Gastrodia

Gastrodia elata is a perennial orchid that has no green leaves and feeds on a fungus, a habit called mycoheterotrophy. It grows in symbiosis with the honey fungus Armillaria mellea on rotting wood, and depends on the fungal threads invading its roots to take up nutrients. It is found from Nepal, Bhutan and India through Siberia, Korea, Japan and Taiwan to China, at the edge of forests between 400 and 3,200 metres. The stem is erect, 0.3 to 1 metre tall and leafless, and an elliptical underground rhizome 8 to 12 centimetres long holds the plant. The rhizome is used in traditional Chinese medicine and Sichuan cuisine as tian-ma, for calming the liver and for headaches, dizziness, tetanus and epilepsy. Its signature compounds are gastrodin and gastrodigenin, and the Chinese Pharmacopoeia sets a minimum content of them.