Merriam-Webster Collegiate Dictionary - tea tree

 noun  Etymology: from the use of an infusion of their leaves as a beverage  Date: 1790  1. any of various Australasian shrubs or small trees (genus Leptospermum) of the myrtle family that form dense thickets and have aromatic evergreen foliage  2. any of various melaleucas (especially Melaleuca alternifolia) with aromatic leaves that yield an essential oil used especially as an antiseptic