What is "gastrodia"

Gastrodia is a genus of achlorophyllous orchid with 61 currently accepted species (as of June 2014). They are native to Asia ( China, the Russian Far East, Japan, Korea, Southeast Asia, the Indian Subcontinent), Australia, New Zealand, central Africa, and various islands of the Indian and Pacific Oceans.

Gastrodia elata is a traditional Chinese herb, Tian Ma ， and is commonly used in China to treat hypertension, improve circulation and resolve headaches.