Aromadendron Andrews ex Steud. Eucalypton St.-Lag. Eudesmia R.Br. Symphyomyrtus Schauer[1]

Eucalyptus (pronounced /ˌjuːkəˈlɪptəs/[2] ) is a diverse genus In biology, a genus is a low-level taxonomic rank (a taxon) used in the classification of living and fossil organisms, which is an example of definition by genus and differentia. The term comes from Latin genus "descent, family, type, gender", cognate with Greek: γένος – genos, "race, stock, kin" of flowering The flowering plants , also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Together with gymnosperms, they are the only extant groups of seed-producing plants, but they can be distinguished from the gymnosperms by a series of synapomorphies (derived characteristics). These characteristics include flowers, trees A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to 6 m; some authors set a minimum of 10 cm trunk diameter (and a few shrubs) in the myrtle Myrtus is a genus of one or two species of flowering plants in the family Myrtaceae, native to southern Europe and north Africa. The plant is an evergreen shrub or small tree, growing to 5 m tall. The leaf is entire, 3-5 cm long, with a fragrant essential oil. The star-like flower has five petals and sepals, and numerous stamens. Petals usually family, Myrtaceae The Myrtaceae or Myrtle family are a family of dicotyledon plants, placed within the order Myrtales. Myrtle, clove, guava, feijoa, allspice, and eucalyptus belong here. All species are woody, with essential oils, and flower parts in multiples of four or five. One notable character of the family is that the phloem is located on both sides of the. Members of the genus dominate the tree flora of Australia For at least 40,000 years before European settlement in the late 18th century, Australia was inhabited by indigenous Australians, who belonged to one or more of the roughly 250 language groups. After sporadic visits by fishermen from the immediate north and discovery by Dutch explorers in 1606, Australia's eastern half was claimed by the British. There are more than 700 species of Eucalyptus, mostly native to Australia, and a very small number are found in adjacent areas of New Guinea New Guinea, the largest island in the Indonesian archipelago, and located in Melanesia immediately north of northeast Australia in the Southwest Pacific, is the world's second largest island with its 786,000 sq km. It has a low population density with its 7.5 million people. Its highest mount is the Puncak Jaya at an elevation of 4,884 m (16,023 and Indonesia Indonesia , officially the Republic of Indonesia (Indonesian: Republik Indonesia), is a country in Southeast Asia and Oceania. Indonesia comprises 17,508 islands. With a population of around 230 million people, it is the world's fourth most populous country, and has the world's largest population of Muslims. Indonesia is a republic, with an and one as far north as the Philippine archipelago The Philippines , officially known as the Republic of the Philippines (Filipino: Republika ng Pilipinas), is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam. The Sulu Sea to the southwest lies between the country and the island of Borneo, and and Taiwan Taiwan, also known as Formosa , is an island situated in East Asia in the Western Pacific Ocean and located off the southeastern coast of mainland China, and comprises most of the territory of the Republic of China (ROC) since the 1950s. The term "Taiwan" has also become a commonly used alternative name both domestically and. Only 15 species occur outside Australia, and only 9 do not occur in Australia. Species of Eucalyptus are cultivated throughout the tropics The tropics is a region of the Earth by the Equator. It is limited in latitude by the Tropic of Cancer in the northern hemisphere at approximately 23°26' N and the Tropic of Capricorn in the southern hemisphere at 23°26' (23.5°) S. The tropics are also referred to as the tropical zone and the torrid zone (see geographical zone) and subtropics The subtropics are the geographical and climatical zone of the Earth immediately north and south of the tropical zone, which is bounded by the Tropic of Cancer and the Tropic of Capricorn, at latitudes 23.5°N and 23.5°S. The term "subtropical" describes the climatic region found adjacent to the tropics, usually between 20 and 40 including the Americas The Americas, or America, are lands in the Western hemisphere, also known as the New World, comprising the continents of North America and South America with their associated islands and regions. America may be ambiguous in English, as it is more commonly used to refer to the United States of America. The Americas cover 8.3% of the Earth's total, Europe Europe is one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally divided from Asia to its east by the water divide of the Ural Mountains, the Ural River, the Caspian Sea, the Caucasus region (Specification of borders) and the Black Sea to the southeast. Europe is bordered by the Arctic Ocean and, Africa Africa is the world's second-largest and second most-populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area. With a billion people (as of 2009, see table) in 61 territories, it accounts for about 14.72% of the world's human population, the Mediterranean Basin The Mediterranean Basin comprises the lands around and surrounded by the Mediterranean Sea. In biogeography, the Mediterranean Basin refers to the lands around the Mediterranean Sea that have a Mediterranean climate, with mild, rainy winters and hot, dry summers, which supports characteristic Mediterranean forests, woodlands, and scrub vegetation, the Middle East The Middle East is a region that encompasses southwestern Asia and Egypt. In some contexts, the term has recently been expanded in usage to sometimes include Afghanistan and Pakistan, the Caucasus and Central Asia, and North Africa. It's often used as a synonym for Near East, in opposition to Far East. The corresponding adjective is Middle-Eastern, China China is seen variously as an ancient civilization extending over a large area in East Asia, a nation and/or a multinational entity and the Indian Subcontinent The Indian subcontinent, also Indian Subcontinent and other terms, is a region of the Asian continent on the Indian tectonic plate south of the Himalayas, forming a land mass which extends southward into the Indian Ocean.

