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Rhizome Gastrodiae (Tianma)

It is produced in Guizhou, Yunnan, Sichuan, Hebei, Shanxi,Henan, Gansu and Jilin provinces. It used to grow wild, but now the majority is cultivated. The best one is produced in Guizhou province, called “Gui Gastrodiae (Guitianma). Usually it is collected between the Beginning of Winter and early spring. Those collected in winter when the rhizome has not come out are of the best quality, and those collected in spring when the rhizome has come out are inferior to the previous one. After collecting the rhizome is washed clean. With removing the cortex it is soaked in water or alum water to prevent it turning into black. Then it is decocted or steamed for 20-30 minutes till the whitish spots in the cross section disappear. It is spread out and dried at a low temperature (below 60).



It is ellipsoid or slat-shaped, slightly compressed, shrunken and slightly curved.  Those collected in winter have reddish-brown to deep brown dry buds at the top, called “parrot beak”.  Those collected in spring have remains of the stem.  The lower end has a round scar.   The cortex is stripped or partly remains, and the surface is yellowish-white to pale yellowish-brown, with longitudinal wrinkles and many transverse annulations arranged by latent buds. Its texture is hard and does not break easily, and the cross section is fairly even, yellowish-white to brown, horny, translucent. It has a slight odor, and it tastes sweet.   
Wild ones: Externally pale yellowish-brown to grayish-yellow with wrinkles.
Cultivated ones: Externally yellowish-white with fine and delicate corky texture. 
Prepared ones for use: It is an irregular thin slice, yellowish-white or pale brown in color, with longitudinal wrinkles.  The texture is hard and fragile and the cross section is luminous, cuticular and translucent. It has a slight odor and it is tasteless.
Those that are hard and heavy with parrot-beak like buds, luminous cross section and collected in winter are of the best quality, while those that are lighter, hollow with remains of the stem and dull cross section collected in spring are the lower quality ones. 

Quality Classification

In the market it is divided into two categories--those collected in spring and winter.  Each category is further classified into different grades, which vary in price.

Commonly Seen Fake Ones

There are a lot of fake ones in the market.  The commonly seen is the yellow rhizome of Canna Edulis Ker, which is conical with remains of the stem on the top and with frost-like powder. Roller annulations are found.  The texture is hard and its cross section is half cuticular and half starchy. It has a burnt sugar smell, and tastes sweet. It is sticky when you chew it.  Another fake one is the rhizome of Cacalia Davidii (Fr.) H.M. disguised to be Dobinea Delavayi (Baill.) Baill. It has distinct annulations and it is translucent and yellowish-brown in color, and tastes slight sweet. 




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