"Myrtaceas - Examples include cajuput, eucalyptus, niaouli, clove, and tea tree.  The essential oils from this family are contained in cells in the body of the leaf.  They are powerful antiseptics (especially to the respiratory system) as well as being antiviral (See Table 4.6), astringent, stimulant and tonic."

Reference: Shirley Price and Len Price in the book entitled "Aromatherapy for Health Professionals", Harcourt Publishers Limited, London, England, 2000, p. 18.