Eucalyptus is one of three similar genera In biology, a genus is a low-level taxonomic rank (a taxon) used in the classification of living and fossil organisms, which is an example of definition by genus and differentia. The term comes from Latin genus "descent, family, type, gender", cognate with Greek: γένος – genos, "race, stock, kin" that are commonly referred to as "eucalypts Eucalypts are woody plants belonging to three closely related genera: Eucalyptus, Corymbia and Angophora," the others being Corymbia Corymbia is a genus of about 113 species of tree that were classified as Eucalyptus species until the mid-1990s. It includes the bloodwoods, ghost gums, spotted gums amongst others. The bloodwoods had been recognised as a distinct group within the large and diverse Eucalyptus genus since 1867. Molecular research in the 1990s, however, showed that and Angophora Angophora is a genus of ten species of trees or large shrubs in the myrtle family , native to eastern Australia. It is closely related to Corymbia and Eucalyptus, and all three are often referred to as "eucalypts". The differences are that Angophora have opposite leaves rather than alternate, and lack a bud cap or operculum. Angophora. Many, but far from all, are known as gum trees because many species exude copious sap Sap is a fluid transported in xylem cells or phloem sieve tube elements of a plant. Fluid found in the vacuoles of other cells is sometimes referred to as "cell sap". Other liquid compounds found in plants or exuded by plants, such as latex, resins or mucilage, are sometimes incorrectly referred to as sap from any break in the bark Bark is the outermost layers of stems and roots of woody plants. Plants with bark include trees, woody vines and shrubs. Bark refers to all the tissues outside of the vascular cambium and is a nontechnical term. It overlays the wood and consists of the inner bark and the outer bark. The inner bark, which in older stems is living tissue, includes (e.g. Scribbly Gum). The generic name is derived from the Greek Greek , an independent branch of the Indo-European family of languages, is the language of the Greeks. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. In its ancient form, it is the language of classical ancient Greek literature and the New Testament of words ευ (eu), meaning "well," and καλυπτος (kalyptos), meaning well "covered," which refers to the operculum on the calyx A sepal is a part of the flower of angiosperms (flowering plants). Sepals in most flowers are green and lie under the more conspicuous petals. However, the term tepal is usually applied when the petals and sepals share the same color, or the petals are absent and the sepals are colorful. When the flower is in bud, the sepals enclose and protect that initially conceals the flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to mediate the union of male sperm with female ovum in order to produce seeds. The process begins with pollination, is followed by fertilization, leading to the formation and dispersal of the seeds. For.[3]

Eucalyptus has attracted attention from global development Development economics is a branch of economics which deals with economic aspects of the development process in low-income countries. Its focus is not only on methods of promoting economic growth and structural change but also on improving the potential for the mass of the population, for example, through health and education and workplace researchers and environmentalists. It is a fast-growing source of wood, its oil Eucalyptus oil is the generic name for distilled oil from the leaf of Eucalyptus, a genus of the plant family Myrtaceae native to Australia and cultivated worldwide. Eucalyptus oil has a history of wide application, as a pharmaceutical, antiseptic, repellent, flavouring, fragrance and industrial uses. The leaves of selected Eucalyptus species are can be used for cleaning and functions as a natural insecticide An insecticide is a pesticide used against insects. They include ovicides and larvicides used against the eggs and larvae of insects respectively. Insecticides are used in agriculture, medicine, industry and the household. The use of insecticides is believed to be one of the major factors behind the increase in agricultural productivity in the 20, and it is sometimes used to drain A swamp is a wetland featuring flooding of large areas of land by shallow bodies of water. A swamp generally has a substantial number of hammocks, or dry-land protrusions, covered by aquatic vegetation, or vegetation that tolerates periodical inundation. The two main types of swamp are "true" or forest swamps and "transitional" swamps A swamp is a wetland featuring flooding of large areas of land by shallow bodies of water. A swamp generally has a substantial number of hammocks, or dry-land protrusions, covered by aquatic vegetation, or vegetation that tolerates periodical inundation. The two main types of swamp are "true" or forest swamps and "transitional" and thereby reduce the risk of malaria Malaria is a mosquito-borne infectious disease caused by a eukaryotic protist of the genus Plasmodium. It is widespread in tropical and subtropical regions, including parts of the Americas , Asia, and Africa. Each year, there are approximately 350–500 million cases of malaria, killing between one and three million people, the majority of whom. Outside their natural ranges, eucalypts are both lauded for their beneficial economic impact on poor populations[4][5]:22 and derided for being invasive "Invasive species", or Invasive Exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions water-suckers,[6] leading to controversy over their total impact.[7]

