Pinellia is a genus of plants in the Araceae family, which includes a wide range of tuber bearing plants, many of which produce oxalic acid crystals in their roots and leaves. Plants in the Pinellia genus are used in traditional Chinese medicine, and some are also planted as ornamentals around the world. Caution should be used when employing Pinellia, also called zhi ban xia or ban xia, in medical treatment, because the roots can be toxic if they are not treated properly. Many Chinese herbalists carry ban xia, in the form of capsules and dried roots for various potential uses.
Plants in this genus tend to have spreading, glossy leaves which may also be colorful, and they grow low to the ground, propagating through tubers. The flowers grow on long stalks, which droop as the seeds ripen. Many ornamental varieties are cultivated for their glossy foliage and simple flowers. The plants are native to China and Japan, where the tubers have been harvested for centuries for use in medicine.
Untreated tubers contain oxalic acid, which can be toxic if consumed. In cases where the Pinellia root will be consumed, it is soaked to remove the oxalic acid, which may be further neutralized with ingredients like tea or vinegar in preparations of the herb. Pinellia is also used for moxibustion, in which case it is not usually specially treated, because the user will not be consuming it. Labeling on Pinellia products is not always reliable; if a package of roots does not specifically state that they are safe for consumption, assume that they need to be treated.
In Traditional Chinese Medicine (TCM), ban xia is used to treat coughing and to encourage the production of phlegm. It is also sometimes used for intestinal complaints such as vomiting or diarrhea. Only small amounts of the herb are used, to avoid a toxic dosage, and since it is classified as a warming and drying herb, it is not suitable for all patients; if a patient is already warm, for example, the herb could exacerbate the condition. Pinellia acts on three meridians: the heart, spleen, and stomach.
The practice of TCM is incredibly complex, and a practitioner requires years of training. The goal of medical treatment is to identify and correct an imbalance, rather than treating the symptoms. Because TCM is complicated, it is a good idea to see a Chinese herbalist before taking Chinese herbs, since he or she may diagnose an imbalance which requires the use of different herbs or supplemental treatments such as acupuncture or moxibustion.