|Genus:|| Leptospermum |
J.R.Forster & G.Forster
Leptospermum /,- -/ is a genus of shrubs and small trees in the myrtle family Myrtaceae commonly known as tea trees, although this name is sometimes also used for some species of Melaleuca . Most species are endemic to Australia, with the greatest diversity in the south of the continent, but some are native to other parts of the world, including New Zealand and Southeast Asia. Leptospermums all have five conspicuous petals and five groups of stamens which alternate with the petals. There is a single style in the centre of the flower and the fruit is a woody capsule.
The first formal description of a leptospermum was published in 1776 by the German botanists Johann Reinhold Forster and his son Johann Georg Adam Forster, but an unambiguous definition of individual species in the genus was not achieved until 1979. Leptospermums grow in a wide range of habitats but are most commonly found in moist, low-nutrient soils. They have important uses in horticulture, in the production of honey and in floristry.
Plants in the genus Leptospermum range in size from prostrate shrubs to small trees, and have fibrous, flaky or papery bark. The leaves are arranged alternately and are relatively small, rigid and often aromatic when crushed. The flowers may be solitary or in groups, and have bracteoles and sepals which in most species fall off as the flower opens. There are five spreading, conspicuous petals which are white, pink or red. There are many stamens which are usually shorter than the petals and in five groups opposite the stamens, although they often appear not to be grouped. A simple style usually arises from a small depression in the ovary which has from three to five sections in most species, each section containing a few to many ovules. The fruit is a woody capsule which opens at the top to release the seeds, although in some species this does not occur until the plant, or the part of it, dies.
The first formal description of a leptospermum was published by Johann Reinhold Forster and Johann Georg Adam Forster in their 1776 book, Characteres Generum Plantarum.In 1876, George Bentham described twenty species, but noted the difficulty of discriminating between species. ("The species are very difficult to discriminate.") Of the species he named, only ten remain as valid.
In 1979, Barbara Briggs and Laurie Johnson published a classification of the family Myrtaceae in the Journal of the Journal of the Linnean Society of New South Wales . Although there have been revisions to their groupings, their paper allowed a systematic examination of species in the genus Leptospermum.In 1989, Joy Thompson published a complete revision of the genus. In 2000, O'Brien et al. published yet another revision, using matK-based evidence to suggest that Leptospermum is polyphyletic, and should be split into persistent, Western non-persistent, and Eastern non-persistent fruiting plants, with Leptospermum spinescens as an outlier. However, neither phylogeny has been universally accepted. Current estimates recognize about ninety species of Leptospermum.
The common name tea tree derives from the practice of early Australian settlers who soaked the leaves of several species in boiling water to make a herbal tea.
Most Leptospermum species are endemic to Australia where most are found in southern areas of the country. They are most common in moist nutrient-poor soils although they sometimes occupy other situations. Leptospermum laevigatum is usually found growing on beach sand and L. riparium growing in Tasmanian rainforest on the edges of rivers. Leptospermum amboinense extends from Queensland to Southeast Asia and three species, L. javanicum , L. parviflorum and L. recurvum are endemic to southeast Asia. L. recurvum is only found on Mount Kinabalu in Sabah. Leptospermum scoparium is one of the most widespread in the genus and occurs in New South Wales, Victoria, Tasmania and New Zealand, where it is one of the most widespread and important native shrub species.
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 (18 °F) to −10 °C (14 °F); others are sensitive to frost. They tolerate most soils, but many suppliers specify ericaceous (i.e. lime-free) compost 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.
These flowers are also grown in double cultivars and are used in 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.
The nectar from the flowers is harvested by bees; this is used to make Leptospermum honey. Honey produced from Australian Leptospermum polygalifolium , 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. However, after neutralization of this compound, the honey retains bactericidal activity. Methylglyoxal thus does not appear to be the main contributor to the antimicrobial and antibacterial activities.
The nectar of L. scoparium is collected by bees and the honey produced is collected and marketed as Manuka honey.
The following is a list of species accepted by the Australian Plant Census as at March 2020,apart from two species only occurring outside Australia that are accepted by the Royal Botanic Gardens, Kew:
Leptospermum scoparium, commonly called mānuka, manuka, manuka myrtle, New Zealand teatree, broom tea-tree, or just tea tree, is a species of flowering plant in the myrtle family Myrtaceae, native to south-east Australia and New Zealand.
Angophora is a genus of nine species of trees and shrubs in the myrtle family, Myrtaceae and is endemic to eastern Australia. They differ from other eucalypts in having juvenile and adult leaves arranged in opposite pairs, sepals reduced to projections on the edge of the floral cup, four or five overlapping, more or less round petals, and a papery or thin, woody, often strongly ribbed capsule. Species are found between the Atherton Tableland in Queensland and south through New South Wales to eastern Victoria, Australia.
Leucopogon is a genus of about 150-160 species of shrubs or small trees in the family Ericaceae, in the section of that family formerly treated as the separate family Epacridaceae. They are native to Australia, New Zealand, New Caledonia, the western Pacific Islands and Malaysia, with the greatest species diversity in southeastern Australia. Plants in this genus have leaves with a few more or less parallel veins, and tube-shaped flowers usually with a white beard inside.
