Eucalyptus

Eucalyptus

Overview
Eucalyptus
is a diverse genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of flowering
Flowering plant
The flowering plants , also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Angiosperms are seed-producing plants like the gymnosperms and can be distinguished from the gymnosperms by a series of synapomorphies...

 tree
Tree
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...

s (and a few shrubs) in the myrtle family, Myrtaceae
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...

. Members of the genus dominate the tree flora of Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

. There are more than 700 species of Eucalyptus, mostly native to Australia, and a very small number are found in adjacent areas
Trans Fly savanna and grasslands
The Trans Fly savanna and grasslands are a lowland ecoregion on the south coast of the island of New Guinea in both the Indonesian and Papua New Guinean sides of the island...

 of New Guinea
New Guinea
New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...

 and Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...

 and one, Eucalyptus deglupta
Eucalyptus deglupta
Eucalyptus deglupta is a tall tree, commonly known as the Rainbow Eucalyptus, the Mindanao Gum, or the Rainbow Gum. It is the only Eucalyptus species found naturally in the Northern Hemisphere. Its natural distribution spans New Britain, New Guinea, Ceram, Sulawesi and Mindanao.The unique...

,
ranges north to the Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , 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...

. Only 15 species occur outside Australia, and only 9 do not occur in Australia.
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Encyclopedia
Eucalyptus
is a diverse genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of flowering
Flowering plant
The flowering plants , also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Angiosperms are seed-producing plants like the gymnosperms and can be distinguished from the gymnosperms by a series of synapomorphies...

 tree
Tree
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...

s (and a few shrubs) in the myrtle family, Myrtaceae
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...

. Members of the genus dominate the tree flora of Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

. There are more than 700 species of Eucalyptus, mostly native to Australia, and a very small number are found in adjacent areas
Trans Fly savanna and grasslands
The Trans Fly savanna and grasslands are a lowland ecoregion on the south coast of the island of New Guinea in both the Indonesian and Papua New Guinean sides of the island...

 of New Guinea
New Guinea
New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...

 and Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...

 and one, Eucalyptus deglupta
Eucalyptus deglupta
Eucalyptus deglupta is a tall tree, commonly known as the Rainbow Eucalyptus, the Mindanao Gum, or the Rainbow Gum. It is the only Eucalyptus species found naturally in the Northern Hemisphere. Its natural distribution spans New Britain, New Guinea, Ceram, Sulawesi and Mindanao.The unique...

,
ranges north to the Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , 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...

. Only 15 species occur outside Australia, and only 9 do not occur in Australia. Species of Eucalyptus are cultivated throughout the tropics
Tropics
The tropics is a region of the Earth surrounding the Equator. It is limited in latitude by the Tropic of Cancer in the northern hemisphere at approximately  N and the Tropic of Capricorn in the southern hemisphere at  S; these latitudes correspond to the axial tilt of the Earth...

 and subtropics
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...

 including the Americas
Americas
The Americas, or America , are lands in the Western hemisphere, also known as the New World. In English, the plural form the Americas is often used to refer to the landmasses of North America and South America with their associated islands and regions, while the singular form America is primarily...

, Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

, Africa
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...

, the Mediterranean Basin
Mediterranean Basin
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
Middle East
The Middle East is a region that encompasses Western Asia and Northern Africa. It is often used as a synonym for Near East, in opposition to Far East...

, China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

 and the Indian Subcontinent
Indian subcontinent
The Indian subcontinent, also Indian Subcontinent, Indo-Pak Subcontinent or South Asian Subcontinent is a region of the Asian continent on the Indian tectonic plate from the Hindu Kush or Hindu Koh, Himalayas and including the Kuen Lun and Karakoram ranges, forming a land mass which extends...

.

Eucalyptus is one of three similar genera
Genera
Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...

 that are commonly referred to as "eucalypt
Eucalypt
Eucalypts are woody plants belonging to three closely related genera:Eucalyptus, Corymbia and Angophora.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...

s," the others being Corymbia
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 and spotted gums. The bloodwoods had been recognised as a distinct group within the large and diverse Eucalyptus genus since 1867...

and Angophora
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...

. Many, but far from all, are known as gum trees because many species exude copious sap
Sap
Sap may refer to:* Plant sap, the fluid transported in xylem cells or phloem sieve tube elements of a plant* Sap , a village in the Dunajská Streda District of Slovakia...

 from any break in the bark
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...

 (e.g. Scribbly Gum). The generic name is derived from the Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 words ευ (eu), meaning "well," and καλυπτος (kalyptos), meaning well "covered," which refers to the operculum
Operculum (botany)
An operculum, in botany, is a term generally used to describe a structure within a plant, moss, or fungus acting as a cap, flap, or lid. In plants, it may also be called a bud cap.Examples of structures identified as opercula include:...

 on the calyx
Sepal
A sepal is a part of the flower of angiosperms . Collectively the sepals form the calyx, which is the outermost whorl of parts that form a flower. Usually green, sepals have the typical function of protecting the petals when the flower is in bud...

 that initially conceals the flower
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 effect reproduction, usually by providing a mechanism for the union of sperm with eggs...

.

Some Eucalyptus species have attracted attention from global development
Development economics
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,...

 researchers and environmentalists. Such species have desirable traits such as being fast-growing sources of wood, producing oil
Eucalyptus 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...

 that can be used for cleaning and functions as a natural insecticide
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...

, or an ability to be used to drain swamp
Swamp
A swamp is a wetland with some flooding of large areas of land by shallow bodies of water. A swamp generally has a large 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 swamp...

s and thereby reduce the risk of malaria
Malaria
Malaria is a mosquito-borne infectious disease of humans and other animals caused by eukaryotic protists of the genus Plasmodium. The disease results from the multiplication of Plasmodium parasites within red blood cells, causing symptoms that typically include fever and headache, in severe cases...

. Outside their natural ranges, eucalypts are both lauded for their beneficial economic impact on poor populations and derided for being invasive
Invasive species
"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, leading to controversy over their total impact.

Description







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
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...

 can be divided into.

As a generalisation "forest
Forest
A forest, also referred to as a wood or the woods, is an area with a high density of trees. As with cities, depending where you are in the world, what is considered a forest may vary significantly in size and have various classification according to how and what of the forest is composed...

 trees" are single-stemmed and have a crown
Crown (botany)
The crown of a plant refers to the totality of the plant's aboveground parts, including stems, leaves, and reproductive structures. A plant canopy consists of one or more plant crowns growing in a given area....

 forming a minor proportion of the whole tree height. "Woodland
Woodland
Ecologically, a woodland is a low-density forest forming open habitats with plenty of sunlight and limited shade. Woodlands may support an understory of shrubs and herbaceous plants including grasses. Woodland may form a transition to shrubland under drier conditions or during early stages of...

 trees" are single-stemmed although they may branch at a short distance above ground level.

"Mallees
Mallee (habit)
Mallee is the growth habit of certain eucalypt species that grow with multiple stems springing from an underground lignotuber, usually to a height of no more than ten metres...

" are multi-stemmed from ground level, usually less than 10 m (32.8 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
Shrub
A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...

.

Two other tree forms are notable in Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...

 and described using the native names "mallet" and "marlock". The "mallet
Mallet (habit)
A mallet is a is small-tree form of Eucalyptus found in Western Australia.Unlike the mallee, it is single-stemmed and lacks a lignotuber.Trees of this form have a slender trunk, steeply-angled branches and sometimes form thickets...

" is a small to medium-sized tree that does not produce lignotuber
Lignotuber
A lignotuber is a starchy swelling of the root crown possessed by some plants as a protection against destruction of the plant stem by fire. The crown contains buds from which new stems may sprout, and a sufficient store of nutrients to support a period of growth in the absence of...

s 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
Eucalyptus forrestiana
Eucalyptus forrestiana, commonly known as Fuchsia Gum, Forrest's Mallee or Forrest's Marlock , is a small tree which occurs in an area near Esperance in Western Australia....

