Also known as the "blue gum" or "Tasmanian Blue", this is the most common eucalyptus species in the world. The tree was originally native to Australia and is now naturalized in many countries including the United States. These leaves are extremely rich in eucalyptol, used in cough medicines, as well as muscle-warming ointments. The eseential oil contains about 70% eucalyptol, making it an effective remedy for chest coughs. The oil has a clean, medicinal and penetrating aroma with fresh notes.