 100 ℃, the suitable temperature for stem and leaf growth was 25-28 ℃, and the suitable ground temperature for tuber growth was 20-24 ℃. The leaves and vines withered due to frost, and the tuber could withstand the low temperature of-15 ℃. Short-day irradiation can promote the formation of tubers and residual seeds. The requirement of soil is not strict, but the sandy loam with loose soil fertility and strong water holding capacity is the best, the groundwater level is below 1 meter, and the pH of soil is between 6.0 and 8.0.

As a traditional Chinese medicine for both medicine and food, Chinese yam has different producing areas affected by regional climatic characteristics, geological characteristics, growth habits and other factors. Shanxi, Shaanxi, Shandong, Hebei, Zhejiang, Hunan, Sichuan, Yunnan, Guizhou and Guangxi are also cultivated in Shanxi, Shaanxi, Shandong, Hebei, Zhejiang, Hunan, Sichuan, Yunnan, Guizhou and Guangxi. Several major producing areas in Guangxi, Hebei and Henan constitute the main Chinese yam cultivation areas.

Chinese yam is one of the earliest plants eaten by human beings. as early as in the poems of du Fu, the poet of the Tang Dynasty, there is a famous sentence of "intestinal-filled Dioscorea zingiberensis". The tuber is thick, juicy, sweet and sticky, and eating raw and hot food is delicious. The average content of crude protein, crude fiber, starch, sugar, potassium, phosphorus, calcium, magnesium and ash were 14.48%, 3.48%, 43.7%, 1.14%, 2.62%, 0.2%, 0.2%, 0.14% and 5.51%, respectively. There are 16 kinds of yam among the 18 kinds of amino acids needed by human beings.

The sticky substance of Chinese yam is a mucin formed by the combination of mannan and globulin, which can nourish and strengthen, aid digestion, accumulate deficiency sweat, stop diarrhea, mainly treat diarrhea due to spleen deficiency, cough due to lung deficiency, diabetes, chronic enteritis with dyspepsia, etc., which is the most suitable to be taken with Ganoderma lucidum. It has a bright future in the food industry and processing industry.