, E. salubris
Eucalyptus salubris
Eucalyptus salubris, commonly known as Gimlet, Fluted Gum Tree, Gimlet Gum and Silver-topped Gimlet, is a gum tree endemic to low-rainfall areas of the wheatbelt and goldfields regions of Western Australia.-Description:...

, E. clivicola and E. ornata. The smooth bark
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...

 of mallets often has a satiny sheen and may be white, cream, grey, green or copper.

The term marlock
Marlock
A marlock or mallet is a shrubby or small-tree form of Eucalyptus found in Western Australia.Unlike the mallee, it is single-stemmed and lacks a lignotuber...

has been variously used; in Forest Trees of Australia it is defined as a small tree without lignotuber
Lignotuber
A lignotuber is a starchy swelling of the root crown possessed by some plants as a protection against destruction of the plant stem by fire. The crown contains buds from which new stems may sprout, and a sufficient store of nutrients to support a period of growth in the absence of...

s 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
Eucalyptus platypus
Eucalyptus platypus, also known as the Moort or Round-leaved Moort, is a small tree which occurs in an area between Albany and Esperance in Western Australia.-Description:...

, 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
Gold mining
Gold mining is the removal of gold from the ground. There are several techniques and processes by which gold may be extracted from the earth.-History:...

 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
Convention (norm)
A convention is a set of agreed, stipulated or generally accepted standards, norms, social norms or criteria, often taking the form of a custom....

 of:
  • Small — to 10 m (32.8 ft) in height
  • Medium-sized — 10–30 m (32.8–98.4 ft)
  • Tall — 30–60 m (98.4–196.9 ft)
  • Very tall — over 60 m (196.9 ft)

Leaves


Nearly all Eucalyptus are evergreen
Evergreen
In botany, an evergreen plant is a plant that has leaves in all seasons. This contrasts with deciduous plants, which completely lose their foliage during the winter or dry season.There are many different kinds of evergreen plants, both trees and shrubs...

 but some tropical species lose their leaves at the end of the dry season. As in other members of the myrtle
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...

 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.

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
Eucalyptus melanophloia
Eucalyptus melanophloia, commonly known as Silver-leaved Ironbark, isa species of Eucalyptus which is native to New South Wales and Queensland in Australia. It is a tall tree, growing up to 20 metres in height....

and E. setosa retain the juvenile leaf form even when the plant is reproductively mature. Some species, such as E. macrocarpa
Eucalyptus macrocarpa
Eucalyptus macocarpa, or Mottlecah, is a mallee Eucalyptus that is native to the south-west of Western Australia and noted for its large, spectacular flowers.-Description:...

, 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
Eucalyptus caesia
Eucalyptus caesia, commonly known as Caesia, Gungurru or Silver Princess, is a mallee of the Eucalyptus genus. It is endemic to the central Wheatbelt region of Western Australia, where it is found on a small number of granite outcrops. The name "silver" refers to the white powder that covers the...

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.

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
Eucalyptus oleosa
Eucalyptus oleosa, red mallee, is a native tree of Australia. The leaves were once harvested for the production of cineole based eucalyptus oil. These days Eucalyptus cneorifolia is used because of a higher oil content in new growth....

, the seedling leaves after the second leaf pair are often clustered in a detectable spiral
Spiral
In mathematics, a spiral is a curve which emanates from a central point, getting progressively farther away as it revolves around the point.-Spiral or helix:...

 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.



Flowers



The most readily recognisable characteristics of Eucalyptus species are the distinctive flowers and fruit (capsules or "gumnuts"). Flowers have numerous fluffy stamen
Stamen
The stamen is the pollen producing reproductive organ of a flower...

s which may be white, cream, yellow, pink or red; in bud, the stamens are enclosed in a cap known as an operculum
Operculum (botany)
An operculum, in botany, is a term generally used to describe a structure within a plant, moss, or fungus acting as a cap, flap, or lid. In plants, it may also be called a bud cap.Examples of structures identified as opercula include:...

 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
Eucalyptus cinerea
Eucalyptus cinerea, commonly known as the Argyle apple or Mealy Stringybark, is a small to medium sized tree with rough bark, persistent on the trunk and larger branches, thick, fibrous, longitudinally furrowed, reddish-brown to grey-brown....

and Eucalyptus perriniana
Eucalyptus perriniana
Eucalyptus perriniana, commonly known as Spinning Gum, is a tree or mallee which is native to New South Wales, Victoria and Tasmania in Australia.-References:*...

are notable exceptions.


Bark





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
Eucalyptus cladocalyx
The Sugar Gum is a eucalypt from South Australia. It is found naturally in three distinct populations - in the Flinders Ranges, Eyre Peninsula and on Kangaroo Island. Sugar Gums from the Flinders Ranges reach up to 35m in height and have the classic "gum" habit - with a straight trunk and steep...

). 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
Eucalyptus jacksonii
The Red Tingle of south west Western Australia is one of the tallest trees in the state and can measure up to 24 metres round at the base and grow to a height of 75 metres and live for up to 400 years....

, E. obliqua
Eucalyptus obliqua
Eucalyptus obliqua, commonly known as Australian Oak, Brown Top, Brown Top Stringbark, Messmate, Messmate Stringybark, Stringybark and Tasmanian Oak, is a hardwood tree native to south-eastern Australia....

and E. porosa
Eucalyptus porosa
Eucalyptus porosa, known by the common name of Mallee Box, is a species of eucalypt or gum tree, native to southern Australia.Depending on location, E. porosa can develop into a multi-trunked mallee, or it may develop into a thick, straight, single-trunked tree over 10 metres tall.E. porosa is an...

.

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
Eucalyptus clelandii
Eucalyptus clelandii, commonly known as Cleland's blackbutt, is a species of eucalypt native to Western Australia....

. In some species in this category, for example E. youngiana
Eucalyptus youngiana
Eucalyptus youngiana, commonly known as Large-fruited Mallee, Ooldea Mallee and Yarldarlba, is a tree that occurs in arid and semi-arid areas of southern Western Australia and South Australia.-Description:...

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
Eucalyptus deglupta
Eucalyptus deglupta is a tall tree, commonly known as the Rainbow Eucalyptus, the Mindanao Gum, or the Rainbow Gum. It is the only Eucalyptus species found naturally in the Northern Hemisphere. Its natural distribution spans New Britain, New Guinea, Ceram, Sulawesi and Mindanao.The unique...

.

Bark characteristics

  • Stringybark
    Stringybark
    A stringybark can be any of the many Eucalyptus species which have thick, fibrous bark. Like all eucalypts, stringybarks belong to the Myrtaceae family. In exceptionally fertile locations some stringybark species A stringybark can be any of the many Eucalyptus species which have thick, fibrous...

     — consists of long fibres and can be pulled off in long pieces. It is usually thick with a spongy texture.
  • Ironbark
    Ironbark
    Ironbark is a common name of a number of species in three taxonomic groups within the genus Eucalyptus that have dark, deeply furrowed bark....

     — is hard, rough and deeply furrowed. It is impregnated with dried kino (a sap exuded by the tree) which gives a dark red or even black colour.
  • Tessellated — bark is broken up into many distinct flakes. They are corkish
    Cork (material)
    Cork is an impermeable, buoyant material, a prime-subset of bark tissue that is harvested for commercial use primarily from Quercus suber , which is endemic to southwest Europe and northwest Africa...

     and can flake off.
  • Box — has short fibres. Some also show tessellation.
  • Ribbon — this has the bark coming off in long thin pieces but still loosely attached in some places. They can be long ribbons, firmer strips or twisted curls.