Contents

Description

Eucalyptus regnans Eucalyptus regnans, known variously by the common names Mountain Ash, Victorian Ash, Swamp Gum, Tasmanian Oak or Stringy Gum, is a species of Eucalyptus native to southeastern Australia, in Tasmania and Victoria. Historically, it has been known to attain heights over 100 metres and is one of the tallest tree species in the world, a forest tree, showing crown dimension, Tasmania Tasmania is an Australian island and state. It is located 240 kilometres south of the continent, from which it is separated by Bass Strait. The state includes the island of Tasmania – the 26th largest island in the world – and the surrounding islands. The state has a population of 500,000 (as of December 2008[update]), of whom almost half, Australia For at least 40,000 years before European settlement in the late 18th century, Australia was inhabited by indigenous Australians, who belonged to one or more of the roughly 250 language groups. After sporadic visits by fishermen from the immediate north and discovery by Dutch explorers in 1606, Australia's eastern half was claimed by the British Eucalyptus camaldulensis The River Red Gum is a tree of the genus Eucalyptus. It is one of around 800 in the genus. It is a plantation species in many parts of the world but is native to Australia where it is widespread especially beside inland water courses. Oddly, it is named for a private estate garden near the Camaldoli monastery near Naples (L'Hortus Camaldulensis di, immature woodland trees, showing collective crown habit, Murray River, Tocumwal Tocumwal is a town in the southern Riverina region of New South Wales, Australia in the Berrigan Shire Local Government Area, near the Victorian border. The town is situated on the banks of the Murray River, 270 kilometres (170 mi) north of the city of Melbourne. The Newell Highway, part of the main road route between Brisbane and Melbourne, New South Wales New South Wales , Australia's most populous state, is located in the south-east of the country, north of Victoria, south of Queensland, east of South Australia and encompasses the whole of the Australian Capital Territory. It was founded in 1788 and originally comprised much of the Australian mainland, as well as Van Diemen's Land, Lord Howe, Australia For at least 40,000 years before European settlement in the late 18th century, Australia was inhabited by indigenous Australians, who belonged to one or more of the roughly 250 language groups. After sporadic visits by fishermen from the immediate north and discovery by Dutch explorers in 1606, Australia's eastern half was claimed by the British Eucalyptus cretata Eucalyptus cretata, Darke Peak Mallee, is a mallee or, rarely, a small tree restricted to the upper Eyre Peninsula in South Australia, particularly near Darke Peak and Carrapee Hill, juvenile, showing low branching ‘mallee’ form, Melbourne The metropolis is located on the large natural bay known as Port Phillip, with the city centre positioned at the estuary of the Yarra River . The metropolitan area then extends south from the city centre, along the eastern and western shorelines of Port Phillip, and expands into the hinterland. The city centre is situated in the municipality known, Victoria, Australia Victoria is the second most populous state in Australia. Geographically the smallest mainland state, Victoria is bordered by New South Wales to the north, South Australia to the west, and Tasmania to the south, across the Bass Strait. Victoria is the most densely populated state, and has a highly centralised population, with over 70% of Victorians Eucalyptus angustissima, showing shrub form, Melbourne The metropolis is located on the large natural bay known as Port Phillip, with the city centre positioned at the estuary of the Yarra River . The metropolitan area then extends south from the city centre, along the eastern and western shorelines of Port Phillip, and expands into the hinterland. The city centre is situated in the municipality known, Victoria, Australia Victoria is the second most populous state in Australia. Geographically the smallest mainland state, Victoria is bordered by New South Wales to the north, South Australia to the west, and Tasmania to the south, across the Bass Strait. Victoria is the most densely populated state, and has a highly centralised population, with over 70% of Victorians Eucalyptus platypus, showing ‘marlock’ form, Melbourne The metropolis is located on the large natural bay known as Port Phillip, with the city centre positioned at the estuary of the Yarra River . The metropolitan area then extends south from the city centre, along the eastern and western shorelines of Port Phillip, and expands into the hinterland. The city centre is situated in the municipality known

Size and habitat

A mature Eucalyptus may take the form of a low shrub or a very large tree. There are three main habit and four size categories that species In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are often used, such as based on similarity of DNA or can be divided into.

As a generalisation "forest A forest is an area with a high density of trees. There are many definitions of a forest, based on the various criteria. These plant communities cover approximately 9.4% of the Earth's surface (or 30% of total land area), though they once covered much more (about 50% of total land area), in many different regions and function as habitats for trees" are single-stemmed and have a crown forming a minor proportion of the whole tree height. "Woodland trees" are single-stemmed although they may branch at a short distance above ground level.

"Mallees" are multi-stemmed from ground level, usually less than 10 m (33 ft) in height, often with the crown predominantly at the ends of the branchlets and individual plants may combine to form either an open or closed formation. Many mallee trees may be so low-growing as to be considered a shrub.

Two other tree forms are notable in Western Australia and described using the native names "mallet" and "marlock". The "mallet" is a small to medium-sized tree that does not produce lignotubers and has a relatively long trunk, a steeply branching habit and often a conspicuously dense terminal crown. This is the normal habit of mature healthy specimens of Eucalyptus occidentalis, E. astringens, E. spathulata, E. gardneri, E. dielsii, E. forrestiana, E. salubris, E. clivicola and E. ornata. The smooth bark of mallets often has a satiny sheen and may be white, cream, grey, green or copper.

The term marlock has been variously used; in Forest Trees of Australia it is defined as a small tree without lignotubers but with a shorter, lower-branching trunk than a mallet. They usually grow in more or less pure stands. Clearly recognisable examples are stands of E. platypus, E. vesiculosa and the unrelated E. stoatei.

The term "morrell" is somewhat obscure in origin and appears to apply to trees of the western Australian wheatbelt and goldfields which have a long, straight trunk, completely rough-barked. It is now used mainly for E. longicornis (Red Morrell) and E. melanoxylon (Black Morrell).

Tree sizes follow the convention of:

Leaves

Nearly all Eucalyptus are evergreen but some tropical species lose their leaves at the end of the dry season. As in other members of the myrtle family, Eucalyptus leaves are covered with oil glands. The copious oils produced are an important feature of the genus. Although mature Eucalyptus trees are usually towering and fully leafed, their shade is characteristically patchy because the leaves usually hang downwards.

