Leptospermum // is a genus of about 80-86 species of plants in the myrtle family Myrtaceae. Most species are endemic to Australia, with the greatest diversity in the south of the continent; but one species extends to New Zealand, another to Malaysia, and L. recurvum is endemic to Malaysia.
They are shrubs or occasionally small trees, reaching 1–8 m (3–26 ft) tall, rarely up to 20 m (66 ft), with dense branching. The leaves are evergreen, alternate, simple, sharp-tipped, and small, in most species not over 1 cm long. The flowers are up to 3 cm diameter, with five white, pink or red petals.
The common name of tea tree used for some species of Leptospermum derives from the practice of early Australian settlers who soaked the leaves of several species in boiling water to make an herbal tea rich in ascorbic acid (Vitamin C). It is said that Captain Cook brewed tea of Leptospermum leaves to prevent scurvy amongst his crews.
The nectar from the flowers is harvested by bees; this is used to make Leptospermum honey. Active honey has strong antibacterial and antifungal properties, this honey has been shown to come from six Leptospermum species growing in Australia and only one species from New Zealand (they refer to the New Zealand honey made from this species as Manuka). Honey produced from Australian Leptospermum polygalifolium, is also known as jelly bush or the lemon-scented tea tree, has been found to contain up to 1750 mg/kg of 'methylglyoxal', (MGO) an antibacterial compound, making it the most potent antimicrobial honey.
In Australia, Leptospermum species are sometimes used as food plants by the larvae of hepialid moths of the genus Aenetus, including A. lewinii and A. ligniveren. These burrow horizontally into the trunk then vertically down.
Most Leptospermum species make desirable garden plants. The hardiest species (L. lanigerum, L. liversidgei, L. polygalifolium, L. rupestre, L. scoparium) are hardy to about −8°C to −10°C; others are sensitive to frost. They tolerate most soils and exposures with good drainage and full sun. Established plants are drought tolerant. They are often found as hedge plants on the west coast of the United States, and some species are popular for cultivation as bonsai. Many cultivars exist.
General Use These flowers are also grown in double cultivars and they look great in all floral designs. However, they do not last when out of water and the single flowers do not last when wired. The 'Pacific Beauty' ( Leptospermum poolgalifolium) is a useful flower to use in large church-service bowls and function arrangements, however use of Leptospermum in corporate designs is less desirable as they dry and drop when subjected to heating and air-conditioning.
- Sunset Western Garden Book, 1995:606–607
- Native honey a sweet antibacterial, Australian Geographic, March 3, 2011.
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