Carbon dioxide absorption of a Eucalyptus is 300 kg/yr

Species and hybridism


There are over 700 species
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...

 of Eucalyptus; refer to the List of Eucalyptus species for a comprehensive list of species. Some have diverged
Divergent evolution
Divergent evolution is the accumulation of differences between groups which can lead to the formation of new species, usually a result of diffusion of the same species to different and isolated environments which blocks the gene flow among the distinct populations allowing differentiated fixation...

 from the mainstream of the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 to the extent that they are quite isolated genetically
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....

 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
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

 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
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....

, 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.

Renantherin, a phenolic compound present in the leaves of some Eucalypstus species, allows chemotaxonomic
Chemotaxonomy
Chemotaxonomy , also called chemosystematics, is the attempt to classify and identify organisms , according to demonstrable differences and similarities in their biochemical compositions. The compounds studied in most of the cases are mostly proteins, amino acids and peptides...

 discrimanation in the sections renantheroideae and renantherae and the ratio of the amount of leucoanthocyanins varies considerably in certain species.

Related genera


A small genus of similar trees, Angophora
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...

, 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
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 Corymbia
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 and spotted gums. The bloodwoods had been recognised as a distinct group within the large and diverse Eucalyptus genus since 1867...

. 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".

Tall timber


Several eucalypts are among the tallest trees in the world. Eucalyptus regnans
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...

, the Australian Mountain Ash, is the tallest of all flowering plants (Angiosperms); today, the tallest measured specimen named Centurion
Centurion (tree)
The Centurion is the tallest Swamp Gum tree in the world, thus making Eucalyptus regnans the second highest tree species in the world after Coast Redwood and the highest angiosperm in world...

 is 99.6 m (326.8 ft) tall. Only Coast Redwood is taller and Coast Douglas-fir
Coast Douglas-fir
Pseudotsuga menziesii, known as Douglas-fir, Oregon Pine, or Douglas spruce, is an evergreen conifer species native to western North America. Its variety Pseudotsuga menziesii var. menziesii, also known as coast Douglas-fir grows in the coastal regions, from west-central British Columbia, Canada...

 about the same; they are conifers (Gymnosperm
Gymnosperm
The gymnosperms are a group of seed-bearing plants that includes conifers, cycads, Ginkgo, and Gnetales. The term "gymnosperm" comes from the Greek word gymnospermos , meaning "naked seeds", after the unenclosed condition of their seeds...

). Six other eucalypt species exceed 80 metres in height: Eucalyptus obliqua
Eucalyptus obliqua
Eucalyptus obliqua, commonly known as Australian Oak, Brown Top, Brown Top Stringbark, Messmate, Messmate Stringybark, Stringybark and Tasmanian Oak, is a hardwood tree native to south-eastern Australia....

, Eucalyptus delegatensis
Eucalyptus delegatensis
Eucalyptus delegatensis, commonly known as Alpine Ash or Gum-topped stringybark or White-top, is a sub-alpine or temperate tree of southeastern Australia. A straight, grey-trunked tree, it reaches heights of over 90 metres in suitable conditions. The tallest currently known specimen is located in...

, Eucalyptus diversicolor, Eucalyptus nitens
Eucalyptus nitens
Eucalyptus nitens, commonly known as Shining Gum, is a Eucalypt species native to Victoria and eastern New South Wales, Australia. It grows in wet forests and rainforest margins on fertile soils in cool high-rainfall areas.-Description:...

, Eucalyptus globulus
Eucalyptus globulus
The Tasmanian Blue Gum, Southern Blue Gum or Blue Gum, is an evergreen tree, one of the most widely cultivated trees native to Australia. They typically grow from 30 to 55 m tall. The tallest currently known specimen in Tasmania is 90.7 m tall...

and Eucalyptus viminalis.

Frost intolerance


Most eucalypts are not tolerant of frost, or only tolerate light frosts down to -5 °C; the hardiest are the so-called Snow Gums, such as Eucalyptus pauciflora
Eucalyptus pauciflora
The Snow Gum is a small tree or large shrub native to eastern Australia.-Habitat:It is usually found in the subalpine habitats of eastern Australia. Snow Gums also grow in lowland habitats where they can reach heights of up to 20 metres. Lowland Snow Gum is sometimes known as White Sallee, Cabbage...

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
Tasmania
Tasmania is an Australian island and state. It is south of the continent, 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 507,626 , of whom almost half reside in the greater Hobart...

 such as Eucalyptus coccifera
Eucalyptus coccifera
Eucalyptus coccifera, the Tasmanian snow gum or the Mount Wellington Peppermint, is a native tree of Tasmania.It grows as a shrub on margins of the alpine Central Highland Tasmania....

, Eucalyptus subcrenulata, and Eucalyptus gunnii, have produced extreme cold-hardy forms and it is seed procured from these genetically
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....

 hardy strains that are planted for ornament in colder parts of the world.

Animal relationships




An essential oil
Essential oil
An essential oil is a concentrated hydrophobic liquid containing volatile aroma compounds from plants. Essential oils are also known as volatile oils, ethereal oils or aetherolea, or simply as the "oil of" the plant from which they were extracted, such as oil of clove...

 extracted from Eucalyptus leaves contains compounds that are powerful natural disinfectants and can be toxic in large quantities. Several marsupial herbivores, notably koala
Koala
The koala is an arboreal herbivorous marsupial native to Australia, and the only extant representative of the family Phascolarctidae....

s and some possum
Possum
A possum is any of about 70 small to medium-sized arboreal marsupial species native to Australia, New Guinea, and Sulawesi .Possums are quadrupedal diprotodont marsupials with long tails...

s, are relatively tolerant of it. The close correlation of these oils with other more potent toxins called formylated phloroglucinol
Phloroglucinol
Phloroglucinol is a benzenetriol. It is an organic compound that is used in the synthesis of pharmaceuticals and explosives. This molecule exists in two forms, or tautomers, 1,3,5-trihydroxybenzene, which has phenol-like, and 1,3,5-cyclohexanetrione , which has ketone-like character. These two...

 compounds allows koalas and other marsupial
Marsupial
Marsupials are an infraclass of mammals, characterized by giving birth to relatively undeveloped young. Close to 70% of the 334 extant species occur in Australia, New Guinea, and nearby islands, with the remaining 100 found in the Americas, primarily in South America, but with thirteen in Central...

 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 pollinator
Pollinator
A pollinator is the biotic agent that moves pollen from the male anthers of a flower to the female stigma of a flower to accomplish fertilization or syngamy of the female gamete in the ovule of the flower by the male gamete from the pollen grain...

s including insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...

s, birds, bats and possum
Possum
A possum is any of about 70 small to medium-sized arboreal marsupial species native to Australia, New Guinea, and Sulawesi .Possums are quadrupedal diprotodont marsupials with long tails...

s. 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
Longhorn beetle
The longhorn beetles are a cosmopolitan family of beetles, typically characterized by extremely long antennae, which are often as long as or longer than the beetle's body...

 Phoracantha semipunctata and the aphid-like psyllids known as "bell lerps
Bell Miner
The Bell Miner, Manorina melanophrys, colloquially known as the Bellbird, is a colonial honeyeater endemic to southeastern Australia. They were given their common name because they feed almost exclusively on the dome-like coverings of certain psyllid bugs, referred to as "bell lerps," that feed on...

", both of which have become established as pests throughout the world wherever eucalypts are cultivated.

Adaptation to fire



Eucalypts originated between 35 and 50 million years ago, not long after Australia-New Guinea separated from Gondwana
Gondwana
In paleogeography, Gondwana , originally Gondwanaland, was the southernmost of two supercontinents that later became parts of the Pangaea supercontinent. It existed from approximately 510 to 180 million years ago . Gondwana is believed to have sutured between ca. 570 and 510 Mya,...

