''Eucalyptus'' () is a genus of over seven hundred species of flowering trees, shrubs or mallees in the myrtle family, Myrtaceae. Along with several other genera in the tribe Eucalypteae, including ''

Corymbia ''Corymbia'', commonly known as bloodwoods, is a genus of about one hundred species of tree that, along with ''Eucalyptus'', '' Angophora'' and several smaller groups, are referred to as eucalypts. Until 1990, corymbias were included in the gen ...

'', they are commonly known as eucalypts. Plants in the genus ''Eucalyptus'' have bark that is either smooth, fibrous, hard or stringy, leaves with oil glands, and sepals and

petal Petals are modified Leaf, leaves that surround the reproductive parts of flowers. They are often advertising coloration, brightly colored or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''c ...

s that are fused to form a "cap" or operculum over the

stamen The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filame ...

s. The fruit is a woody capsule commonly referred to as a "gumnut". Most species of ''Eucalyptus'' are

native Native may refer to: People * Jus soli, citizenship by right of birth * Indigenous peoples, peoples with a set of specific rights based on their historical ties to a particular territory ** Native Americans (disambiguation) In arts and entert ...

to Australia, and every state and territory has representative species. About three-quarters of Australian forests are eucalypt forests. Wildfire is a feature of the Australian landscape and many eucalypt species are adapted to fire, and resprout after fire or have seeds which survive fire. A few species are native to islands north of Australia and a smaller number are only found outside the continent. Eucalypts have been grown in plantations in many other countries because they are fast growing and have valuable timber, or can be used for

pulpwood Pulpwood is timber with the principal use of making wood pulp for paper production. Applications * Trees raised specifically for pulp production account for 15% of world pulp production, old growth forests 9% and second- and third- and more gener ...

, for

honey Honey is a sweet and viscous substance made by several bees, the best-known of which are honey bees. Honey is made and stored to nourish bee colonies. Bees produce honey by gathering and then refining the sugary secretions of plants (primar ...

production or

essential oil An essential oil is a concentrated hydrophobic liquid containing volatile (easily evaporated at normal temperatures) chemical compounds from plants. Essential oils are also known as volatile oils, ethereal oils, aetheroleum, or simply as the o ...

s. In some countries, however, they have been removed because of the danger of

forest fire A wildfire, forest fire, bushfire, wildland fire or rural fire is an unplanned, uncontrolled and unpredictable fire in an area of Combustibility and flammability, combustible vegetation. Depending on the type of vegetation present, a wildfire ...

s due to their high inflammability.

Description

Size and habit

Eucalypts vary in size and habit from shrubs to tall trees. Trees usually have a single main stem or

trunk Trunk may refer to: Biology * Trunk (anatomy), synonym for torso * Trunk (botany), a tree's central superstructure * Trunk of corpus callosum, in neuroanatomy * Elephant trunk, the proboscis of an elephant Computing * Trunk (software), in rev ...

but many eucalypts are mallees that are multistemmed from ground level and rarely taller than . There is no clear distinction between a mallee and a shrub but in eucalypts, a shrub is a mature plant less than tall and growing in an extreme environment. '' E. vernicosa'' in the Tasmanian highlands, '' E. yalatensis'' on the Nullarbor and '' E. surgens'' growing on coastal cliffs in Western Australia are examples of eucalypt shrubs. The terms "

mallet A mallet is a tool used for imparting force on another object, often made of rubber or sometimes wood, that is smaller than a maul or beetle, and usually has a relatively large head. The term is descriptive of the overall size and proport ...

" and "

marlock A marlock or moort is a shrubby or small-tree form of ''Eucalyptus'' found in Western Australia. Unlike the mallee, it is single-stemmed and lacks a lignotuber. It has a dense canopy of leaves which often extends to near ground level. Marlock spec ...

" are only applied to Western Australian eucalypts. A mallet is a tree with a single thin trunk with a steeply branching habit but lacks both a lignotuber and

epicormic buds 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 lie dormant beneath the bark, their growth suppressed by hormones from active shoots higher up ...

. '' E. astringens'' is an example of a mallet. A marlock is a shrub or small tree with a single, short trunk, that lacks a lignotuber and has spreading, densely leafy branches that often reach almost to the ground. '' E. platypus'' is an example of a marlock. ''Eucalyptus'' trees, including mallets and marlocks, are single-stemmed and include '' Eucalyptus regnans'', the tallest known flowering plant on Earth. Tree sizes follow the convention of: * Small: to in height * Medium-sized: * Tall: * Very tall: over Tasmania logging 08 Mighty tree.jpg, '' Eucalyptus regnans'', a forest tree, showing crown dimension, Tasmania TocumwalTownBeach.jpg, '' E. camaldulensis'', immature woodland trees, showing collective crown habit, Murray River, Tocumwal, New South Wales Eucalyptus cretata.jpg, '' E. cretata'', juvenile, showing low branching 'mallee' form, Melbourne, Victoria Eucalyptus angustissima1.jpg, '' E. angustissima'', showing shrub form, Melbourne Eucalyptus platypus.jpg, '' E. platypus'', showing ‘marlock’ form, Melbourne

