tea tree

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A melaleuca tree (Melaleuca alternifolia) of Australia whose leaves yield an oil used in cosmetics and for medicinal purposes.
• noun Any of various evergreen shrubs or small trees of the genus Leptospermum, native to Southeast Asia and Australasia, having showy flowers and small needlelike leaves formerly used to make a tealike beverage.

from The Century Dictionary.

• noun The common tea-plant or tea-shrub. See tea, 2.
• noun A name of various myrtaceous and other plants, chiefly of the genera Leptospermum and Melaleuca, found in Australia, Tasmania, and New Zealand. See phrases below.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The tea plant, Camellia sinensis, from which black, green, oolong and white tea are all obtained.
• noun The tree Melaleuca alternifolia from which tea tree oil is obtained.
• noun A shrub or small tree native to New Zealand and southeast Australia, Leptospermum scoparium.
• noun The kanuka, Kunzea ericoides.
• noun The duke of Argyll's tea tree, Lycium barbarum, also known as wolfberry or matrimony vine.
• noun The shrub ti, Cordyline fruticosa.