, 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
Casuarina
Casuarina is a genus of 17 species in the family Casuarinaceae, native to Australasia, southeast Asia, and islands of the western Pacific Ocean. It was once treated as the sole genus in the family, but has been split into three genera .They are evergreen shrubs and trees growing to 35 m tall...

and Acacia
Acacia
Acacia is a genus of shrubs and trees belonging to the subfamily Mimosoideae of the family Fabaceae, first described in Africa by the Swedish botanist Carl Linnaeus in 1773. Many non-Australian species tend to be thorny, whereas the majority of Australian acacias are not...

species.

The aridification of Australia during the mid-tertiary period (25-40 million years ago), combined with the annual penetration of tropical convection storms, and associated lightning, deep into the continental interior stimulated the gradual evolution, diversification and geographic expansion of the flammable biota. The absence of great rivers or mountain chains meant that there were no geographic barriers to check the spread of fires. From the monsoonal 'cradle', fire-promoting species expanded into higher rainfall environments, where lightning was less frequent, gradually displacing the Gondwanan rainforest from all but the most fire-sheltered habitats.

The two valuable timber trees, Alpine Ash E. delegatensis
Eucalyptus delegatensis
Eucalyptus delegatensis, commonly known as Alpine Ash or Gum-topped stringybark or White-top, is a sub-alpine or temperate tree of southeastern Australia. A straight, grey-trunked tree, it reaches heights of over 90 metres in suitable conditions. The tallest currently known specimen is located in...

and Australian Mountain Ash E. regnans
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...

, are killed by fire and only regenerate from seed. The same 2003 bushfire that had little impact on forests around Canberra
Canberra
Canberra is the capital city of Australia. With a population of over 345,000, it is Australia's largest inland city and the eighth-largest city overall. The city is located at the northern end of the Australian Capital Territory , south-west of Sydney, and north-east of Melbourne...

 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.

Fire hazard



On warm days vaporised Eucalyptus oil rises above the bush
The Bush
"The bush" is a term used for rural, undeveloped land or country areas in certain countries.-Australia:The term is iconic in Australia. In reference to the landscape, "bush" describes a wooded area, intermediate between a shrubland and a forest, generally of dry and nitrogen-poor soil, mostly...

 to create the characteristic distant blue haze of the Australian landscape. Eucalyptus oil is highly flammable (ignited trees have been known to explode) and bushfires can travel easily through the oil-rich air of the tree crowns. Eucalypts obtain their long-term fire survivability from their ability to regenerate from epicormic bud
Epicormic shoot
An epicormic shoot is a shoot growing from an epicormic bud which lies underneath the bark of a trunk, stem, or branch of a plant.-Epicormic buds:...

s situated deep within their thick bark, and lignotuber
Lignotuber
A lignotuber is a starchy swelling of the root crown possessed by some plants as a protection against destruction of the plant stem by fire. The crown contains buds from which new stems may sprout, and a sufficient store of nutrients to support a period of growth in the absence of...

s, or by producing serotinous
Serotiny
Serotiny is an ecological adaptation exhibited by some seed plants, in which seed release occurs in response to an environmental trigger, rather than spontaneously at seed maturation. The most common and best studied trigger is fire, and the term serotiny is often used to refer to this specific case...

 fruits.

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
Plant litter
Plant litter, leaf litter or tree litter is dead plant material, such as leaves, bark, needles, and twigs, that has fallen to the ground. Litter provides habitat for small animals, fungi, and plants, and the material may be used to construct nests. As litter decomposes, nutrients are released to...

 which is high in phenolics, preventing its breakdown by fungi and thus accumulates as large amounts of dry, combustible fuel. Consequently, dense eucalypt plantings may be subject to catastrophic firestorms. In fact, almost thirty years before the 1991 Oakland, California
Oakland, California
Oakland is a major West Coast port city on San Francisco Bay in the U.S. state of California. It is the eighth-largest city in the state with a 2010 population of 390,724...

 fires, a study of Eucalyptus in the area warned that the litter beneath the trees builds up very rapidly and should be regularly monitored and removed. It has been estimated that 70% of the energy released through the combustion of vegetation in the Oakland fire was due to eucalyptus. In a National Park Service
National Park Service
The National Park Service is the U.S. federal agency that manages all national parks, many national monuments, and other conservation and historical properties with various title designations...

 study, it was found that the fuel load (in tons per acre) of non-native Eucalyptus woods is almost three times as great as native oak woodland.

Falling branches



Some species of gum trees drop branches unexpectedly. In Australia, Parks Victoria
Parks Victoria
-Department:Parks Victoria was established in December 1996 as a statutory authority, reporting to the Minister for Environment and Climate Change. The Parks Victoria Act 1998 makes Parks Victoria responsible for managing national parks, reserves and other land under the control of the state,...

 warns campers not to camp under River Red Gums. Some Councils in Australia such as Gosnells in WA have removed eucalypts after reports of damage from dropped branches, even in the face of lengthy, well publicised protests to protect particular trees. A former Australian National Botanic Gardens director and consulting arborist, Robert Boden, has been quoted referring to "summer branch drop". Dropping of branches is recognised in Australia literature through the fictional death of Judy in Seven Little Australians
Seven Little Australians
Seven Little Australians is a classic Australian children's novel by Ethel Turner. Set mainly in Sydney in the 1880s, it relates the adventures of the seven mischievous Woolcot children, their stern army father Captain Woolcot and flighty stepmother Esther.In 1994 the novel was the only book by an...

. Although all large trees can drop branches, the weight of eucalyptus wood is high due to its density and high resin content.

Cultivation and uses


Eucalyptus was first introduced from Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

 to the rest of the world by Sir Joseph Banks
Joseph Banks
Sir Joseph Banks, 1st Baronet, GCB, PRS was an English naturalist, botanist and patron of the natural sciences. He took part in Captain James Cook's first great voyage . Banks is credited with the introduction to the Western world of eucalyptus, acacia, mimosa and the genus named after him,...

, botanist, on the Cook
James Cook
Captain James Cook, FRS, RN was a British explorer, navigator and cartographer who ultimately rose to the rank of captain in the Royal Navy...

 expedition in 1770. It was subsequently introduced to many parts of the world, notably California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

, Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...

, Ecuador
Ecuador
Ecuador , officially the Republic of Ecuador is a representative democratic republic in South America, bordered by Colombia on the north, Peru on the east and south, and by the Pacific Ocean to the west. It is one of only two countries in South America, along with Chile, that do not have a border...

, Colombia
Colombia
Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...

, Ethiopia
Ethiopia
Ethiopia , officially known as the Federal Democratic Republic of Ethiopia, is a country located in the Horn of Africa. It is the second-most populous nation in Africa, with over 82 million inhabitants, and the tenth-largest by area, occupying 1,100,000 km2...

, Morocco
Morocco
Morocco , officially the Kingdom of Morocco , is a country located in North Africa. It has a population of more than 32 million and an area of 710,850 km², and also primarily administers the disputed region of the Western Sahara...

, Portugal
Portugal
Portugal , officially the Portuguese Republic is a country situated in southwestern Europe on the Iberian Peninsula. Portugal is the westernmost country of Europe, and is bordered by the Atlantic Ocean to the West and South and by Spain to the North and East. The Atlantic archipelagos of the...

, South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...

, Uganda
Uganda
Uganda , officially the Republic of Uganda, is a landlocked country in East Africa. Uganda is also known as the "Pearl of Africa". It is bordered on the east by Kenya, on the north by South Sudan, on the west by the Democratic Republic of the Congo, on the southwest by Rwanda, and on the south by...

, Israel
Israel
The State of Israel is a parliamentary republic located in the Middle East, along the eastern shore of the Mediterranean Sea...