Prostanthera, commonly known as mintbush or mint bush, is a genus of about 100 species of flowering plants of the Lamiaceae, all of which are endemic to Australia. Plants in the genus Prostanthera are usually shrubs, rarely trees with leaves in opposite pairs, flowers arranged in panicles in leaf axils or on the ends of branchlets, the sepals joined at the base with two lobes, the petals usually blue to purple or white, joined in a tube with two "lips", the lower lip with three lobes and the upper lip with two lobes or notched.
Beyeria is a genus of shrubs and small trees in the family Euphorbiaceae known as turpentine bushes. It was first described as a genus in 1844. The entire genus is endemic to Australia.
Persoonia is a genus of about one hundred species of shrubs and small trees in the subfamily Persoonioideae in the large and diverse plant family Proteaceae. In the eastern states of Australia, they are commonly known as geebungs, while in Western Australia and South Australia they go by the common name snottygobbles. While their flowers are small and not prominent, persoonias are best known in the Australian bush for the striking bright green foliage of many species.
Eriocaulon is a genus of about 400 species commonly known as pipeworts, of monocotyledonous flowering plants in the family Eriocaulaceae. The genus is widely distributed, with the centers of diversity for the group occurring in tropical regions, particularly southern Asia and the Americas. A few species extend to temperate regions, with ca. 10 species in the United States, mostly in the southern states from California to Florida, and only two species in Canada; China has 35 species, also mostly southern. Only one species occurs in Europe, where it is confined to the Atlantic Ocean coasts of Scotland and Ireland; this species also occurs in eastern North America and is thought to be a relatively recent natural colonist in Europe. In the Americas, Eriocaulon is the only genus in its family that occurs north of Florida. They tend to be associated with wet soils, many growing in shallow water, in wetlands, or in wet savannas like flatwoods. In wet soils, their abundance appears to be related to water levels, fire frequency, and competition from other plants such as grasses. Experiments have shown that they are weak competitors compared to many other wetland plant species. Some species can persist as buried seeds during unfavorable conditions. The scientific name is derived from Ancient Greek εριον, erion, meaning 'wool', and καυλός, caulos, meaning 'stalk'.
Kunzea is a genus of plants in the family Myrtaceae and is endemic to Australasia. They are shrubs, sometimes small trees and usually have small, crowded, rather aromatic leaves. The flowers are similar to those of plants in the genus Leptospermum but differ in having stamens that are longer than the petals. Most kunzeas are endemic to Western Australia but a few occur in eastern Australia and a few are found in New Zealand. The taxonomy of the genus is not settled and is complicated by the existence of a number of hybrids.
Homoranthus is a genus of about thirty species of plants in the myrtle family Myrtaceae and all are endemic to Australia. Plants in this genus share similarities with those in both Darwinia and Verticordia. They are shrubs with their leaves arranged in opposite pairs and with flowers appearing either singly or in small groups, usually in upper leaf axils. They are found in Queensland, New South Wales and South Australia. The genus was first described in 1836. None of the species is common nor are they well-known in horticulture.
Ricinocarpos is a plant genus of the family Euphorbiaceae first described as a genus in 1817. The entire genus is endemic to Australia.
Phebalium is a genus of thirty species of shrubs or small trees in the family Rutaceae and is endemic to Australia. The leaves are arranged alternately, simple and often warty, the flowers arranged singly or in umbels on the ends of branchlets or in leaf axils, usually with five sepals, five petals and ten stamens. There are about thirty species and they are found in all Australian states but not in the Northern Territory.
Lepidosperma is a genus of flowering plant of the family Cyperaceae. Most of the species are endemic to Australia, with others native to southern China, southeast Asia, New Guinea, New Caledonia and New Zealand.
Lepyrodia is a plant genus in the family Restionaceae, described as a genus in 1810.
Laxmannia is a genus of tufted perennial herbs in the family Asparagaceae, subfamily Lomandroideae, that are endemic to Australia.
Vittadinia is a genus of Australian and New Zealand plants in the aster tribe within the daisy family.
Leptospermum polygalifolium, commonly known as tantoon, jellybush or yellow tea tree, is a species of shrub or tree of the family Myrtaceae that is endemic to eastern Australia, including Lord Howe Island. It has thin bark, elliptical leaves, white flowers arranged singly on short side shoots and fruit that remain on the plant for a few years.
Leptospermum polygalifolium subsp. montanum known as the mountain tea tree or tantoon is a shrub or small tree found in eastern Australia. The original specimen was collected in 1912 near Yarrowitch. This plant is a sub-species of the Tantoon of the Myrtle family. It resembles other plants commonly referred to as "tea trees" or "paperbarks". The sub-species term montanum refers to its habitat of high altitudes. Polygalifolium is derived from Latin, referring to the resemblance of the leaves to certain members of the Polygala.
Neofabricia is a genus of shrubs and small trees in the family Myrtaceae, first described as a genus in 1788, with the name Fabricia. This, however, was an illegitimate homonym, in other words, someone had already used the name to refer to a very different plant. Therefore, this group in the Myrtaceae was renamed Neofabricia. The entire genus is endemic to Queensland.
Leptospermum madidum is a species of shrub or small tree that is endemic to north-western Australia. It has weeping branches, smooth bark, pale green linear leaves, small white flowers and thin-walled fruit.
Leptospermum polygalifolium subsp. cismontanum, commonly known as tantoon, is a subspecies of flowering plant in the family Myrtaceae and is endemic to near-coastal areas of eastern Australia. It is a shrub or small tree with elliptical leaves and white flowers in spring.
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