Leaf and flowerbud cluster of Eucalyptus angophoroides Eucalyptus tetragona, showing glaucous leaves & stems

The leaves on a mature Eucalyptus plant are commonly lanceolate, petiolate, apparently alternate and waxy or glossy green. In contrast, the leaves of seedlings are often opposite, sessile and glaucous. But there are many exceptions to this pattern. Many species such as E. melanophloia and E. setosa retain the juvenile leaf form even when the plant is reproductively mature. Some species, such as E. macrocarpa, E. rhodantha and E. crucis, are sought-after ornamentals due to this lifelong juvenile leaf form. A few species, such as E. petraea, E. dundasii and E. lansdowneana, have shiny green leaves throughout their life cycle. E. caesia exhibits the opposite pattern of leaf development to most Eucalyptus, with shiny green leaves in the seedling stage and dull, glaucous leaves in mature crowns. The contrast between juvenile and adult leaf phases is valuable in field identification.

Four leaf phases are recognised in the development of a Eucalyptus plant: the ‘seedling’, ‘juvenile’, ‘intermediate’ and ‘adult’ phases. However there is no definite transitional point between the phases. The intermediate phase, when the largest leaves are often formed, links the juvenile and adult phases.[8]

In all except a few species, the leaves form in pairs on opposite sides of a square stem, consecutive pairs being at right angles to each other (decussate). In some narrow-leaved species, for example E. oleosa, the seedling leaves after the second leaf pair are often clustered in a detectable spiral arrangement about a five-sided stem. After the spiral phase, which may last from several to many nodes, the arrangement reverts to decussate by the absorption of some of the leaf-bearing faces of the stem. In those species with opposite adult foliage the leaf pairs, which have been formed opposite at the stem apex, become separated at their bases by unequal elongation of the stem to produce the apparently alternate adult leaves.

Eucalyptus leucoxylon var. ‘Rosea’ showing flowers & buds with operculum present Eucalyptus melliodora, showing flowers and fruit capsules

Flowers

Flower buds and opercula of E. erythrocorys

The most readily recognisable characteristics of Eucalyptus species are the distinctive flowers and fruit (capsules or "gumnuts"). Flowers have numerous fluffy stamens which may be white, cream, yellow, pink or red; in bud, the stamens are enclosed in a cap known as an operculum which is composed of the fused sepals or petals or both. Thus flowers have no petals, but instead decorate themselves with the many showy stamens. As the stamens expand, the operculum is forced off, splitting away from the cup-like base of the flower; this is one of the features that unites the genus. The name Eucalyptus, from the Greek words eu-, well, and kaluptos, cover, meaning "well-covered", describes the operculum. The woody fruits or capsules are roughly cone-shaped and have valves at the end which open to release the seeds. Most species do not flower until adult foliage starts to appear; Eucalyptus cinerea and Eucalyptus perriniana are notable exceptions.

The dark, fissured ‘ironbark’ of Eucalyptus.sideroxylon

Bark

Bark detail of, Eucalyptus angophoroides, Apple Box

The appearance of Eucalyptus bark varies with the age of the plant, the manner of bark shed, the length of the bark fibres, the degree of furrowing, the thickness, the hardness and the colour. All mature eucalypts put on an annual layer of bark, which contributes to the increasing diameter of the stems. In some species, the outermost layer dies and is annually deciduous, either in long strips (as in Eucalyptus sheathiana) or in variably sized flakes (E. diversicolor, E. cosmophylla or E. cladocalyx). These are the gums or smooth-barked species. The gum bark may be dull, shiny or satiny (as in E. ornata) or matte (E. cosmophylla). In many species, the dead bark is retained. Its outermost layer gradually fragments with weathering and sheds without altering the essentially rough-barked nature of the trunks or stems — for example E. marginata, E. jacksonii, E. obliqua and E. porosa.

The extraordinary coloured bark of Eucalyptus deglupta native to South East Asia

Many species are ‘half-barks’ or ‘blackbutts’ in which the dead bark is retained in the lower half of the trunks or stems — for example, E. brachycalyx, E. ochrophloia and E. occidentalis — or only in a thick, black accumulation at the base, as in E. clelandii. In some species in this category, for example E. youngiana and E. viminalis, the rough basal bark is very ribbony at the top, where it gives way to the smooth upper stems. The smooth upper bark of the half-barks and that of the completely smooth-barked trees and mallees can produce remarkable colour and interest, for example E. deglupta.[8]

The box bark of Eucalyptus quadrangulata, or White Box

Bark characteristics

Species and hybridism

There are over 700 species of Eucalyptus; refer to the List of Eucalyptus species for a comprehensive list of species. Some have diverged from the mainstream of the genus to the extent that they are quite isolated genetically and are able to be recognised by only a few relatively invariant characteristics. Most, however, may be regarded as belonging to large or small groups of related species, which are often in geographical contact with each other and between which gene exchange still occurs. In these situations many species appear to grade into one another, and intermediate forms are common. In other words, some species are relatively fixed genetically, as expressed in their morphology, while others have not diverged completely from their nearest relatives.

Hybrid individuals have not always been recognised as such on first collection and some have been named as new species, such as E. chrysantha (E. preissiana × E. sepulcralis) and E. "rivalis" (E. marginata × E. megacarpa). Hybrid combinations are not particularly common in the field, but some other published species frequently seen in Australia have been suggested to be hybrid combinations. For example, E. erythrandra is believed to be E. angulosa × E. teraptera and due to its wide distribution is often referred to in texts.[8]

Related genera

A small genus of similar trees, Angophora, has also been known since the 18th century. In 1995 new evidence, largely genetic, indicated that some prominent Eucalyptus species were actually more closely related to Angophora than to the other eucalypts; they were split off into the new genus Corymbia. Although separate, the three groups are allied and it remains acceptable to refer to the members of all three genera, Angophora, Corymbia and Eucalyptus, as "eucalypts".