Bark

All eucalypts add a layer of bark every year and the outermost layer dies. In about half of the species, the dead bark is shed exposing a new layer of fresh, living bark. The dead bark may be shed in large slabs, in ribbons or in small flakes. These species are known as "smooth barks" and include '' E. sheathiana'', '' E. diversicolor'', '' E. cosmophylla'' and '' E. cladocalyx''. The remaining species retain the dead bark which dries out and accumulates. In some of these species, the fibres in the bark are loosely intertwined (in stringybarks such as '' E. macrorhyncha'' or peppermints such as '' E. radiata'') or more tightly adherent (as in the "boxes" such as '' E. leptophleba''). In some species (the "ironbarks" such as '' E. crebra'' and '' E. jensenii'') the rough bark is infused with gum resin. Many species are ‘half-barks’ or ‘blackbutts’ in which the dead bark is retained in the lower half of the trunks or stems—for example, '' E. brachycalyx'', '' E. ochrophloia'', and '' E. occidentalis''—or only in a thick, black accumulation at the base, as in '' E. clelandii''. In some species in this category, for example '' E. youngiana'' and '' E. viminalis'', the rough basal bark is very ribbony at the top, where it gives way to the smooth upper stems. The smooth upper bark of the half-barks and that of the completely smooth-barked trees and mallees can produce remarkable colour and interest, for example '' E. deglupta''. '' E. globulus'' bark cells are able to photosynthesize in the absence of foliage, conferring an "increased capacity to re-fix internal CO₂ following partial defoliation". This allows the tree to grow in less-than-ideal climates, in addition to providing a better chance of recovery from damage sustained to its leaves in an event such as a fire. Different commonly recognised types of bark include: *

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

—consists of long fibres and can be pulled off in long pieces. It is usually thick with a spongy texture. * Ironbark—is hard, rough, and deeply furrowed. It is impregnated with dried

kino Kino may refer to: Arts, entertainment and media Broadcasters * KINO, a radio station in Arizona, U.S. * Kino FM (98.0 FM – Moscow), a Russian music radio station * KinoTV, now Ruutu+ Leffat ja Sarjat, a Finnish TV channel Fictional entities ...

(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 and can flake off. * Box—has short fibres. Some also show tessellation. * Ribbon—has the bark coming off in long, thin pieces, but is still loosely attached in some places. They can be long ribbons, firmer strips, or twisted curls. Apple box bark.jpg, Bark detail of '' E. angophoroides'', the apple-topped box Eucalyptus deglupta-trees.jpg, Coloured bark of '' E. deglupta'' native to Southeast Asia Eucalyptus bark.jpg, 'Box' bark of '' E. quadrangulata'', the white-topped box Eucalyptus sideroxylon - bark.jpg, Dark, fissured ' ironbark' of '' E. sideroxylon''

Leaves

Nearly all ''Eucalyptus'' are evergreen, but some tropical species lose their leaves at the end of the dry season. As in other members of the myrtle family, ''Eucalyptus'' leaves are covered with oil glands. The copious oils produced are an important feature of the genus. Although mature ''Eucalyptus'' trees may be 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 Petiole may refer to: *Petiole (botany), the stalk of a leaf, attaching the blade to the stem *Petiole (insect anatomy) In entomology, petiole is the technical term for the narrow waist of some hymenopteran insects, especially ants, bees, a ...

, apparently alternate and waxy or glossy green. In contrast, the leaves of seedlings are often opposite, sessile and

glaucous ''Glaucous'' (, ) is used to describe the pale grey or bluish-green appearance of the surfaces of some plants, as well as in the names of birds, such as the glaucous gull (''Larus hyperboreus''), glaucous-winged gull (''Larus glaucescens''), g ...

, but many exceptions to this pattern exist. Many species such as '' E. melanophloia'' and ''E. setosa'' retain the juvenile leaf form even when the plant is reproductively mature. Some species, such as '' E. macrocarpa'', '' E. rhodantha'', and '' E. crucis'', are sought-after ornamentals due to this lifelong juvenile leaf form. A few species, such as '' E. petraea'', '' E. dundasii'', and '' E. lansdowneana'', have shiny green leaves throughout their life cycle. '' E. caesia'' exhibits the opposite pattern of leaf development to most ''Eucalyptus'', with shiny green leaves in the seedling stage and dull, glaucous leaves in mature crowns. The contrast between juvenile and adult leaf phases is valuable in field identification. Four leaf phases are recognised in the development of a ''Eucalyptus'' plant: the ‘seedling’, ‘juvenile’, ‘intermediate’, and ‘adult’ phases. However, no definite transitional point occurs between the phases. The intermediate phase, when the largest leaves are often formed, links the juvenile and adult phases.Brooker & Kleinig (2001) In all except a few species, the leaves form in pairs on opposite sides of a square stem, consecutive pairs being at right angles to each other (decussate). In some narrow-leaved species, for example '' E. oleosa'', the seedling leaves after the second leaf pair are often clustered in a detectable

spiral In mathematics, a spiral is a curve which emanates from a point, moving farther away as it revolves around the point. Helices Two major definitions of "spiral" in the American Heritage Dictionary are: Eucalyptus camaldulensis seeds00

