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Dioscorea (Shuyu)

The flavor is sweet, the nature is warm and neutral, and it is non-toxic. It primarily treats internal injury, tonifies deficiency and emaciation, eliminates pathogenic cold and heat, tonifies the Middle Jiao, benefits Qi and strength, promotes muscle growth, treats wandering wind on the head and face (pathogenic wind that migrates), headache and dizziness, directs Qi downward, and stops lower back pain. It tonifies deficiency and emaciation from chronic fatigue, fills the Zang-Fu organs, eliminates irritability and heat, and strengthens Yin essence. Long-term consumption makes the ears and eyes clear and bright, lightens the body, prevents hunger, and prolongs life. Also known as Shanyu (Mountain Potato), called Yuyan (Jade Delay) in Qin and Chu regions, and Tushu (Earth Yam) in Zheng and Yue regions (pronounced "chu"). It grows in the valleys of Mount Song. The roots are harvested in February and August and dried in the sun. Polyporus (Zizhi) acts as its guide drug, and it is incompatible with Kansui (Gansui).

Tao Hongjing stated: Now it is found everywhere near the capital areas, and many are dug up and eaten in Dongshan and Nanjiang to supplement food supplies. Those produced in Nankang are the largest and finest, and are commonly used for dietary therapy. The *Tang Bencao* commentary notes: Dioscorea, when dried in the sun, pounded fine, and sifted into powder, tastes extremely delicious when eaten and also cures diseases and tonifies the body. There are two types: one is white and superior; the other is greenish-black and less tasty. Those from the Shu road are particularly good. Ministers Yu Xi et al. carefully followed Wu's statement: Dioscorea, also known as Zhushu, called Shan Yang (Mountain Goat) in Qi and Yue regions, also known as Xiu Cui, and Er Cao. Shen Nong considered it: sweet in flavor, slightly warm. Tong Jun and Lei Gong considered it: sweet in flavor, non-toxic. Some grow at Zhongshan in Linqu; when first sprouting, they have red stems and thin vines, bloom white flowers in May, bear greenish-yellow fruits in July, which fall ripe in August, with white interiors and yellow skins in the root, resembling taro. *Yaoxing Lun* states: Dioscorea, used by ministers. It can tonify the five labors and seven injuries, remove cold wind, stop lower back pain, calm the spirit, stabilize the soul, open the heart orifices, improve memory, tonify insufficient Heart Qi, and should be added for patients with deficiency and emaciation. *Yi Yuan* states: Dioscorea, referred to as Tushu by wild people. If one wishes to dig it up, doing so silently yields results, but calling out its name makes it disappear. If someone plants it, it mimics the shape of whatever plant it is grown with. Ri Huazi stated: It assists the five Zang organs, strengthens sinews and bones, enhances willpower, calms the spirit, treats seminal emission, and forgetfulness. Dried ones have the same efficacy.

*Tujing* states: Dioscorea grows in the valleys of Mount Song, and now exists everywhere, with those from Beidu and Siming being superior. Sprouts emerge in spring, climbing and spreading over fences. The stems are purple, leaves green with three pointed angles resembling morning glory but denser and glossier. Small white flowers bloom in summer, similar to jujube flowers. Bell-shaped fruits appear among leaves in autumn. Roots are harvested in February and August, though nowadays people harvest them in winter and spring. Those scraped to reveal white flesh are superior grade; greenish-black ones are inferior. They are dried for use. Processing method: select thick roots, scrape off yellow skin, soak in water with a small amount of alum powder added, leave overnight, take out, wash clean to remove slime, and bake dry. People near the capital cultivate it very successfully. In spring, take old root heads, mix with yellow sand and cow dung to make beds for planting. When shoots emerge, use bamboo tips as supports, not exceeding one or two feet high, irrigate frequently in summer. Edible in the same year, extremely fat and delicious. In the south, there is a type growing in mountains, with roots thin as fingers, very compact. After scraping and boiling in soup, it forms chunks that do not disperse, tasting even more exquisite. It is said to be more beneficial than cultivated garden varieties. Another type appears in Jianghu and Minzhong, with roots like ginger or taro but with purple skin. Some are very large, weighing over a jin each. Scraped and boiled/eaten, they are delicious, though their nature is colder than northern varieties. Locals call it simply Shu (pronounced "shu") or Shanshu. *Shan Hai Jing* says: Looking north from Jing Mountain to Shaoze, the grass there is mostly Shu (pronounced same as Shuyu). Guo Pu commented: Root resembles taro, edible. Nowadays, people in Jiangnan call it simply Shu (pronounced "chu"), likely due to variations in pronunciation weight. Based on this commentary, Shuyu and Shu are the same species. Differences in production between north and south may cause morphological differences. However, the different pronunciations "shu" and "chu" are likely errors passed down through transmission. Also known as Shanyu.

*Dietary Therapy*: Treats headaches, benefits men, aids male sexual potency. Mixed with flour to make cakes, it may slightly move Qi because it cannot counteract the toxicity of flour. Cooked mixed with honey, or decocted in soup, or made into powder, all are excellent. Dried for medicinal use is even better. Lei Gong said: Generally, do not use those grown in flat fields for only two or three decades; choose those grown for ten decades, emerging from mountains, with red skin and whiskers on all sides, which is ideal. If harvested, use a copper knife to peel off the red skin, wash away slime, and steam before use. *Shenghui Fang*: Tonifies deficiency and damage, improves complexion. Grind Dioscorea finely in a mortar, then place in a pot. First fry one large spoonful of butter until fragrant, then gradually add one cup of wine and decoct, stirring evenly. Drink on an empty stomach. *Shiyi Xinjing* treats deficiency-cold of the Lower Jiao, frequent urination, emaciation, and weakness. Use half a jin of raw Dioscorea. Peel, chop finely, grind until smooth. Place in a pan with wine. When wine boils, add Dioscorea. Do not stir. Once cooked, add a little salt and scallion whites, adjust with more wine if needed. Drink three or two cups on an empty stomach; excellent.

*Yanyi* states: Shanyao (Chinese Yam). According to *Bencao*, the first character offended the taboo of Emperor Ying's temple name. The second character is 'Yu'. Tang Daizong's personal name was 'Yu', so the second character was changed to 'Yao'. Thus, people now call it Shanyao. This completely loses the original name. Fearing that over time people might consider Shanyao a different substance, I record this. This substance is valued when dried fresh for medicinal use. Its method: In winter, wrap hands in cloth, use a bamboo knife to scrape off the skin, place in a bamboo sieve under the eaves in a windy spot, avoiding direct sunlight. It dries five parts after one night; wait until fully dry to store. Only strong wind speeds up drying. The reason for using dried form is that fresh and wet forms are slippery and unsuitable for medicine. Cooked forms are only suitable for eating and may stagnate Qi. The rest follows the *Classic*.