Eucalyptus regnans exceeding 80 metres, in an area of extensive logging, Tasmania

Tall timber

Several eucalypts are among the tallest trees in the world. Eucalyptus regnans, the Australian Mountain Ash, is the tallest of all flowering plants (Angiosperms); today, the tallest measured specimen named Centurion is 99.6 m (327 ft) tall.[9] Only Coast Redwood is taller and Coast Douglas-fir about the same; they are conifers (Gymnosperm). Six other eucalypt species exceed 80 metres in height: Eucalyptus obliqua, Eucalyptus delegatensis, Eucalyptus diversicolor, Eucalyptus nitens, Eucalyptus globulus and Eucalyptus viminalis.

Tolerance

Most eucalypts are not tolerant of frost, or only tolerate light frosts down to –3 °C to –5 °C; the hardiest are the so-called Snow Gums, such as Eucalyptus pauciflora which is capable of withstanding cold and frost down to about –20 °C. Two subspecies, E. pauciflora subsp. niphophila and E. pauciflora subsp. debeuzevillei in particular are even hardier and can tolerate even quite severe winters. Several other species, especially from the high plateau and mountains of central Tasmania such as Eucalyptus coccifera, Eucalyptus subcrenulata, and Eucalyptus gunnii, have produced extreme cold-hardy forms and it is seed procured from these genetically hardy strains that are planted for ornament in colder parts of the world.

Animal relationships

Phascolarctos cinereus Koala eating eucalyptus leaves Sawfly larvae feeding on eucalyptus leaves

An essential oil extracted from Eucalyptus leaves contains compounds that are powerful natural disinfectants and can be toxic in large quantities. Several marsupial herbivores, notably koalas and some possums, are relatively tolerant of it. The close correlation of these oils with other more potent toxins called formylated phloroglucinol compounds allows koalas and other marsupial species to make food choices based on the smell of the leaves. For koalas, these compounds are the most important factor in leaf choice.

Eucalyptus flowers produce a great abundance of nectar, providing food for many pollinators including insects, birds, bats and possums. Although Eucalyptus trees are seemingly well-defended from herbivores by the oils and phenolic compounds, they have insect pests. These include the Eucalyptus Longhorn Borer Phoracantha semipunctata and the aphid-like psyllids known as "bell lerps", both of which have become established as pests throughout the world wherever eucalypts are cultivated.

Further information: list of Lepidoptera that feed on Eucalyptus

Fire

On warm days vaporised Eucalyptus oil rises above the bush to create the characteristic distant blue haze of the Australian landscape. Eucalyptus oil is highly flammable (trees have been known to explode[7][10]) and bush fires can travel easily through the oil-rich air of the tree crowns. The dead bark and fallen branches are also flammable. Eucalypts are well adapted for periodic fires via lignotubers and epicormic shoots under the bark.

Eucalyptus forest in a state of regeneration Eucalyptus trees bent over due to the high winds and heat of the October 2007 California Wildfires. They are located in the San Dieguito River Park of San Diego County and leaning west

Eucalypts originated between 35 and 50 million years ago, not long after Australia-New Guinea separated from Gondwana, their rise coinciding with an increase in fossil charcoal deposits (suggesting that fire was a factor even then), but they remained a minor component of the Tertiary rainforest until about 20 million years ago, when the gradual drying of the continent and depletion of soil nutrients led to the development of a more open forest type, predominantly Casuarina and Acacia species. With the arrival of the first humans about 50 thousand years ago, fires became much more frequent and the fire-loving eucalypts soon came to account for roughly 70% of Australian forest.

The two valuable timber trees, Alpine Ash E. delegatensis and Australian Mountain Ash E. regnans, are killed by fire and only regenerate from seed. The same 2003 bushfire that had little impact on forests around Canberra resulted in thousands of hectares of dead ash forests. However, a small amount of ash survived and put out new ash trees as well. There has been some debate as to whether to leave the stands or attempt to harvest the mostly undamaged timber, which is increasingly recognised as a damaging practice.

Cultivation, uses, and environmental effects

Eucalyptus niphophila in Namadgi National Park

Eucalypts have many uses which have made them economically important trees, and have become a cash crop in poor areas such as Timbuktu, Africa[5]:22 and the Peruvian Andes,[4] despite concerns that the trees are invasive in some countries like South Africa.[6] Best-known are perhaps the varieties Karri and Yellow box. Due to their fast growth, the foremost benefit of these trees is their wood. They can be chopped off at the root and grow back again. They provide many desirable characteristics for use as ornament, timber, firewood and pulpwood. Eucalyptus is considered the world’s top quality pulping species due to its high fibre yields. It is also used in a number of industries, from fence posts and charcoal to cellulose extraction for biofuels. Fast growth also makes eucalypts suitable as windbreaks and to reduce erosion.

Eucalypts draw a tremendous amount of water from the soil through the process of transpiration. They have been planted (or re-planted) in some places to lower the water table and reduce soil salination. Eucalypts have also been used as a way of reducing malaria by draining the soil in Algeria, Lebanon, Sicily,[11], elsewhere in Europe, and California.[12] Drainage removes swamps which provide a habitat for mosquito larvae, but can also destroy ecologically productive areas. This drainage is limited to the soil surface only, because the eucalyptus roots have up to 2.5 m (8.2 ft) length, not reaching the phreatic zone; thus rain or irrigation can wet the soil again.

