Does anyone know the reason why 生地黃 is called 地黃 [yellow earth]? I don't know if 六味地黄丸 took the name from 生地黃 or viceversa, but either way I couldn't find neither the etymology of 六味地黄丸 in English (I still can't understand Chinese properly). Any idea for the reason of the presence of 地黄 in the two?
地黄 is the plant, Rehmannia glutinosa. For TCM, it can be used in various ways:
生 (raw) is usually a synonym to 鲜 (fresh), but here also means unprocessed and therefore equivalent to either 鲜 (fresh) or 干 (dry).