Athelas, also known as Kingsfoil, is a plant from Middle-earth and the Lord of the Rings continuum that has minor curative properties which are much stronger when used by a king.
It also acts as a cure for the Black Breath.
Due to the actions of PPC Bioengineering Inc, athelas has become a "secret ingredient" in many Real World medicines.
In Badfic
In badfic, Athelas is the only medical herb in Middle-earth and is the go-to cure for everything. It may also be used for other purposes, such as cooking.