Eucalyptus oil is readily steam distilled from the leaves and can be used for cleaning, deodorising, and in very small quantities in food supplements, especially sweets, cough drops and decongestants. It also has insect repellent properties (Jahn 1991 a, b; 1992), and is an active ingredient in some commercial mosquito repellents (Fradin & Day 2002).[13]

The nectar of some eucalypts produces high-quality monofloral honey. Eucalypt wood is also commonly used to make digeridoos, a traditional Australian Aboriginal wind instrument. The trunk of the tree is hollowed out by termites, and then cut down if the bore of is the correct size and shape.

All parts of Eucalyptus may be used to make dyes that are substantive on protein fibres such as (silk and wool), simply by processing the plant part with water. Colours to be achieved range from yellow and orange through green, tan, chocolate and deep rust red.[14] The material remaining after processing can be safely used as mulch or fertiliser.[citation needed]

Plantation and ecological problems

Eucalyptus was first introduced from Australia to the rest of the world by Sir Joseph Banks, botanist, on the Cook expedition in 1770. It was subsequently introduced to many parts of the world, notably California, Brazil, Ecuador, Colombia, Ethiopia, Morocco, Portugal, South Africa, Uganda, Israel, Galicia and Chile. In Portugal and also Spain, eucalypts have been planted in pulpwood plantations. Eucalyptus are the basis for several industries, such as sawmilling, pulp, charcoal and others. Several species have become invasive and are causing major problems for local ecosystems, mainly due to the absence of wildlife corridors and rotations management.

Due to similar favorable climatic conditions, Eucalyptus plantations have often replaced oak woodlands, for example in California and Portugal. The resulting monocultures have raised concerns about loss of biological diversity, through loss of acorns that mammals and birds feed on, absence of hollows that in oak trees provide shelter and nesting sites for birds and small mammals and for bee colonies, as well as lack of downed trees in managed plantations.

In seasonally dry climates oaks are often fire-resistant, particularly in open grasslands, as a grass fire is insufficient to ignite the scattered trees. In contrast a eucalyptus forest tends to promote fire because of the volatile and highly combustible oils produced by the leaves, as well as the production of large amounts of litter which is high in phenolics, preventing its breakdown by fungi and thus accumulates as large amounts of dry, combustible fuel.[15] Consequently, dense eucalypt plantings may be subject to catastrophic firestorms. Eucalypts obtain their long-term fire survivability from their ability to regenerate from epicormic shoots and lignotubers,[15] or by producing serotinous fruits.

North America

California. In the 1850s, Eucalyptus trees were introduced to California by Australians during the California Gold Rush. Much of California has a similar climate to parts of Australia. By the early 1900s, thousands of acres of eucalypts were planted with the encouragement of the state government. It was hoped that they would provide a renewable source of timber for construction, furniture making and railroad ties. It was soon found that for the latter purpose eucalyptus was particularly unsuitable, as the ties made from eucalyptus had a tendency to twist while drying, and the dried ties were so tough that it was nearly impossible to hammer rail spikes into them.

"They went on to note that the promise of eucalyptus in California was based on the old virgin forests of Australia. This was a mistake as the young trees being harvested in California could not compare in quality to the centuries-old eucalyptus timber of Australia. It reacted differently to harvest. The older trees didn't split or warp as the infant California crop did. There was a vast difference between the two, and this would doom the California eucalyptus industry."[16]

One way in which the eucalyptus, mainly the blue gum E. globulus, proved valuable in California was in providing windbreaks for highways, orange groves, and other farms in the mostly treeless central part of the state. They are also admired as shade and ornamental trees in many cities and gardens.

Eucalyptus forests in California have been criticised because they compete with native plants and do not support native animals. Fire is also a problem. The 1991 Oakland Hills firestorm which destroyed almost 3,000 homes and killed 25 people was partly fueled by large numbers of eucalypts close to the houses.[17]

In some parts of California, eucalypt forests are being removed and native trees and plants restored. Individuals have also illegally destroyed some trees and are suspected of introducing insect pests from Australia which attack the trees.[18]

Eucalyptus trees do exceptionally well in the Pacific Northwest: Washington, Oregon and parts of British Columbia.

South America

Uruguay. Antonio Lussich introduced Eucalyptus into Uruguay in approximately 1896, throughout what is now Maldonado Department, and it has spread all over the south-eastern and eastern coast. There had been no trees in the area because it consisted of dry sand dunes and stones. (Lussich also introduced many other trees, particularly Acacia and Pines, but they have not expanded so massively.)

Brazil. Eucalyptus was introduced to Brazil in 1910, for timber substitution and the charcoal industry. It has thrived in the local environment, and today there are around 5 million hectares planted. The wood is highly appreciated by the charcoal and pulp and paper industries. The short rotation allows a larger wood production and supplies wood for several other activities, helping to preserve the native forests from logging. When well managed, the plantations are sustainable and the soil can sustain endless replanting. Eucalyptus plantations are also used as wind breaks. Brazil's plantations have world-record rates of growth, typically over 40 cubic metres per hectare per year,[19] and commercial harvesting occurs after years 5. Due to the continual development and governmental funding, year-on-year growth is consistently being improved. Eucalyptus can produce up to 100 cubic metres per hectare per year. Brazil has become the top exporter and producer of Eucalyptus roundwood and pulp, and has played an important role in developing the Australian market through the country's[clarification needed] committed research in this area. The local iron producers in Brazil rely heavily on sustainably grown Eucalyptus for charcoal; this has greatly pushed up the price of charcoal in recent years. The plantations are generally owned and operated for national and international industry by timber asset companies such as Thomson Forestry, Greenwood Management or cellulose producers such as Aracruz Cellulose and Stora Enso. In the 1990’s, Brazil exported approximately $1 billion, and by 2005, $3.5 billion.[clarification needed] This trade surplus has drawn large amounts of foreign investments to the agricultural sector. The European Investment Bank and the World Bank have given full public support for foreign investment in Brazil’s pulp and paper industry and cellulose processing plants. Private industry in Brazil has invested $12 billion so far in pulp and paper since 1993 and has recently pledged to invest an extra $14 billion within the sector over the next decade.[when?] The forest products industry accounts for 3% of all global trade accounting for over $200 billion USD per year. The recent presence of many foreign TIMO's (Timberland Investment Management Organizations) is a reassurance of the economic potential of the forestry activity. Worldwide TIMO's manage assets worth more than $52 million, of which $8 billion is to be invested into Brazils developments before 2012.

