There are over seven hundred species of eucalyptus, many of which are used for the production of essential oil. Only a small number are effective for use in aromatherapy. The most famous is Eucalyptus globulus and should not be mixed with Eucalyptus radiata or any other type of eucalyptus essential oil.
Eucalyptus essential oil has a fresh woody, earthy scent, with a strong medicinal aroma and a thin consistency. When used in aromatherapy, it is considered the top note.