The most readily recognisable characteristics of ''Eucalyptus'' species are the distinctive flowers and fruit (capsules or "gumnuts"). Flowers have numerous fluffy

s which may be white, cream, yellow, pink, or red; in bud, the stamens are enclosed in a cap known as an operculum which is composed of the fused sepals or petals, or both. Thus, flowers have no petals, but instead decorate themselves with the many showy stamens. As the stamens expand, the operculum is forced off, splitting away from the cup-like base of the flower; this is one of the features that unites the genus. The woody fruits or capsules are roughly cone-shaped and have valves at the end which open to release the seeds, which are waxy, rod-shaped, about 1 mm in length, and yellow-brown in colour. Most species do not flower until adult foliage starts to appear; ''E. cinerea'' and ''E. perriniana'' are notable exceptions.

Taxonomy

The genus ''Eucalyptus'' was first formally described in 1789 by Charles Louis L'Héritier de Brutelle who published the description in his book ''Sertum Anglicum, seu, Plantae rariores quae in hortis juxta Londinum'' along with a description of the type species, '' Eucalyptus obliqua''. The name ''Eucalyptus'' is derived from the Ancient Greek words meaning 'good, well, true, beautiful, very' and meaning '(I) cover, conceal, hide' referring to the operculum covering the flower buds. The type specimen was collected in 1777 by David Nelson, the gardener-botanist on Cook's third voyage. He collected the specimen on Bruny Island and sent it to de Brutelle who was working in London at that time.

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 Sir Joseph Banks, 1st Baronet, (19 June 1820) was an English naturalist, botanist, and patron of the natural sciences. Banks made his name on the 1766 natural-history expedition to Newfoundland and Labrador. He took part in Captain James ...

and Daniel Solander arrived at Botany Bay with Captain James Cook. There they collected specimens of ''E. gummifera'' and later, near the Endeavour River in northern ''Queensland'', ''E. platyphylla''; neither of these species was named as such at the time. In 1777, on Cook's third expedition, David Nelson collected a eucalypt on Bruny Island in southern Tasmania. This specimen was taken to the British Museum in London, and was named ''Eucalyptus obliqua'' by the French botanist L'Héritier, who was working in London at the time. He coined the generic name from the Greek roots ''eu'' and ''calyptos'', meaning "well" and "covered" in reference to the operculum of the flower bud which protects the developing flower parts as the flower develops and is shed by the pressure of the emerging stamens at flowering. It was most likely an accident that L'Héritier chose a feature common to all eucalypts. The name ''obliqua'' was derived from the Latin ''obliquus'', meaning "oblique", which is the botanical term describing a leaf base where the two sides of the leaf blade are of unequal length and do not meet the petiole at the same place. ''E. obliqua'' was published in 1788–89, which coincided with the first official European settlement of Australia. Between then and the turn of the 19th century, several more species of ''Eucalyptus'' were named and published. Most of these were by the English botanist James Edward Smith and most were, as might be expected, trees of the

Sydney Sydney ( ) is the capital city of the state of New South Wales, and the most populous city in both Australia and Oceania. Located on Australia's east coast, the metropolis surrounds Sydney Harbour and extends about towards the Blue Mountain ...

region. These include the economically valuable ''E. pilularis'', ''E. saligna'' and ''E. tereticornis''. The first endemic Western Australian ''Eucalyptus'' to be collected and subsequently named was the Yate ('' E. cornuta'') by the French botanist Jacques Labillardière, who collected in what is now the Esperance area in 1792. Several Australian botanists were active during the 19th century, particularly

Ferdinand von Mueller Baron Sir Ferdinand Jacob Heinrich von Mueller, (german: Müller; 30 June 1825 – 10 October 1896) was a German-Australian physician, geographer, and most notably, a botanist. He was appointed government botanist for the then colony of Vict ...

, whose work on ''eucalypts'' contributed greatly to the first comprehensive account of the genus in George Bentham's ''Flora Australiensis'' in 1867. 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 Joseph Henry Maiden (25 April 1859 – 16 November 1925) was a botanist who made a major contribution to knowledge of the Australian flora, especially the genus ''Eucalyptus''. This botanist is denoted by the author abbreviation when citing ...

(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.

