The well-known North American species of Dioscorea (Dioscorea villosa), commonly called Wild Yam, is native to the Eastern hardwood forests of the United States and quickly became an important herb to European settlers. There are over 600 species of Dioscorea around the world, many of which are native to the Americas, particularly Central and South America.
I have recently been working on monograph for my up-coming second volume of my book Western Herbs According to Traditional Chinese Medicine: A Practitioners Guide and thought my readers would like to take a peak. Here is a small portion of the monograph.
Moves qi, resolves depression, and relieves pain for liver depression qi stagnation leading to menstrual and abdominal spasms and pain as well as pain do to either cold congealing or wood overacting on earth.
Diffuses and downbears qi, stopping cough and resolving panting, for coughing do to non-diffusion and counter-flow of the lung qi.
There are more than 20 species of dioscorea used in Chinese medicine and a significant number of them, although less well-known in the West, have some similarities with the American species named above. I have translated some information about several of these species to include in the book and thought it would be interesting to some of my readers. I have tried to note those that, along with similar uses, also have similar ecological requirements and morphology.
D. zingiberensis C.H. Wright (火头跟 huǒ tóu gēn), which shares very similar both morphological resemblance and ecological requirements to D. villosa, is found in He Bei, Hu Bei, Hu Nan, Si Chuan, Shanxi, and Gan Su provinces between 100-1500 meters elevation. It is considered bitter, slightly sweet, cool, and with slight toxicity. It clears the lung and stops coughing, disinhibits dampness and frees strangury, and resolves toxin and disperses swelling. It is used to treat lung heat coughing, damp-heat strangury pain, wind-damp lumbus pain, swollen welling-abscess and malign sores, external injuries and sprains, and stings and bites from insects. It is used in decoction 6-15g or is made as a tincture.
D. glabra Roxb. (红山药 hóng shān yào) has as similar morphology and range, but its range pushes more south being found in Guang Dong, Guang Xi, Hai Nan, Gui Zhou, and Yunnan provinces. It resolves toxin and stops dysentery, and quickens the blood and stops bleeding. It is used to treat dysentery, wind-damp impediment pain, lower back taxation detriment, irregular menstruation, flooding and leaking, and external injury with bleeding. It is used in a decoction 9-30g, or as a powder, or as a tincture. Externally it is ground to a powder and applied.
D. esquirolii Prain et Burkill (补血薯 bǔ xuè shǔ) has a very different morphology although it has similar ecological requirements but they are in the southern range latitudginally from D. villosa in Guang Xi, Gui Zhou, and Yunnan from 600-1430 meters elevation. This species is one in the group with divided leaves and grows from a root tuber rather than a rhizome, the later being like D. opposita (山药). It is acrid, slightly sweet, and cool. It cools the blood and stops bleeding, and disperses swelling and stops pain. It is used for postpartum abdominal pain, painful menstruation, pulmonary tuberculosis with coughing of blood, and knocks and falls. It is used in 6-15g dosages in decoction or externally applied as a powder. It is often used alone for the above indications.
D. nipponica Makino (穿山龙 chuān shān lóng) has similar morphology and ecological requirements and latitude growing throughout much of eastern China, although it extends farther north than D. villosa, being found all the way into Russia. The rhizome of this plant is an important source of plant steroids for the drug industry. It is bitter and neutral and enters the liver and lung channels. It dispels wind and expels dampness, quickens the blood, and stops cough. It is used to treat wind-damp impediment pain, numbness and tingling of the limbs, wind-damp-heat, chest impediment heart pain, abdominal pain, chronic bronchitis, knocks and falls, taxation sprains, malaria, swollen welling-abscess, and frost bite. It is decocted either dry (6-9g) or fresh (30-45g) or made into a tincture. Externally it is used fresh pounded and applied or made into a paste. This species appears to be very similar in use to D. villosa.
D. cirrhosa Lour. (薯莨 shǔ liáng) has a different morphology, similar ecological requirements, but grows both within and south of D. villosa’s latitudinal range growing throughout southern China as well as Taiwan, Vietnam, and Thailand. The root is very high in tannin and is used in the fabric industry for dying, which explains part of its use to stop bleeding. It is bitter and cool with small amount of toxicity. It quickens the blood and stops bleeding, rectifies qi and stops pain, and clears heat and resolves toxin. It is used for spitting blood, expectorating blood, vomiting blood, nosebleed, blood in the urine, blood in the stool, flooding and spotting, irregular menstruation, painful menstruation, menstrual block, postpartum abdominal pain, stomach duct and abdominal pain and distention, heat-toxin bloody dysentery, watery diarrhea, joint pain, swelling and pain associated with knocks and falls with or without bleeding, sores and boils, and herpes zoster. It is used as a decoction 3-9g or the squeezed juice or pounded. Externally it is ground to a powder or pounded for application. This species has many similarities to D. villosa but its tannin content makes it a very strong medicinal for stopping bleeding.