What it is:
This herb is the root tuber of Knoxia valerianoides Thorel et Pitard (family Euphorbiaceae),mainly produced in the provinces of Shanxi, Shandong, Jiangsu, Sichuan and Guangxi. It is dug out in spring or autumn, washed clean, sliced and dried in sun- light, processed with vinegar for use.

Property:
Bitter in flavour, cold in property, poisonous, acing on the lung, kidney and large intestien channels.

Effects:
Removing water retention, subduing swelling and resolving mass.

Used for:
1. Edema of the face and body, ascites and hydro- thorax. It has a smiliar but less drastic action compared with kansui. It is often used in combination with kansui root and genkwa, as in Ten Jujube Decoction (Shizao Tang) and in Pill for Relieving Ascites (Zhouju Wan).

2. Suppurative infections on the body surface due to noxious heat and scrofula and subcu- taneous nodules due to accumulation of phlegm-fire. It can be used both inter- nally and externally.

Dosage and administration: 1.5- 3g, usually used in pill and powder.

Precautions:
The herb should not be prescribed to preg- nant women and weak patients. It is antagonistic to liquorice.