Species and hybrids

Over 700 species of ''Eucalyptus'' are known. Some have diverged from the mainstream of the genus to the extent that they are quite isolated genetically and are able to be recognised by only a few relatively invariant characteristics. Most, however, may be regarded as belonging to large or small groups of related species, which are often in geographical contact with each other and between which gene exchange still occurs. In these situations, many species appear to grade into one another, and intermediate forms are common. In other words, some species are relatively fixed genetically, as expressed in their morphology, while others have not diverged completely from their nearest relatives. Hybrid individuals have not always been recognised as such on first collection and some have been named as new species, such as ''E. chrysantha'' (''E. preissiana'' × ''E. sepulcralis'') and ''E.'' "rivalis" (''E. marginata'' × ''E. megacarpa''). Hybrid combinations are not particularly common in the field, but some other published species frequently seen in Australia have been suggested to be hybrid combinations. For example, ''

Eucalyptus × erythrandra ''Eucalyptus × erythrandra'', commonly known as rosebud gum, is a species of mallee or shrub that is endemic to Western Australia. It typically grows to a height of and has smooth grey bark, and pinkish flowers from September to October or J ...

'' 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 ''Eucalyptus'' species, allows chemotaxonomic discrimination in the sections renantheroideae and renantherae and the ratio of the amount of

leucoanthocyanin Leucoanthocyanidin (flavan-3,4-diols) are colorless chemical compounds related to anthocyanidins and anthocyanins. Leucoanthocyanins can be found in ''Anadenanthera peregrina'' and in several species of ''Nepenthes'' including '' N. burbidgeae ...

s varies considerably in certain species.

Related genera

Tasmania logging 16 Styx a tree in danger

''Eucalyptus'' is one of three similar

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...

that are commonly referred to as " eucalypts", the others being ''

'' and ''

Angophora ''Angophora'' is a genus of nine species of trees and shrubs in the myrtle family, Myrtaceae. Endemic to eastern Australia, they differ from other eucalypts in having juvenile and adult leaves arranged in opposite pairs, sepals reduced to projec ...

''. Many species, though by no means all, are known as gum trees because they exude copious

from any break in the

bark Bark may refer to: * Bark (botany), an outer layer of a woody plant such as a tree or stick * Bark (sound), a vocalization of some animals (which is commonly the dog) Places * Bark, Germany * Bark, Warmian-Masurian Voivodeship, Poland Arts, ...

(e.g., scribbly gum). The generic name is derived from the Greek words ευ (''eu'') "well" and καλύπτω (''kalýpto'') "to cover", referring to the operculum on the

calyx Calyx or calyce (plural "calyces"), from the Latin ''calix'' which itself comes from the Ancient Greek ''κάλυξ'' (''kálux'') meaning "husk" or "pod", may refer to: Biology * Calyx (anatomy), collective name for several cup-like structures ...

that initially conceals the flower.

Distribution

There are more than 700 species of ''Eucalyptus'' and most are native to Australia; a very small number are found in adjacent areas of New Guinea and Indonesia. One species, '' Eucalyptus deglupta,'' ranges as far north as the Philippines. Of the 15 species found outside Australia, just nine are exclusively non-Australian. Species of ''Eucalyptus'' are cultivated widely in the tropical and temperate world, including the

Americas The Americas, which are sometimes collectively called America, are a landmass comprising the totality of North and South America. The Americas make up most of the land in Earth's Western Hemisphere and comprise the New World. Along with th ...

, Europe, Africa, the

Mediterranean Basin In biogeography, the Mediterranean Basin (; also known as the Mediterranean Region or sometimes Mediterranea) is the region of lands around the Mediterranean Sea that have mostly a Mediterranean climate, with mild to cool, rainy winters and w ...

, the Middle East,

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

, and the Indian subcontinent. However, the range over which many eucalypts can be planted in the temperate zone is constrained by their limited cold tolerance. Australia is covered by of eucalypt forest, comprising three quarters of the area covered by native forest. The Blue Mountains of southeastern Australia have been a centre of eucalypt diversification; their name is in reference to the blue haze prevalent in the area, believed derived from the volatile terpenoids emitted by these trees.

Fossil record

The oldest definitive ''Eucalyptus'' fossils are from Patagonia in South America, where eucalypts are no longer native, though they have been introduced from Australia. The fossils are from the early Eocene (51.9 Mya), and were found in the

Laguna del Hunco Formation The Laguna del Hunco Formation or Laguna del Hunco Tuff ( es, Formación Laguna del Hunco, Tufolitas Laguna del Hunco) is a localized Early Eocene (Itaboraian in the SALMA classification) fossiliferous geological formation of the Cañadón Asfalto ...

in Chubut Province in Argentina. This shows that the genus had a

Gondwana Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final stages ...

n distribution. Fossil leaves also occur in the Miocene of New Zealand, where the genus is not native today, but again have been introduced from Australia. Despite the prominence of ''Eucalyptus'' in modern Australia, estimated to contribute some 75% of the modern vegetation, the fossil record is very scarce throughout much of the

Cenozoic The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configura ...

