Indigenous Australians use the twigs and leaves of the melaleuca (tea tree) medicinally, and science has confirmed the tree's antimicrobial, antifungal, and antiviral properties. Tea tree oil is used topically to treat a range of skin infections, cuts, burns, insect bites and stings. A 2012 review by the National Institutes of Health found that "a 5% tea tree oil gel appears to be as effective as 5% benzoyl peroxide" for treating mild to moderate acne.
(Podcast: The Plant Detective, 8/23/14)