Athelas (S. "Kingsfoil", lit. "Healing-leaf"; Q. asëa aranion) or Kingsfoil was a small, highly enchanted shrub originally native to cool, temperate coniferous forests of Númenor, later widely cultivated throughout the Westlands. A tea brewed from its dark green leaves was potentially capable of curing any disease or injury while the patient was still alive, although it could not keep or give life.
The magic of athelas was highly dependent upon the status of the healer however, only reaching full potency in the hands of an "ordained" king or similar individual. Athelas leaves and fruit were also edible and highly nutritious, and were often believed to have been frequently used in the Elven Waybread (lembas). A plant often called Lesser Kingsfoil or Athelas Minor was the Aelgus, though it was unrelated to true Athelas.