, and suggests that this rise to dominance is a geologically more recent phenomenon. The oldest reliably dated macrofossil of ''Eucalyptus'' is a 21-million-year-old tree-stump encased in basalt in the upper Lachlan Valley in New South Wales. Other fossils have been found, but many are either unreliably dated or else unreliably identified.Hill, R. S. "The history of selected Australian taxa." History of the Australian vegetation: Cretaceous to Recent (1994): 390. It is useful to consider where ''Eucalyptus'' fossils have not been found. Extensive research has gone into the fossil floras of the Paleocene to

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...

of South-Eastern Australia, and has failed to uncover a single ''Eucalyptus'' specimen. Although the evidence is sparse, the best hypothesis is that in the mid-Tertiary, the continental margins of Australia only supported more mesic noneucalypt vegetation, and that eucalypts probably contributed to the drier vegetation of the arid continental interior. With the progressive drying out of the continent since the Miocene, eucalypts were displaced to the continental margins, and much of the mesic and rainforest vegetation that was once there was eliminated entirely. The current superdominance of ''Eucalyptus'' in Australia may be an artefact of human influence on its ecology. In more recent sediments, numerous findings of a dramatic increase in the abundance of ''Eucalyptus'' pollen are associated with increased charcoal levels. Though this occurs at different rates throughout Australia, it is compelling evidence for a relationship between the artificial increase of fire frequency with the arrival of Aboriginals and increased prevalence of this exceptionally fire-tolerant genus.

Tall timber

Several eucalypt species are among the

tallest trees This is a list of the tallest known species of trees, as reflected by measurements of the tallest reliably-measured individual specimen. Although giant trees grow in both tropical and temperate regions, they are very restricted geographically and ...

in the world. '' Eucalyptus regnans'', the Australian 'mountain ash', is the tallest of all flowering plants (

angiosperm Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

s); today, the tallest measured specimen named

Centurion A centurion (; la, centurio , . la, centuriones, label=none; grc-gre, κεντυρίων, kentyríōn, or ) was a position in the Roman army during classical antiquity, nominally the commander of a century (), a military unit of around 80 ...

is tall. Coast Douglas-fir is about the same height; only coast redwood is taller, and they are

conifer Conifers are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single ...

s ( gymnosperms). Six other eucalypt species exceed 80 metres in height: '' Eucalyptus obliqua'', ''

Eucalyptus delegatensis ''Eucalyptus'' () is a genus of over seven hundred species of flowering trees, shrubs or mallees in the myrtle family, Myrtaceae. Along with several other genera in the tribe Eucalypteae, including '' Corymbia'', they are commonly known as euca ...

'', '' Eucalyptus diversicolor'', ''

Eucalyptus nitens ''Eucalyptus nitens'', commonly known as shining gum or silvertop, is a species of tall tree native to Victoria and eastern New South Wales. It has smooth greyish bark, sometimes with thin, rough bark near the base, lance-shaped adult leaves, flo ...

'', '' Eucalyptus globulus'' and '' Eucalyptus viminalis''.

Frost intolerance

Most eucalypts are not tolerant of severe cold. Eucalypts do well in a range of climates but are usually damaged by anything beyond a light frost of ; the hardiest are the snow gums, such as ''

Eucalyptus pauciflora ''Eucalyptus pauciflora'', commonly known as snow gum, cabbage gum or white sally, is a species of tree or mallee that is native to eastern Australia. It has smooth bark, lance-shaped to elliptical leaves, flower buds in clusters of between sev ...

'', which is capable of withstanding cold and frost down to about . Two subspecies, ''E. pauciflora subsp. niphophila'' and ''E. pauciflora subsp. debeuzevillei'' in particular are even hardier and can tolerate even quite severe winters. Several other species, especially from the high plateau and mountains of central Tasmania such as '' Eucalyptus coccifera'', ''

Eucalyptus subcrenulata ''Eucalyptus subcrenulata'', commonly known as Tasmanian alpine yellow gum, is a species of small to medium-sized tree that is endemic to the highlands of Tasmania. It has smooth bark, glossy green, lance-shaped to egg-shaped adult leaves, flow ...

'' and ''

Eucalyptus gunnii ''Eucalyptus gunnii'', commonly known as cider gum, is a species of small to medium-sized tree endemic to the island of Tasmania, Australia. It has mostly smooth bark, lance-shaped to egg-shaped adult leaves, flower buds in groups of three, whi ...

'', have also produced extreme cold-hardy forms and it is seed procured from these genetically hardy strains that are planted for ornament in colder parts of the world.

Animal relationships

extracted from ''Eucalyptus'' leaves contains compounds that are powerful natural disinfectants and can be toxic in large quantities. Several

marsupial herbivore Diprotodontia (, from Greek "two forward teeth") is the largest extant order of marsupials, with about 155 species, including the kangaroos, wallabies, possums, koala, wombats, and many others. Extinct diprotodonts include the hippopotamus-size ...

s, notably koalas and some

possums Possum may refer to: Animals * Phalangeriformes, or possums, any of a number of arboreal marsupial species native to Australia, New Guinea, and Sulawesi ** Common brushtail possum (''Trichosurus vulpecula''), a common possum in Australian urban a ...

