Tea Tree (Melaleuca Alterifolia) – this potent antimicrobial oil is often used to treat acne, burns, inflammation and fungal infections. Tea tree oil can open clogged pores and kill bacteria, while its antioxidant effect reduces free radicals while encouraging the production of collagen. Tea tree oil can also reduce allergic skin reactions. Native to eastern Australia, tea tree leaves were crushed so the oil could be inhaled as a treatment for colds and coughs. Soaked leaves were also used to make an infusion, while a poultice was laid on top of crushed leaves sprinkled over wounds.