Xu Duan (Top 4 from Sichuan, Bottom 3 from Hanzhong) (Cylindrical and flattened, greyish-brown, with longitudinal striations)

Hankou Xu Duan Slices

Sichuan Xu Duan Slices

Han Xu Duan

【Naming】

Xu Duan

 【Source】

Shen Nong’s Herbal Classic, Superior Class

 【Common Usage Level】

B

 【Botanical Origin】

Root of Dipsacus asper Wall. or Dipsacus japonicus Miq. of the Dipsacaceae family.

 【Characteristics】

It is long cylindrical or slightly curved, 7~10 cm long, and 1~1.5 cm in diameter. The surface is greyish-brown with twisted longitudinal wrinkles and shallow grooves. Lenticels are transversely cracked, and there are a few root scars. The texture is soft and not easy to break.
The prepared slices are thin slices cut longitudinally or transversely, about 1~3 mm thick, with irregular edges. The cut surface has irregular brownish-black rings, separating the bark and the wood. The bark is dark brown, and the wood is light brown, with whitish markings. The width of the bark is about half that of the wood. The vascular bundles are arranged radially and are slightly dark green. It has a slightly fragrant smell, and a bitter-sweet and astringent taste.

 【Preparation】

1. Raw Xu Duan 2. Stir-fried Xu Duan 3. Wine-processed Xu Duan 4. Salt-processed Xu Duan.

 【Identification】

《Zheng Lei Ben Cao》: “The genuine one is segmented, with yellowish and wrinkled skin”. 《Ben Cao Gang Mu》: “The good one is red and thin, and produces smoke and dust when broken”. 《Ben Cao Gang Mu》: “[Hong Jing said] Light and thin, with a deep color, is superior”, “[Song said] The ones from Sichuan with thick flesh and deep color are the best”, “The ones with tight skin, two or three tenths of an inch thick, and bright yellow, are superior”. 《Ben Cao Bei Yao》: “The product from Sichuan is good, shaped like chicken feet, with yellowish and wrinkled skin, and segmented, is genuine”. 《Pao Zhi Quan Shu》: “What people use today, coming from Zhou, is red and thin, and produces smoke and dust when broken, is good”. 《Ben Cao Qiu Zhen》: “The product from Sichuan is good”. The best ones are thick, firm, easy to break, yellowish-brown on the outside, and greyish-green on the inside.

 【Identification Terminology】

1. Zheng Ti (正提): The third grade specification of Xu Duan medicinal material product. The root strips are completely dry, orchid-green, and as thick as a small finger.
2. Zheng Duan (正斷): The first grade specification of Xu Duan medicinal material product. The root strips are completely dry, plump, soft, emerald green, and as thick as a thumb.
3. Dou Qing Cha (豆青碴): Xu Duan becomes hard after being stored for a long time, is easy to break, the fracture surface is uneven, the outer edge of the bark is brown, and the inside is dark green, called Dou Qing Cha (bean green residue).
4. Mian Duan (副斷) (Fu Duan): The second grade specification of Xu Duan medicinal material product. The root strips are completely dry, soft, emerald green, and as thick as a middle finger. Also known as “Fu Duan (副斷)”.
5. Fu Ti (副提): The third grade specification of Xu Duan medicinal material product. The root strips are completely dry, orchid-green, and as thick as a cigarette.

 【Category】

Root