Overall, South America is expected to produce 55% of the world's Eucalyptus round-wood by 2010.

Africa

Ethiopia. Eucalyptus was introduced to Ethiopia in either 1894 or 1895, either by Emperor Menelik II's French advisor Mondon-Vidailhet or by the Englishman Captain O'Brian. Menelik II endorsed its planting around his new capital city of Addis Ababa because of the massive deforestation around the city for firewood. According to Richard R.K. Pankhurst, "The great advantage of the eucalypts was that they were fast growing, required little attention and when cut down grew up again from the roots; it could be harvested every ten years. The tree proved successful from the onset".[20] Plantations of eucalypts spread from the capital to other growing urban centers such as Debre Marqos. Pankhurst reports that the most common species found in Addis Ababa in the mid-1960s was E. globulus, although he also found E. melliodora and E. rostrata in significant numbers. David Buxton, writing of central Ethiopia in the mid-1940s, observed that eucalyptus trees "have become an integral -- and a pleasing -- element in the Shoan landscape and has largely displaced the slow-growing native 'cedar' Juniperus procera)."[21]

It was commonly believed that the thirst of the Eucalyptus "tended to dry up rivers and wells", creating such opposition to the species that in 1913 a proclamation was issued ordering a partial destruction of all standing trees, and their replacement with mulberry trees. Pankhurst reports, "The proclamation however remained a dead letter; there is no evidence of eucalypts being uprooted, still less of mulberry trees being planted."[22] Eucalypts remain a defining feature of Addis Ababa.

Madagascar. Much of Madagascar's original native forest has been replaced with Eucalyptus, threatening biodiversity by isolating remaining natural areas such as Andasibe-Mantadia National Park.

South Africa. Numerous Eucalyptus species have been introduced into South Africa, mainly for timber and firewood but also for ornamental purposes. They are popular with beekeepers for the honey they provide.[23] However, in South Africa they are considered invasive, with their water-sucking capabilities threatening water supplies. They also release a chemical into the surrounding soil which kills native competitors.[6]

Eucalyptus seedlings are usually unable to compete with the indigenous grasses, but after a fire when the grass cover has been removed, a seed-bed may be created. The following Eucalyptus species have been able to become naturalised in South Africa: E. camaldulensis, E. cladocalyx, E. diversicolor, E. grandis and E. lehmannii.[23]

Zimbabwe. As in South Africa, many Eucalyptus species have been introduced into Zimbabwe, mainly for timber and firewood, and E. robusta and E. tereticornis have been recorded as having become naturalised there.[23]

Europe

In continental Portugal, the Azores and Galicia numerous oak forests have been replaced with eucalyptus, which are farmed for pulpwood, with severe effects on wildlife.

In Italy, the eucalyptus only arrived at the turn of the 19th Century and large scale plantations were started at the beginning of the 20th Century with the aim of drying up swampy ground to defeat malaria. This, their rapid growth in the Italian climate and excellent function as windbreaks has made them a common sight in the Center and South of the country, including the islands of Sardinia and Sicily. They are also valued for the characteristic smelling and tasting honey that is produced from them. The variety of eucalyptus most commonly found in Italy is Eucalyptus camaldulensis.[24]

History

Although eucalypts must have been seen by the very early European explorers and collectors, no botanical collections of them are known to have been made until 1770 when Joseph Banks and Daniel Solander arrived at Botany Bay with Captain James Cook. There they collected specimens of E. gummifera and later, near the Endeavour River in northern Queensland, E. platyphylla; neither of these species was named as such at the time.

In 1777, on Cook's third expedition, David Nelson collected a eucalypt on Bruny Island in southern Tasmania. This specimen was taken to the British Museum in London, and was named Eucalyptus obliqua by the French botanist L'Héritier, who was working in London at the time. He coined the generic name from the Greek roots eu and calyptos, meaning "well" and "covered" in reference to the operculum of the flower bud which protects the developing flower parts as the flower develops and is shed by the pressure of the emerging stamens at flowering. It was most likely an accident that L'Heritier chose a feature common to all eucalypts.

The name obliqua was derived from the Latin obliquus, meaning "oblique", which is the botanical term describing a leaf base where the two sides of the leaf blade are of unequal length and do not meet the petiole at the same place.

E. obliqua was published in 1788-89, which coincided with the first official European settlement of Australia. Between then and the turn of the 19th century, several more species of Eucalyptus were named and published. Most of these were by the English botanist James Edward Smith and most were, as might be expected, trees of the Sydney region. These include the economically valuable E. pilularis, E. saligna and E. tereticornis.