, are relatively tolerant of it. The close correlation of these oils with other more potent toxins called formylated phloroglucinol compounds ( euglobals, macrocarpals and sideroxylonals) allows koalas and other marsupial species to make food choices based on the smell of the leaves. For koalas, these compounds are the most important factor in leaf choice. ''Eucalyptus'' flowers produce a great abundance of

nectar Nectar is a sugar-rich liquid produced by plants in glands called nectaries or nectarines, either within the flowers with which it attracts pollinating animals, or by extrafloral nectaries, which provide a nutrient source to animal mutualists ...

, providing food for many

pollinator A pollinator is an animal that moves pollen from the male anther of a flower to the female stigma of a flower. This helps to bring about fertilization of the ovules in the flower by the male gametes from the pollen grains. Insects are the maj ...

s including insects, birds,

bats Bats are mammals of the order Chiroptera.''cheir'', "hand" and πτερόν''pteron'', "wing". With their forelimbs adapted as wings, they are the only mammals capable of true and sustained flight. Bats are more agile in flight than most bi ...

and

. Many lizard species in Australia feed on ''Eucalyptus'' sap as well, famously in the case of the Dubious dtella. Although ''Eucalyptus'' trees are seemingly well-defended from herbivores by the oils and phenolic compounds, they have insect pests. These include the eucalyptus longhorn borer ''

Phoracantha semipunctata ''Phoracantha semipunctata'', the Australian Eucalyptus longhorn, is a species of beetle in the family Cerambycidae. Native to Australia, it has now spread to many parts of the world, including practically all countries where tree species of '' ...

'' and the aphid-like psyllids that

create To create is to make a new person, place, thing, or phenomenon. The term and its variants may also refer to: * Creativity, phenomenon whereby something new and valuable is created Art, entertainment, and media * Create (TV network), an America ...

"bell lerps", both of which have become established as pests throughout the world wherever eucalypts are cultivated. The eusocial beetle '' Austroplatypus incompertus'' makes and defends its galleries exclusively inside ''Eucalyptus'' plants. The trunks and branches of the ''Eucalyptus'' tree allow the largest known moth, ''Zelotypia stacyi'' (the bentwing ghost moth, having a wingspan up to 250 mm) to feed and protect their larva and pupa, respectively.

Adaptation to fire

Eucalypts originated between 35 and 50 million years ago, not long after

Australia-New Guinea The continent of Australia, sometimes known in technical contexts by the names Sahul (), Australia-New Guinea, Australinea, Meganesia, or Papualand to distinguish it from the country of Australia, is located within the Southern and East ...

separated from

, their rise coinciding with an increase in fossil charcoal deposits (suggesting that fire was a factor even then), but they remained a minor component of the Tertiary rainforest until about 20 million years ago, when the gradual drying of the continent and depletion of soil nutrients led to the development of a more open forest type, predominantly '' Casuarina'' and ''

Acacia ''Acacia'', commonly known as the wattles or acacias, is a large genus of shrubs and trees in the subfamily Mimosoideae of the pea family Fabaceae. Initially, it comprised a group of plant species native to Africa and Australasia. The genus na ...

'' species. The two valuable timber trees, alpine ash '' E. delegatensis'' and Australian mountain ash '' E. regnans'', are killed by fire and only regenerate from seed. The same 2003 bushfire that had little impact on forests around

Canberra Canberra ( ) is the capital city of Australia. Founded following the federation of the colonies of Australia as the seat of government for the new nation, it is Australia's largest inland city and the eighth-largest city overall. The ci ...

resulted in thousands of hectares of dead ash forests. However, a small amount of ash survived and put out new ash trees as well.

Fire hazard

''Eucalyptus'' oil is highly flammable; ignited trees have been known to explode. Bushfires can travel easily through the oil-rich air of the tree crowns. Eucalypts obtain long-term fire survivability from their ability to regenerate from

situated deep within their thick bark, or from lignotubers, or by producing serotinous 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 high in phenolics, preventing its breakdown by fungi and thus accumulating as large amounts of dry, combustible fuel.Reid, J.B. & Potts, B.M. (2005). Eucalypt Biology. In: Reid ''et al.'' (eds.) Vegetation of Tasmania., pp. 198-223. Australian Government. Consequently, dense eucalypt plantings may be subject to catastrophic firestorms. In fact, almost thirty years before the Oakland firestorm of 1991, 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 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. During World War II, one California town cut down their ''Eucalyptus'' trees to “about a third of their height in the vicinity of anti-aircraft guns” because of the known fire-fueling qualities of the trees, with the mayor telling a newspaper reporter, “If a shell so much as hits a leaf, it’s supposed to explode.”

