Mythical Herb from Persia. Also the name of a god who ruled over all medicinal herb. The deities made a drink from this herb which cured all diseases and granted the drinker immortality.
Moly
Greek Mythical Herb that enabled the bearer/eater to evade sorceries. Hermes gave it to Odysseus after Circe turned his crew into pigs. It enabled him to avoid her magic and force her to undo her spell.
Panacea
Greek Mythical Herb that could cure any disease. Gives us the modern word -- Panacea
Soma
Vedic Mythical Plant that was a form of the god of the same name. A drink was brewed from this herb. It was intoxicating and granted immortality, visions and great strength to those who drank it. It appears to be similar to Haoma.
Gully Weed
enables user to breathe under water for 1 full hour. You sprout gill when doing this. The taste is horrible and you sometimes need to bring extra because you never know when you might run out of time. This is not the best thing to use but it is very useful in potions.