Gastrodia

Recurrent dizziness with a throbbing or tight headache, irritability, a red face and a wiry pulse, often in someone with raised blood pressure

Heavy, muzzy dizziness with nausea, a thick greasy tongue coating and a slippery pulse, the phlegm picture, where it is paired with ban xia and bai zhu

Migraine that returns with stress or the menstrual cycle in a person whose neck and jaw are held tight

Overview. Tian ma is the dried tuber of a leafless, chlorophyll-free orchid that lives entirely on the fungus Armillaria mellea, so it can only be grown by cultivating the fungus alongside it. It comes from mountain forests of Yunnan, Sichuan, Guizhou, Shaanxi and Hubei, with Yunnan material (Zhaotong) the most prized. The tuber is steamed, dried and sliced; good pieces are translucent, yellowish and horn-like with a parrot-beak bud scar at one end. In Chinese medicine it is the principal herb for internal wind, used for dizziness, headache, convulsions and numbness across two thousand years of records.

Clinical Notes. Reach for tian ma when the complaint is dizziness, headache or tremor and the tongue and pulse suggest that wind is moving in the Liver channel. It is unusually flexible: neutral and sweet, so it fits both the red-faced hypertensive with rising yang (Tian Ma Gou Teng Yin, with gou teng, shi jue ming, du zhong and huang qin) and the pale, tired patient whose dizziness comes from phlegm and Spleen weakness (Ban Xia Bai Zhu Tian Ma Tang).

Chinese Medicine Profile. Temperature: neutral. Taste: sweet. Channels: Liver. Actions: Extinguishes internal wind and stops spasms and tremor; Calms and anchors ascendant Liver yang; Dispels wind and unblocks the collaterals; Relieves headache and dizziness of both excess and deficiency type.

Conservation. Wild populations have been severely overharvested and the species, like all orchids, is listed on CITES Appendix II; all commercial supply should be cultivated (grown with its Armillaria symbiont).