, Galicia and Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

. In Portugal
Portugal
Portugal , officially the Portuguese Republic is a country situated in southwestern Europe on the Iberian Peninsula. Portugal is the westernmost country of Europe, and is bordered by the Atlantic Ocean to the West and South and by Spain to the North and East. The Atlantic archipelagos of the...

 and also Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...

, eucalypts have been planted in pulpwood
Pulpwood
Pulpwood refers to timber with the principal use of making wood pulp for paper production.-Applications:* Trees raised specifically for pulp production account for 16% of world pulp production, old growth forests 9% and second- and third- and more generation forests account for the balance...

 plantation
Plantation
A plantation is a long artificially established forest, farm or estate, where crops are grown for sale, often in distant markets rather than for local on-site consumption...

s. Eucalyptus are the basis for several industries, such as sawmilling, pulp, charcoal and others. Several species have become invasive
Invasive species
"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....

 and are causing major problems for local ecosystems, mainly due to the absence of wildlife corridors and rotations management.
Eucalypts have many uses which have made them economically
Economics
Economics is the social science that analyzes the production, distribution, and consumption of goods and services. The term economics comes from the Ancient Greek from + , hence "rules of the house"...

 important trees, and have become a cash crop
Cash crop
In agriculture, a cash crop is a crop which is grown for profit.The term is used to differentiate from subsistence crops, which are those fed to the producer's own livestock or grown as food for the producer's family...

 in poor areas such as Timbuktu
Timbuktu
Timbuktu , formerly also spelled Timbuctoo, is a town in the West African nation of Mali situated north of the River Niger on the southern edge of the Sahara Desert. The town is the capital of the Timbuktu Region, one of the eight administrative regions of Mali...

, Africa and the Peru
Peru
Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....

vian Andes
Andes
The Andes is the world's longest continental mountain range. It is a continual range of highlands along the western coast of South America. This range is about long, about to wide , and of an average height of about .Along its length, the Andes is split into several ranges, which are separated...

, despite concerns that the trees are invasive
Invasive species
"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....

 in some countries like South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...

. Best-known are perhaps the varieties Karri and Yellow box
Eucalyptus melliodora
Eucalyptus melliodora, commonly known as Yellow Box, is a medium sized to occasionally tall eucalypt. The bark is variable ranging from smooth with an irregular, short stocking, to covering most of the trunk, fibrous, dense or loosely held, grey, yellow or red-brown, occasionally very coarse,...

. 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
Ornamental plant
Ornamental plants are plants that are grown for decorative purposes in gardens and landscape design projects, as house plants, for cut flowers and specimen display...

, timber, firewood and pulpwood
Pulpwood
Pulpwood refers to timber with the principal use of making wood pulp for paper production.-Applications:* Trees raised specifically for pulp production account for 16% of world pulp production, old growth forests 9% and second- and third- and more generation forests account for the balance...

. It is also used in a number of industries, from fence posts and charcoal to cellulose
Cellulose
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand β linked D-glucose units....

 extraction for biofuel
Biofuel
Biofuel is a type of fuel whose energy is derived from biological carbon fixation. Biofuels include fuels derived from biomass conversion, as well as solid biomass, liquid fuels and various biogases...

s. Fast growth also makes eucalypts suitable as windbreak
Windbreak
A windbreak or shelterbelt is a plantation usually made up of one or more rows of trees or shrubs planted in such a manner as to provide shelter from the wind and to protect soil from erosion. They are commonly planted around the edges of fields on farms. If designed properly, windbreaks around a...

s and to reduce erosion
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...

.

Eucalypts draw a tremendous amount of water from the soil through the process of transpiration
Transpiration
Transpiration is a process similar to evaporation. It is a part of the water cycle, and it is the loss of water vapor from parts of plants , especially in leaves but also in stems, flowers and roots. Leaf surfaces are dotted with openings which are collectively called stomata, and in most plants...

. They have been planted (or re-planted) in some places to lower the water table
Water table
The water table is the level at which the submarine pressure is far from atmospheric pressure. It may be conveniently visualized as the 'surface' of the subsurface materials that are saturated with groundwater in a given vicinity. However, saturated conditions may extend above the water table as...

 and reduce soil salination
Soil salination
Soil salinity is the salt content in the soil.- Causes of soil salinity :Salt-affected soils are caused by excess accumulation of salts, typically most pronounced at the soil surface. Salts can be transported to the soil surface by capillary transport from a salt laden water table and then...

. Eucalypts have also been used as a way of reducing malaria
Malaria
Malaria is a mosquito-borne infectious disease of humans and other animals caused by eukaryotic protists of the genus Plasmodium. The disease results from the multiplication of Plasmodium parasites within red blood cells, causing symptoms that typically include fever and headache, in severe cases...

 by draining the soil in Algeria, Lebanon, Sicily, elsewhere in Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

, and California. Drainage removes swamp
Swamp
A swamp is a wetland with some flooding of large areas of land by shallow bodies of water. A swamp generally has a large 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 swamp...

s which provide a habitat for mosquito
Mosquito
Mosquitoes are members of a family of nematocerid flies: the Culicidae . The word Mosquito is from the Spanish and Portuguese for little fly...

 larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...

e, 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
Phreatic zone
The phreatic zone, or zone of saturation, is the area in an aquifer, below the water table, in which relatively all pores and fractures are saturated with water. The phreatic zone may fluctuate with changes of season and during wet and dry periods....

; thus rain or irrigation can wet the soil again.

Pulpwood


Eucalyptus is the most common short fibre source for pulpwood
Pulpwood
Pulpwood refers to timber with the principal use of making wood pulp for paper production.-Applications:* Trees raised specifically for pulp production account for 16% of world pulp production, old growth forests 9% and second- and third- and more generation forests account for the balance...

 to make pulp
Pulp (paper)
Pulp is a lignocellulosic fibrous material prepared by chemically or mechanically separating cellulose fibres from wood, fibre crops or waste paper. Wood pulp is the most common raw material in papermaking.-History:...

. Eucalyptus globulus
Eucalyptus globulus
The Tasmanian Blue Gum, Southern Blue Gum or Blue Gum, is an evergreen tree, one of the most widely cultivated trees native to Australia. They typically grow from 30 to 55 m tall. The tallest currently known specimen in Tasmania is 90.7 m tall...

and Eucalyptus grandis
Eucalyptus grandis
Eucalyptus grandis, commonly known as the Flooded gum or Rose gum, is a tall tree with smooth bark, rough at the base fibrous or flaky, grey to grey-brown...

are the most used varieties in papermaking
Papermaking
Papermaking is the process of making paper, a substance which is used universally today for writing and packaging.In papermaking a dilute suspension of fibres in water is drained through a screen, so that a mat of randomly interwoven fibres is laid down. Water is removed from this mat of fibres by...

. The fibre length of Eucalyptus is relatively short and uniform with low coarseness compared with other hardwoods commonly used as pulpwood. The fibres are slender, yet relatively thick walled. This gives uniform paper formation and high opacity
Opacity (optics)
Opacity is the measure of impenetrability to electromagnetic or other kinds of radiation, especially visible light. In radiative transfer, it describes the absorption and scattering of radiation in a medium, such as a plasma, dielectric, shielding material, glass, etc...

 that are important for all types of fine paper
Fine paper
Fine papers are printing and writing paper grades based mainly on chemical pulps. Normally the content of mechanical pulps are below 10% and the amount of fillers in the range 5–25%.-Production:...

s. The low coarseness is important for high quality coated paper
Coated paper
Coated paper is paper which has been coated by a compound to impart certain qualities to the paper, including weight, surface gloss, smoothness or reduced ink absorbency. Kaolinite or calcium carbonate are used to coat paper for high quality printing used in packaging industry and in magazines...

s. Eucalyptus is suitable for many tissue paper
Tissue paper
Tissue paper is a lightweight paper or, light crêpe paper. Tissue can be made both from virgin and recycled paper pulp.-Properties:Key properties are: strength, absorbency, basis weight, thickness , brightness, stretch, appearance and comfort....

s as the short and slender fibres gives a high number of fibres per gram and low coarseness contributes to softness.

