Araceae
Pinellia ternata
Ban xia · Crow-dipper
- Part used
- tuber
- Native range
- China, Japan and Korea; a serious agricultural weed where introduced
- Morphology
- A small aroid to about thirty centimetres with three-parted leaves and a slender green hooded spathe, over a small round tuber.
What is in it
Evidence
No adequate controlled evidence. Appears in widely used classical formulas.
Safety
Raw tuber causes severe irritation of the mouth and throat from calcium oxalate needles, with swelling that can compromise the airway, and gastrointestinal injury if swallowed. The traditional processing with ginger and alum reduces this substantially and is not optional. Contraindicated in pregnancy in classical practice.
Interactions: Classically incompatible with aconite in the eighteen antagonisms
Regulatory: Restricted to processed forms; unprocessed tuber is not permitted.
How the traditions classify it
Three systems, rating the same plant. Where they disagree, none of them is correcting the others — they are separate frameworks that arrived at their categories independently.
Historical use
In the Shennong Bencao Jing, and one of the most frequently used herbs in the materia medica despite its acknowledged toxicity, always in processed form.
Recorded as history and attributed where possible. Long use establishes that a plant was widely used, not that it worked, and not that it was safe.
Worth knowing
Pinellia is the second entry here, after aconite, where the tradition's processing instructions are the safety mechanism, and it works by a completely different route.
The hazard is mechanical rather than chemical. The tuber is packed with raphides — needle-like crystals of calcium oxalate — which are fired into soft tissue on contact and cause immediate burning and swelling. The same defence makes raw taro and dieffenbachia dangerous. Processing with ginger, alum or lime degrades them.
It also belongs to the eighteen antagonisms, a classical list of herb pairs held never to be combined. Whether that list encodes real pharmacological incompatibilities or ritual caution is genuinely argued about, and it is one of the more interesting untested questions in the tradition.
Nomenclature verified against GBIF backbone taxonomy.