Falling branches

Fallen Eucalyptus camaldulensis limbs (1)

Some species of ''Eucalyptus'' drop branches unexpectedly. In Australia,

Parks Victoria Parks Victoria is a government agency of the state of Victoria, Australia. Parks Victoria was established in December 1996 as a statutory authority, reporting to the Victorian Minister for Environment and Climate Change. The ''Parks Victoria Ac ...

warns campers not to camp under river red gums. Some councils in Australia such as Gosnells, Western Australia, 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. Although all large trees can drop branches, the density of ''Eucalyptus'' wood is high due to its high resin content, increasing the hazard.

Cultivation and uses

Eucalyptus niphophila - Mount Ginini - Namadgi National Park

Eucalypts were introduced from

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

to the rest of the world following the

Cook Cook or The Cook may refer to: Food preparation * Cooking, the preparation of food * Cook (domestic worker), a household staff member who prepares food * Cook (professional), an individual who prepares food for consumption in the food industry * ...

expedition in 1770. Collected by Sir Joseph Banks,

botanist Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Ancient Greek wo ...

on the expedition, they were subsequently introduced to many parts of the world, notably California, southern Europe, Africa, the Middle East, South Asia and South America. About 250 species are under cultivation in California. In Portugal and also Spain, ''eucalypts'' have been grown in plantations for the production of

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

invasive Invasive may refer to: *Invasive (medical) procedure *Invasive species *Invasive observation, especially in reference to surveillance *Invasively progressive spread of disease from one organ in the body to another, especially in reference to cancer ...

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 () is the social science that studies the production, distribution, and consumption of goods and services. Economics focuses on the behaviour and interactions of economic agents and how economies work. Microeconomics analyzes ...

important trees, and they have become a

cash crop A cash crop or profit crop is an Agriculture, agricultural crop which is grown to sell for profit. It is typically purchased by parties separate from a farm. The term is used to differentiate marketed crops from staple crop (or "subsistence crop") ...

in poor areas such as Timbuktu, Mali WorldWatch Institute. (2007) '' State of the World: Our Urban Future''. and the Peruvian Andes,Luzar J. (2007). The Political Ecology of a "Forest Transition": Eucalyptus forestry in the Southern Peruvian. ''Ethnobotany Research & Applications''. despite concerns that the trees are

in some environments like those of South Africa. Best-known are perhaps the varieties

karri ''Eucalyptus diversicolor'', commonly known as karri, is a species of flowering plant in the family Myrtaceae and is Endemism, endemic to the Southwest Australia, south-west of Western Australia. It is a tall tree with smooth light grey to cre ...

and yellow box. Due to their fast growth, the foremost benefit of these trees is their wood. They can be chopped off at the root and grow back again. They provide many desirable characteristics for use as

ornament An ornament is something used for decoration. Ornament may also refer to: Decoration * Ornament (art), any purely decorative element in architecture and the decorative arts * Biological ornament, a characteristic of animals that appear to serve ...

, timber, firewood and pulpwood. Eucaplytus wood is also used in a number of industries, from fence posts (where the oil-rich wood's high resistance to decay is valued) and charcoal to cellulose extraction for

biofuel Biofuel is a fuel that is produced over a short time span from biomass, rather than by the very slow natural processes involved in the formation of fossil fuels, such as oil. According to the United States Energy Information Administration (E ...

s. Fast growth also makes eucalypts suitable as windbreaks and to reduce erosion. Some ''Eucalyptus'' species have attracted attention from horticulturists, global development researchers, and environmentalists because of desirable traits such as being fast-growing sources of wood, producing oil that can be used for cleaning and as a natural

insecticide Insecticides are substances used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. Insecticides are used in agriculture, medicine, industry and by consumers. Insecticides are claimed to b ...

, or an ability to be used to drain

swamp A swamp is a forested wetland.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p. Swamps are considered to be transition zones because both land and water play a role in ...

s and thereby reduce the risk of malaria. Eucalyptus oil finds many uses like in fuels, fragrances, insect repellence and antimicrobial activity. ''Eucalyptus'' trees show

allelopathic Allelopathy is a biological phenomenon by which an organism produces one or more biochemicals that influence the germination, growth, survival, and reproduction of other organisms. These biochemicals are known as allelochemicals and can have ben ...

effects; they release compounds which inhibit other plant species from growing nearby. Outside their natural ranges, eucalypts are both lauded for their beneficial economic impact on poor populations and criticised for being "water-guzzling"

aliens Alien primarily refers to: * Alien (law), a person in a country who is not a national of that country ** Enemy alien, the above in times of war * Extraterrestrial life, life which does not originate from Earth ** Specifically, intelligent extrate ...

, leading to controversy over their total impact. Eucalypts draw a tremendous amount of water from the soil through the process of transpiration. They have been planted (or re-planted) in some places to lower the water table and reduce

soil salination Soil salinity is the salt content in the soil; the process of increasing the salt content is known as salinization. Salts occur naturally within soils and water. Salination can be caused by natural processes such as mineral weathering or by the ...