The first endemic Western Australian Eucalyptus to be collected and subsequently named was the Yate (E. cornuta) by the French botanist Jacques Labillardière, who collected in what is now the Esperance area in 1792.[8]

Several great Australian botanists were active during the 19th century, particularly Ferdinand von Mueller, whose work on eucalypts contributed greatly to the first comprehensive account of the genus in George Bentham's Flora Australiensis in 1867, which today remains the only complete Australian flora. The account is the most important early systematic treatment of the genus. Bentham divided it into five series whose distinctions were based on characteristics of the stamens, particularly the anthers (Mueller, 1879-84), work elaborated by Joseph Henry Maiden (1903-33) and still further by William Faris Blakely (1934). The anther system became too complex to be workable and more recent systematic work has concentrated on the characteristics of buds, fruits, leaves and bark.

See also

Photo gallery

Eucalyptus sideroxylon, showing fruit (capsules) & buds with operculum present.

Eucalyptus forest in East Gippsland, Victoria. Mostly Eucalyptus albens (white box).

Eucalyptus forest in East Gippsland, Victoria. Mostly Eucalyptus albens (white box).

Eucalyptus forest in East Gippsland, Victoria. Mostly Eucalyptus albens (white box).

A Eucalyptus tree with the sun shining through its branches.

Eucalyptus bridgesiana (Apple box) on Red Hill, Australian Capital Territory.

Eucalyptus gunnii planted in southern England. The lower part of the trunk is covered in ivy.

Eucalyptus cinerea x pulverulenta - National Botanical Gardens Canberra

Eucalyptus gall

Eucalyptus grandis. Province of Buenos Aires, Argentina.

Eucalyptus plantation near Viveiro, in Galicia in Northwest Spain. Mostly Eucalyptus globulus

A Snow Gum (E. pauciflora), in winter in the Australian Alps

Eucalyptus rubida (Candlebark gum) in Burra, New South Wales.

This tree in Heathcote National Park has a serious problem.

Corymbia maculata trees South Coast New South Wales

Eucalyptus chapmaniana (Bogong Gum) in Kew Gardens, London

Eucalyptus regnans trees in Sherbrooke Forest, Victoria

Notes

  1. ^ "Eucalyptus L'Hér.". Germplasm Resources Information Network. United States Department of Agriculture. 2009-01-27. http://www.ars-grin.gov/cgi-bin/npgs/html/genus.pl?4477. Retrieved 2010-02-28.
  2. ^ Sunset Western Garden Book, 1995:606–607
  3. ^ Gledhill, D. (2008). The Names of Plants (4 ed.). Cambridge University Press. p. 158. ISBN 9780521866453. http://books.google.com/books?id=NJ6PyhVuecwC.
  4. ^ a b Luzar J. (2007). The Political Ecology of a “Forest Transition”: Eucalyptus forestry in the Southern Peruvian. Ethnobotany Research & Applications.
  5. ^ a b WorldWatch Institute. (2007) State of the World: Our Urban Future.
  6. ^ a b c VOA. (2005) South Africa Water Project Clears Water-Guzzling Alien Plant Infestations.
  7. ^ a b Santos, Robert L. (1997). "Section Three: Problems, Cares, Economics, and Species". The Eucalyptus of California. California State University. http://library.csustan.edu/bsantos/section3.htm.
  8. ^ a b c d Brooker & Kleinig (2001)
  9. ^ "Tasmania's Ten Tallest Giants". Tasmanian Giant Trees Consultative Committee. http://www.gianttrees.com.au/tall.htm. Retrieved 2009-01-07.
  10. ^ "Eucalytus Roulette (con't)". Robert Sward: Poet, Novelist and Workshop Leader. http://www.robertsward.com/eucmore.htm.
  11. ^ Mrs. M. Grieve. "A Modern Herbal:Eucalyptus". http://www.botanical.com/botanical/mgmh/e/eucaly14.html. Retrieved 2005-01-27.
  12. ^ Santos, Robert L (1997). "Section Two: Physical Properties and Uses". The Eucalyptus of California. California State University. http://wwwlibrary.csustan.edu/bsantos/section2.htm#FIGHTING.
  13. ^ www.cdc.gov/od/oc/media/pressrel.r050428.htm
  14. ^ India Flint, Botanical Alchemist. "The Scent of Eucalyptus." http://www.indiaflint.com/page6.htm
  15. ^ a b Reid, J.B. & Potts, B.M. (2005). Eucalypt Biology. In: Reid et al. (eds.) Vegetation of Tasmania., pp. 198-223. Australian Government.
  16. ^ Santos, Robert L. (1997). "Seeds of Good or Seeds of Evil?". The Eucalyptus of California. California State University. http://www.library.csustan.edu/bsantos/euctoc.htm.
  17. ^ Williams, Ted (January 2002). "America's Largest Weed". Audubon Magazine. http://magazine.audubon.org/incite/incite0201.html.
  18. ^ Henter, Heather (January 2005). "Tree Wars: The Secret Life of Eucalyptus". Alumni. University of California, San Diego. http://alumni.ucsd.edu/magazine/vol2no1/features/wars.htm.
  19. ^ "Brazil Eucalyptus Potential Productivity". Colorado State University. http://lamar.colostate.edu/~binkley/Brazileucalyptus.htm.
  20. ^ Pankhurst p. 246
  21. ^ David Buxton, Travels in Ethiopia, second edition (London: Benn, 1957), p. 48
  22. ^ Pankhurst p. 247
  23. ^ a b c Palgrave, K. C. 2002: Trees of Southern Africa. Struik Publishers, Cape Town.
  24. ^ http://www.europaoggi.it/content/view/791/114/

References

External links

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