Botanical name: Achyranthis bidentata
Common name: Achyranthis root
Literal name translation: ox knee
Family: Amaranthaceae, amaranth family
Part used in Chinese medicine: root
Major Chinese medicine actions:
Invigorates blood, dispels stasis, tonifes Kidneys and Liver,
strengthens sinews and bones, clears damp-heat in lower burner
Photo Credits: (top to bottom)
Photo 1: Achyranthes bidentata, author Stanislav Doronenko; permission under GFDL
Photo 2: Achyranthes bidentata; author Stanislov Doronenko; permission under GFDL
Achyranthes bidentata grows wild in some area of China, and is considered a weed in the southern United States and other subtropical regions of the world. The Chinese name “Niu Xi” means “ox-knee”, and refers to the swollen leaf nodes on the stems of the plant which resemble the knees of an ox.
There are two major species used for this herb. Achryanthes bidentata is primarily grown in the Huai river basin in Henan and is therefore called Huai Niu Xi. The other species is Cyanthula officinalis and is called Chuan Niu Xi as it is grown in Sichuan. The two herbs have slightly different medicinal functions, though Huai Niu Xi is generally considered superior. When only “Niu Xi” is indicated, it refers to Huai Niu Xi.
Growing and Propagation
With deep, rich, sandy soil and a warm location, this perennial plant grows quickly and vigorously to a height of about 15-18 inches, and is hardy to about 10 degrees F. It prefers an acidic environment and does not do well in clay or alkaline soil. Propagation is easy to achieve by seed planted in late spring. In traditional practice, better quality root growth is stimulated by removing the lower leaves and stems from the first eight inches of the plants main stalk.
Harvesting and Preparation
For medicinal use, the roots should be harvested in the fall after the leaves have shriveled, and after the first or second year of growth. The longest roots are considered the best quality. Normal market quality roots generally measure about 6-20 inches, but those of superior quality can be longer that 5 feet. The plant should be dug up carefully keeping the whole root intact, and then the smaller lateral roots removed. The large roots are tied into bundles and dried in the sun until the outside layer is wrinkled.
Good quality Huai Niu Xi consists of roots that are long and fleshy with a sweet taste. When dried, the roots should be yellowish gray in color, with their crowns cut off.