That age-old problem of several plants having the same or similar common names holds true for those species of plants known as “tea tree.” One plant that is sold under the common name Australian tea tree in California is Leptospermum laevigatum. In Australia, this species is also known by the common names Australian myrtle, coast tea tree, and Victorian tea tree. It grows in much of the southern part of Australia (in the states of Victoria, South Australia, and Tasmania) in dry forests along the coast, where it forms dense thickets of twisted, sculptural trunks topped with evergreen foliage. Small white flowers cover the whole tree in the spring. As a garden subject, this Australian tea tree is a tough cookie. It is suitable as a single specimen or planted as a hedge. Ultimate heights of 15 feet or more may be expected, but shearing and pruning can keep it much more manageable. One of its fine qualities for use in our coastal zone is its resistance to salt spray. Plant it right down to the beach and it should thrive.
Leptospermum scoparium is also known as tea tree, tea bush, or manuka by the native New Zealanders. While it grows in southern Australia as well as New Zealand, it was in New Zealand that Captain Cook gave it the name tea tree. He remarked that “the leaves … were used by many of us as tea, which has a very agreeable bitter[ness] and flavor, when they are recent, but loses some of both when they are dried. When the infusion was made strong, it proved emetic to some in the same manner as green tea.” Manuka was used in pre-European times by the traditional people of New Zealand, the Maori, and still is. A decoction of the leaves was drunk for urinary complaints and as a cure for intestinal parasites. The steam from leaves boiled in water was inhaled for head colds. A decoction was prepared from the leaves and bark, and the warm liquid was rubbed on stiff muscles and aching joints. The emollient white gum, called pai manuka, was given to nursing babies and also used to treat scalds and burns. Chewing the bark is said to have a relaxing effect and it enhances sleep.
New Zealand tea tree oil has been on the market since 1993. Most of the material is from the East Cape region of the North Island of New Zealand, although populations from various locations produce potions with discernable chemical differences. The East Cape oil has the strongest antibacterial action. In fact, New Zealand tea tree oil is reported to be as much as 20 times more effective as an antibacterial agent than Australian tea tree oil (see below). Normally growing to 10 feet or less, this shrubby cousin displays some variety in form. Its small flowers may range from cranberry red to pink to white, with double forms also available. Some selections also have bronzy foliage for further interest. It will do best with well-draining soils, but once established should provide lots of good color for much of the year. Its extra gift to the landscaper is that it will flourish in shade.
Melaleuca alternifolia is also from Australia and is also called Australian tea tree. Though tea is in its common name, an infusion of its leaves is a poor substitute for potable tea. And due to some of its chemical components, may even be toxic if consumed in quantity. It is, however, the source of an essential oil that is widely marketed as an antibacterial and skin treatment. This tea tree oil got its name from the British explorers who observed the Aborigines brewing leaves of the tree to make a tea that was used to cure various ailments. For many centuries, the Australian Bundjalung Aborigines bathed in the healing waters of swampy areas where the Melaleuca alternifolia plants grew. They also successfully treated skin conditions by crushing the leaves and spreading the pulp over the affected area.
Another common name for this species is snow in summer (another name applied to more than one species!), which aptly describes the effect of its many bright white bottle-brush-type inflorescences that cover the shrub in summer. It, too, is an evergreen that grows more shrublike than treelike to about 18 feet. Because this tea tree is native to saturated soils, it can take that sort of treatment in the garden, too. It takes poor drainage in stride and hates drought.
As with any plants that have herbal or medicinal properties, grow them for their beauty, but be cautious if you use them for any other purpose.
Virginia Hayes, curator of Ganna Walska Lotusland, will answer your gardening questions. Address them to Gardens, The Independent, 122 W. Figueroa St., S.B., CA 93101. Send email to firstname.lastname@example.org.