Eucalyptus oil


Eucalyptus oil
Eucalyptus 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...

 is readily steam distilled
Steam distillation
Steam distillation is a special type of distillation for temperature sensitive materials like natural aromatic compounds....

 from the leaves and can be used for cleaning, deodorising, and in very small quantities in food
Food
Food is any substance consumed to provide nutritional support for the body. It is usually of plant or animal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals...

 supplements, especially sweets
SweetS
was a Japanese idol group. Put together through auditions, the group debuted in 2003 on the avex trax label. Although the group met minor success, they disbanded after three years with the release of a final single in June 2006....

, cough drops, toothpaste
Toothpaste
Toothpaste is a paste or gel dentifrice used with a toothbrush as an accessory to clean and maintain the aesthetics and health of teeth. Toothpaste is used to promote oral hygiene: it serves as an abrasive that aids in removing the dental plaque and food from the teeth, assists in suppressing...

 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).

Honey


The nectar
Nectar (plant)
Nectar is a sugar-rich liquid produced by plants. It is produced in glands called nectaries, either within the flowers, in which it attracts pollinating animals, or by extrafloral nectaries, which provide a nutrient source to animal mutualists, which in turn provide anti-herbivore protection...

 of some eucalypts produces high-quality monofloral honey
Monofloral honey
Monofloral honey is a type of honey which has a high value in the marketplace because it has a distinctive flavor or other attribute due to its being predominantly from the nectar of one plant species....

.

Music instrument


Eucalypt wood is also commonly used to make digeridoos, a traditional Australian Aboriginal wind instrument
Wind instrument
A wind instrument is a musical instrument that contains some type of resonator , in which a column of air is set into vibration by the player blowing into a mouthpiece set at the end of the resonator. The pitch of the vibration is determined by the length of the tube and by manual modifications of...

. The trunk of the tree is hollowed out by termites, and then cut down if the bore is of the correct size and shape.

Dye


All parts of Eucalyptus may be used to make dye
Dye
A dye is a colored substance that has an affinity to the substrate to which it is being applied. The dye is generally applied in an aqueous solution, and requires a mordant to improve the fastness of the dye on the fiber....

s that are substantive on protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 fibres (such as silk
Silk
Silk is a natural protein fiber, some forms of which can be woven into textiles. The best-known type of silk is obtained from the cocoons of the larvae of the mulberry silkworm Bombyx mori reared in captivity...

 and wool
Wool
Wool is the textile fiber obtained from sheep and certain other animals, including cashmere from goats, mohair from goats, qiviut from muskoxen, vicuña, alpaca, camel from animals in the camel family, and angora from rabbits....

), simply by processing the plant part with water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

. Colours to be achieved range from yellow and orange through green, tan, chocolate and deep rust red. The material remaining after processing can be safely used as mulch
Mulch
In agriculture and gardening, is a protective cover placed over the soil to retain moisture, reduce erosion, provide nutrients, and suppress weed growth and seed germination. Mulching in gardens and landscaping mimics the leaf cover that is found on forest floors....

 or fertiliser.

Eucalyptus as an invasive species


Due to similar favourable climatic conditions, Eucalyptus plantations have often replaced oak
Oak
An oak is a tree or shrub in the genus Quercus , of which about 600 species exist. "Oak" may also appear in the names of species in related genera, notably Lithocarpus...

 woodlands, for example in California, Spain and Portugal. The resulting monocultures have raised concerns about loss of biological diversity, through loss of acorn
Acorn
The acorn, or oak nut, is the nut of the oaks and their close relatives . It usually contains a single seed , enclosed in a tough, leathery shell, and borne in a cup-shaped cupule. Acorns vary from 1–6 cm long and 0.8–4 cm broad...

s that mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...

s 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. A study of the relationship between birds and eucalyptus in the San Francisco Bay Area found that bird diversity was similar in native forest vs. eucalyptus forest but the species were different. One way in which the avifauna changes is that cavity nesting birds including woodpeckers, owls, chickadees, wood ducks, etc. are depauperate in eucalyptus groves because the decay-resistant wood of these trees prevents cavity formation by decay or excavation. Also those bird species that glean insects from foliage, such as warblers and vireos, have population declines when eucalyptus replace oak forest. Birds that do well in eucalyptus groves in California like tall vertical habitat like herons and egrets (possibly because redwood trees are less available), or have longer bills, which may play a role in preventing their nostrils from being clogged by eucalyptus resin/pitch. The Point Reyes Bird Observatory observes that sometimes short-billed birds like the Ruby-crowned Kinglet are found dead beneath eucalyptus trees with their nostrils clogged with pitch.

Monarch butterflies use eucalyptus in California for over-wintering, but in some locations have a preference for Monterey pine
Monterey Pine
The Monterey Pine, Pinus radiata, family Pinaceae, also known as the Insignis Pine or Radiata Pine is a species of pine native to the Central Coast of California....

s.

North America


California. In the 1850s, Eucalyptus trees were introduced to California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

 by Australians during the California Gold Rush
California Gold Rush
The California Gold Rush began on January 24, 1848, when gold was found by James W. Marshall at Sutter's Mill in Coloma, California. The first to hear confirmed information of the gold rush were the people in Oregon, the Sandwich Islands , and Latin America, who were the first to start flocking to...

. 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 tie
Railroad tie
A railroad tie/railway tie , or railway sleeper is a rectangular item used to support the rails in railroad tracks...

s. 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."


One way in which the eucalyptus, mainly the blue gum E. globulus
Eucalyptus globulus
The Tasmanian Blue Gum, Southern Blue Gum or Blue Gum, is an evergreen tree, one of the most widely cultivated trees native to Australia. They typically grow from 30 to 55 m tall. The tallest currently known specimen in Tasmania is 90.7 m tall...

, 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 fuelled by large numbers of eucalypts close to the houses.

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.

Eucalyptus trees do exceptionally well in the Pacific Northwest: Washington, Oregon
Oregon
Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...

 and parts of British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...

.

South America


Uruguay. Antonio Lussich
Antonio Lussich
Antonio Dionisio Lussich was an Uruguayan sailor, arboricultorist and writer.-Family background:...

 introduced Eucalyptus into Uruguay
Uruguay
Uruguay ,officially the Oriental Republic of Uruguay,sometimes the Eastern Republic of Uruguay; ) is a country in the southeastern part of South America. It is home to some 3.5 million people, of whom 1.8 million live in the capital Montevideo and its metropolitan area...

 in approximately 1896, throughout what is now Maldonado Department
Maldonado Department
The Maldonado Department , with an area of and 140,192 inhabitants, is located to the southeast of Uruguay. Its capital is Maldonado.-Geography and climate:...

, 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
Acacia
Acacia is a genus of shrubs and trees belonging to the subfamily Mimosoideae of the family Fabaceae, first described in Africa by the Swedish botanist Carl Linnaeus in 1773. Many non-Australian species tend to be thorny, whereas the majority of Australian acacias are not...

 and Pine
Pine
Pines are trees in the genus Pinus ,in the family Pinaceae. They make up the monotypic subfamily Pinoideae. There are about 115 species of pine, although different authorities accept between 105 and 125 species.-Etymology:...

s, but they have not expanded so massively.)

