Leptospermum scoparium, commonly called manuka, New Zealand teatree,broom teatree or just tea tree, is a species of flowering plant in the myrtle family Myrtaceae, native to New Zealand and southeast Australia.It is a prolific scrub-type tree and is often one of the first species to regenerate on cleared land. It is typically a shrub growing to 2–5 m (7–16 ft) tall, but can grow into a moderately sized tree, up to 15 m (49 ft) or so in height. It is evergreen, with dense branching and small leaves 7–20 mm long and 2–6 mm broad, with a short spine tip. The flowers are white, occasionally pink, 8–15 mm (rarely up to 25 mm) in diameter, with five petals.
This species is often confused with the closely related species kanuka – the easiest way to tell the difference between the two species in the field is to feel their foliage – manuka leaves are prickly, while kanuka leaves are soft. The wood is tough and hard.Evidence suggests that L. scoparium originated in Australia before the onset of the Miocene aridity, and dispersed relatively recently from eastern Australia to New Zealand.
It is likely that on arrival in New Zealand, L. scoparium became established in limited edaphically suitable areas until the arrival of Polynesian man, whose fire and forest-clearing brought about the low-nutrient-status soils for which it was preadapted in its homeland. It is now found throughout New Zealand, but is particularly common on the drier east coasts of the North and South Islands, and in Australia in Tasmania, Victoria and New South Wales.
Many more cultivars are available in New Zealand but often the plant performs better in cultivation overseas. This is because in its homeland it is subject to attack by scale insects that secrete a honeydew on which grows a sooty mold that eventually debilitates the plant. Because of this, attempts have been made, with limited commercial success, to cross the showy New Zealand cultivars with mold-resistant Australian Leptospermum species.Scientific studies have shown that tea tree oil made from M. alternifolia may have some promise for mild cases of acne and athlete's foot, however there are many health claims made for it that are not backed by medical evidence.
The oils of Melaleuca can be found in organic solutions of medication that claim to eliminate warts, including the Human papillomavirus. No scientific evidence proves these claims.Melaleuca oils are the active ingredient in Burn-Aid, a popular minor burn first aid treatment (an offshoot of the brandname Band-Aid).
M. leucadendra oil, cajeput tree, is also used in many pet fish remedies such as Melafix and Bettafix to treat bacterial and fungal infections. Bettafix is a lighter dilution of cajeput tree oil, while Melafix is a stronger dilution.
It is most commonly used to promote fin and tissue regrowth. The remedies are often associated with Betta fish (Siamese Fighting Fish) but are also used with other fish.The wood was often used for tool handles. Manuka sawdust imparts a delicious flavour when used for smoking meats and fish. It is cultivated in New Zealand for manuka honey, produced when honeybees gather the nectar from its flowers, and for the pharmaceutical industry. It is also used for carving.