Brazil. Eucalyptus was introduced to Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...

 in 1910, for timber
Timber
Timber may refer to:* Timber, a term common in the United Kingdom and Australia for wood materials * Timber, Oregon, an unincorporated community in the U.S...

 substitution and the charcoal
Charcoal
Charcoal is the dark grey residue consisting of carbon, and any remaining ash, obtained by removing water and other volatile constituents from animal and vegetation substances. Charcoal is usually produced by slow pyrolysis, the heating of wood or other substances in the absence of oxygen...

 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
Windbreak
A windbreak or shelterbelt is a plantation usually made up of one or more rows of trees or shrubs planted in such a manner as to provide shelter from the wind and to protect soil from erosion. They are commonly planted around the edges of fields on farms. If designed properly, windbreaks around a...

. Brazil's plantations have world-record rates of growth, typically over 40 cubic metres per hectare per year, 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 committed research in this area. The local iron producers in Brazil rely heavily on sustainably grown Eucalyptus for charcoal
Charcoal
Charcoal is the dark grey residue consisting of carbon, and any remaining ash, obtained by removing water and other volatile constituents from animal and vegetation substances. Charcoal is usually produced by slow pyrolysis, the heating of wood or other substances in the absence of oxygen...

; 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
Stora Enso
Stora Enso Oyj is a Finnish pulp and paper manufacturer, formed by the merger of Swedish mining and forestry products company Stora and Finnish forestry products company Enso-Gutzeit Oy in 1998. It is headquartered in Helsinki, and it has approximately 29,000 employees...

.

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

Africa


Ethiopia. Eucalyptus was introduced to Ethiopia
Ethiopia
Ethiopia , officially known as the Federal Democratic Republic of Ethiopia, is a country located in the Horn of Africa. It is the second-most populous nation in Africa, with over 82 million inhabitants, and the tenth-largest by area, occupying 1,100,000 km2...

 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
Addis Ababa
Addis Ababa is the capital city of Ethiopia...

 because of the massive deforestation
Deforestation
Deforestation is the removal of a forest or stand of trees where the land is thereafter converted to a nonforest use. Examples of deforestation include conversion of forestland to farms, ranches, or urban use....

 around the city for firewood
Firewood
Firewood is any wood-like material that is gathered and used for fuel. Generally, firewood is not highly processed and is in some sort of recognizable log or branch form....

. 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". Plantations of eucalypts spread from the capital to other growing urban centres such as Debre Marqos
Debre Marqos
Debre Marqos is a city and woreda in east-central Ethiopia. Located in the Misraq Gojjam Zone of the Amhara Region, it has a latitude and longitude of , and an elevation of 2,446 meters. The city is named Debre Marqos after its principal church, which was constructed in 1869 and dedicated to St....

. Pankhurst reports that the most common species found in Addis Ababa in the mid-1960s was E. globulus
Eucalyptus globulus
The Tasmanian Blue Gum, Southern Blue Gum or Blue Gum, is an evergreen tree, one of the most widely cultivated trees native to Australia. They typically grow from 30 to 55 m tall. The tallest currently known specimen in Tasmania is 90.7 m tall...

, although he also found E. melliodora
Eucalyptus melliodora
Eucalyptus melliodora, commonly known as Yellow Box, is a medium sized to occasionally tall eucalypt. The bark is variable ranging from smooth with an irregular, short stocking, to covering most of the trunk, fibrous, dense or loosely held, grey, yellow or red-brown, occasionally very coarse,...

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
Shewa
Shewa is a historical region of Ethiopia, formerly an autonomous kingdom within the Ethiopian Empire...

 landscape and has largely displaced the slow-growing native 'cedar' Juniperus procera
Juniperus procera
Juniperus procera, commonly known in English as African Juniper or East African Juniper, is a coniferous tree native to the mountains of eastern Africa from eastern Sudan south to Zimbabwe, and the southwest of the Arabian Peninsula...

)."

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." 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
Andasibe-Mantadia National Park
Andasibe-Mantadia National Park is a 155 square kilometre protected area consisting principally of primary growth forest in Alaotra-Mangoro Region in eastern Madagascar. The park's elevation ranges from 900-1250 meters, with a humid climate. Average annual precipitation is 1700 mm, with rainfall...

.

South Africa. Numerous Eucalyptus species have been introduced into South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...

, mainly for timber
Timber
Timber may refer to:* Timber, a term common in the United Kingdom and Australia for wood materials * Timber, Oregon, an unincorporated community in the U.S...

 and firewood
Firewood
Firewood is any wood-like material that is gathered and used for fuel. Generally, firewood is not highly processed and is in some sort of recognizable log or branch form....

 but also for ornamental purposes. They are popular with beekeeper
Beekeeper
A beekeeper is a person who keeps honey bees for the purposes of securing commodities such as honey, beeswax, pollen, royal jelly; pollinating fruits and vegetables; raising queens and bees for sale to other farmers; and/or for purposes satisfying natural scientific curiosity...

s for the honey
Honey
Honey is a sweet food made by bees using nectar from flowers. The variety produced by honey bees is the one most commonly referred to and is the type of honey collected by beekeepers and consumed by humans...

 they provide. 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.

Eucalyptus seedling
Seedling
thumb|Monocot and dicot seedlingsA seedling is a young plant sporophyte developing out of a plant embryo from a seed. Seedling development starts with germination of the seed. A typical young seedling consists of three main parts: the radicle , the hypocotyl , and the cotyledons...

s are usually unable to compete with the indigenous grass
Grass
Grasses, or more technically graminoids, are monocotyledonous, usually herbaceous plants with narrow leaves growing from the base. They include the "true grasses", of the Poaceae family, as well as the sedges and the rushes . The true grasses include cereals, bamboo and the grasses of lawns ...

es, 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
Eucalyptus cladocalyx
The Sugar Gum is a eucalypt from South Australia. It is found naturally in three distinct populations - in the Flinders Ranges, Eyre Peninsula and on Kangaroo Island. Sugar Gums from the Flinders Ranges reach up to 35m in height and have the classic "gum" habit - with a straight trunk and steep...

, E. diversicolor, E. grandis
Eucalyptus grandis
Eucalyptus grandis, commonly known as the Flooded gum or Rose gum, is a tall tree with smooth bark, rough at the base fibrous or flaky, grey to grey-brown...

and E. lehmannii.

Zimbabwe. As in South Africa, many Eucalyptus species have been introduced into Zimbabwe
Zimbabwe
Zimbabwe is a landlocked country located in the southern part of the African continent, between the Zambezi and Limpopo rivers. It is bordered by South Africa to the south, Botswana to the southwest, Zambia and a tip of Namibia to the northwest and Mozambique to the east. Zimbabwe has three...

, mainly for timber and firewood, and E. robusta
Eucalyptus robusta
Eucalyptus robusta, commonly known as Swamp Mahogany, Swamp Messmate or Swamp Stringybark, is a tree native to eastern Australia.-Description:...

and E. tereticornis
Eucalyptus tereticornis
Eucalyptus tereticornis is a species of tree native to eastern Australia.It has a great many common names, of which Forest Red Gum is perhaps the most widely known...

have been recorded as having become naturalised there.

Europe


In continental Portugal
Portugal
Portugal , officially the Portuguese Republic is a country situated in southwestern Europe on the Iberian Peninsula. Portugal is the westernmost country of Europe, and is bordered by the Atlantic Ocean to the West and South and by Spain to the North and East. The Atlantic archipelagos of the...

, the Azores
Azores
The Archipelago of the Azores is composed of nine volcanic islands situated in the middle of the North Atlantic Ocean, and is located about west from Lisbon and about east from the east coast of North America. The islands, and their economic exclusion zone, form the Autonomous Region of the...

 and the North of Spain (especially in the provinces of Cantabria, Vizcaya, Asturias, and Galicia) numerous oak forests have been replaced with eucalyptus, which are farmed for pulpwood, with severe effects on wildlife and the regional environments. Most of the wildfires that have raged the Iberian Peninsula in recent years have taken place in plantations of eucalyptus rather than in the more humid indigenous woods that are left.

In Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

, 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 centre and south of the country, including the islands of Sardinia
Sardinia
Sardinia is the second-largest island in the Mediterranean Sea . It is an autonomous region of Italy, and the nearest land masses are the French island of Corsica, the Italian Peninsula, Sicily, Tunisia and the Spanish Balearic Islands.The name Sardinia is from the pre-Roman noun *sard[],...

 and Sicily
Sicily
Sicily is a region of Italy, and is the largest island in the Mediterranean Sea. Along with the surrounding minor islands, it constitutes an autonomous region of Italy, the Regione Autonoma Siciliana Sicily has a rich and unique culture, especially with regard to the arts, music, literature,...

. They are also valued for the characteristic smelling and tasting honey
Honey
Honey is a sweet food made by bees using nectar from flowers. The variety produced by honey bees is the one most commonly referred to and is the type of honey collected by beekeepers and consumed by humans...

 that is produced from them. The variety of eucalyptus most commonly found in Italy is E. camaldulensis.

Asia


Eucalyptus trees have been plants in Israel
Israel
The State of Israel is a parliamentary republic located in the Middle East, along the eastern shore of the Mediterranean Sea...

 by Jewish settlers in the beginning of the 20th century in order to dry out marshy lands that caused diseases. These Eucalyptus trees still exist today in many parts of Israel. The Nilgiri Hills in Southern India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

 have Eucalyptus trees growing in great abundance. The essential oil is produced in this characteristic tea
Tea
Tea is an aromatic beverage prepared by adding cured leaves of the Camellia sinensis plant to hot water. The term also refers to the plant itself. After water, tea is the most widely consumed beverage in the world...

-growing high-altitude range of mountains found in Tamil Nadu
Tamil Nadu
Tamil Nadu is one of the 28 states of India. Its capital and largest city is Chennai. Tamil Nadu lies in the southernmost part of the Indian Peninsula and is bordered by the union territory of Pondicherry, and the states of Kerala, Karnataka, and Andhra Pradesh...

 state.

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
Joseph Banks
Sir Joseph Banks, 1st Baronet, GCB, PRS was an English naturalist, botanist and patron of the natural sciences. He took part in Captain James Cook's first great voyage . Banks is credited with the introduction to the Western world of eucalyptus, acacia, mimosa and the genus named after him,...

 and Daniel Solander
Daniel Solander
Daniel Carlsson Solander or Daniel Charles Solander was a Swedish naturalist and an apostle of Carl Linnaeus. Solander was the first university educated scientist to set foot on Australian soil.-Biography:...

 arrived at Botany Bay
Botany Bay
Botany Bay is a bay in Sydney, New South Wales, a few kilometres south of the Sydney central business district. The Cooks River and the Georges River are the two major tributaries that flow into the bay...

 with Captain James Cook. There they collected specimens of E. gummifera and later, near the Endeavour River
Endeavour River
The Endeavour River on Cape York Peninsula in Far North Queensland, Australia, was named in 1770 by Lt. James Cook, R.N., after he was forced to beach his ship, HM Bark Endeavour, for repairs in the river mouth, after damaging it on Endeavour Reef...

 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
Tasmania
Tasmania is an Australian island and state. It is south of the continent, 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 507,626 , of whom almost half reside in the greater Hobart...

. This specimen was taken to the British Museum
British Museum
The British Museum is a museum of human history and culture in London. Its collections, which number more than seven million objects, are amongst the largest and most comprehensive in the world and originate from all continents, illustrating and documenting the story of human culture from its...

 in London
London
London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...

, and was named Eucalyptus obliqua by the French botanist L'Héritier
Charles Louis L'Héritier de Brutelle
Charles Louis L'Héritier de Brutelle was an 18th century French botanist and magistrate. Born into an affluent upper-class Parisian family, connections with the French Royal Court secured him the position of Superindent of Parisian Waters and Forests at the age of twenty-six...

, 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
Operculum (botany)
An operculum, in botany, is a term generally used to describe a structure within a plant, moss, or fungus acting as a cap, flap, or lid. In plants, it may also be called a bud cap.Examples of structures identified as opercula include:...

 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
Botany
Botany, plant science, or plant biology is a branch of biology that involves the scientific study of plant life. Traditionally, botany also included the study of fungi, algae and viruses...

 term describing a leaf
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....

 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
James Edward Smith
Sir James Edward Smith was an English botanist and founder of the Linnean Society.Smith was born in Norwich in 1759, the son of a wealthy wool merchant. He displayed a precocious interest in the natural world...

 and most were, as might be expected, trees of the Sydney
Sydney
Sydney is the most populous city in Australia and the state capital of New South Wales. Sydney is located on Australia's south-east coast of the Tasman Sea. As of June 2010, the greater metropolitan area had an approximate population of 4.6 million people...

 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
Eucalyptus cornuta
Eucalyptus cornuta, commonly known as Yate, is a tree which occurs in an area between Busselton and Albany in Western Australia....

) by the French botanist Jacques Labillardière
Jacques Labillardière
Jacques-Julien Houtou de Labillardière was a French naturalist noted for his descriptions of the flora of Australia. Labillardière was a member of a voyage in search of the La Pérouse expedition...

, who collected in what is now the Esperance
Esperance, Western Australia
Esperance is a large town in the Goldfields-Esperance region of Western Australia, located on the Southern Ocean coastline approximately east-southeast of the state capital, Perth. The shire of Esperance is home to 9,536 people as of the 2006 census, its major industries are tourism, agriculture,...

 area in 1792.

Several great Australian botanists were active during the 19th century, particularly Ferdinand von Mueller
Ferdinand von Mueller
Baron Sir Ferdinand Jacob Heinrich von Mueller, KCMG was a German-Australian physician, geographer, and most notably, a botanist.-Early life:...

, whose work on eucalypts contributed greatly to the first comprehensive account of the genus in George Bentham
George Bentham
George Bentham CMG FRS was an English botanist, characterized by Duane Isely as "the premier systematic botanist of the nineteenth century".- Formative years :...

'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.

In the 20th century, scientists around the world experimented with Eucalyptus species. They hoped to grow them in the tropics, but most experimental results failed until breakthroughs in in the 1960s-1980s in species selection, silviculture, and breeding programs "unlocked" the potential of Eucalypts in the tropics. Prior to then, as Brett Bennett noted in a 2010 article, eucalypts were something of the "El Dorado" of forestry. Today, Eucalyptus is the most widely planted species in plantations around the world.

See also

  • Currency Creek Arboretum
    Currency Creek Arboretum
    thumb|right|270px|[[Dean Nicolle]] and [[Eucalyptus deanei]]thumb|right|270px|Eucalyptus conferruminataThe Currency Creek Arboretum is located in South Australia near the geographical feature and small town of Currency Creek, up from the mouth of the Murray River at Goolwa, and south of Adelaide...

  • Eucalyptol
    Eucalyptol
    Eucalyptol is a natural organic compound which is a colorless liquid. It is a cyclic ether and a monoterpenoid.Eucalyptol is also known by a variety of synonyms: 1,8-cineol, 1,8-cineole, limonene oxide, cajeputol, 1,8-epoxy-p-menthane, 1,8-oxido-p-menthane, eucalyptol, eucalyptole,...

  • Eucalyptus oil
    Eucalyptus 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...

  • List of Eucalyptus species

External links



Medicinal resources, eucalyptus essential oil

  • http://www.botanical.com/botanical/mgmh/e/eucaly14.html
  • http://www.henriettesherbal.com/eclectic/bpc1911/eucalyptus_oleu.html