. Eucalypts have also been used as a way of reducing malaria by draining the soil in Algeria, Lebanon, Sicily, elsewhere in Europe, in the Caucasus (Western Georgia), and California. Drainage removes

s which provide a habitat for mosquito larvae, but can also destroy ecologically productive areas. This drainage is not limited to the soil surface, because the ''Eucalyptus'' roots are up to in length and can, depending on the location, even reach the phreatic zone.

Pulpwood

''Eucalyptus'' is the most common short fibre source for

to make pulp. The types most often used in

papermaking Papermaking is the manufacture of paper and cardboard, which are used widely for printing, writing, and packaging, among many other purposes. Today almost all paper is made using industrial machinery, while handmade paper survives as a speciali ...

are '' Eucalyptus globulus'' (in temperate areas) and the ''

Eucalyptus urophylla ''Eucalyptus urophylla'', commonly known as Timor white gum, Timor mountain gum, popo or ampupu, is a species of eucalypt native to islands of the Indonesian Archipelago and Timor. It is also common in other countries with humid and subhumid tr ...

'' x ''

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. At maturity, it reaches tall, though the largest specimens can exceed tall. It is f ...

'' hybrid (in the tropics). 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 or opaque may refer to: * Impediments to (especially, visible) light: ** Opacities, absorption coefficients ** Opacity (optics), property or degree of blocking the transmission of light * Metaphors derived from literal optics: ** In lingu ...

that are important for all types of

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 Fine papers are normally surface sized or pigmente ...

s. The low coarseness is important for high quality

coated paper Coated paper (also known as enamel paper, gloss paper, and thin paper) is paper that has been coated by a mixture of materials or a polymer to impart certain qualities to the paper, including weight, surface gloss, smoothness, or reduced ink absor ...

s. ''Eucalyptus'' is suitable for many tissue papers as the short and slender fibres gives a high number of fibres per gram and low coarseness contributes to softness.

''Eucalyptus'' oil

Eucalyptus oil is readily steam distilled from the leaves and can be used for cleaning and as an industrial solvent, as an antiseptic, for deodorising, and in very small quantities in

food Food is any substance consumed by an organism for nutritional support. Food is usually of plant, animal, or fungal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is inge ...

supplements, especially sweets, cough drops, toothpaste and decongestants. It has insect-repellent properties, and serves as an active ingredient in some commercial mosquito-repellents. Aromatherapists have adopted ''Eucalyptus'' oils for a wide range of purposes. '' Eucalyptus globulus'' is the principal source of ''Eucalyptus'' oil worldwide.

Musical instruments

Eucalypt wood is also commonly used to make

didgeridoo The didgeridoo (; also spelt didjeridu, among other variants) is a wind instrument, played with vibrating lips to produce a continuous drone while using a special breathing technique called circular breathing. The didgeridoo was developed by ...

s, a traditional Australian Aboriginal wind instrument. The trunk of the tree is hollowed out by termites, and then cut down if the bore is of the correct size and shape.

Dyes

All parts of ''Eucalyptus'' may be used to make

dye A dye is a colored substance that chemically bonds to the substrate to which it is being applied. This distinguishes dyes from pigments which do not chemically bind to the material they color. Dye is generally applied in an aqueous solution an ...

s that are substantive on protein fibres (such as silk and wool), simply by processing the plant part with water. Colours to be achieved range from yellow and orange through green, tan, chocolate and deep rust red. The material remaining after processing can be safely used as mulch or fertiliser.

Prospecting

''Eucalyptus'' trees in the Australian outback draw up gold from tens of metres underground through their root system and deposit it as particles in their leaves and branches. A Maia detector for x-ray elemental imaging at the

Australian Synchrotron ANSTO's Australian Synchrotron is a 3 GeV national synchrotron radiation facility located in Clayton, in the south-eastern suburbs of Melbourne, Victoria, which opened in 2007. ANSTO's Australian Synchrotron is a light source facility (in cont ...

clearly showed deposits of gold and other metals in the structure of ''Eucalyptus'' leaves from the Kalgoorlie region of Western Australia that would have been untraceable using other methods. The microscopic leaf-bound "nuggets", about 8 micrometres wide on average, are not worth collecting themselves, but may provide an environmentally benign way of locating subsurface mineral deposits.

''Eucalyptus'' as plantation species

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 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 El Dorado (, ; Spanish for "the golden"), originally ''El Hombre Dorado'' ("The Golden Man") or ''El Rey Dorado'' ("The Golden King"), was the term used by the Spanish in the 16th century to describe a mythical tribal chief (''zipa'') or king o ...

" of forestry. Today, ''Eucalyptus'' is the most widely planted type of tree in plantations around the world, in South America (mainly in Brazil, Argentina, Paraguay and Uruguay), South Africa,

, India,

Galicia Galicia may refer to: Geographic regions * Galicia (Spain), a region and autonomous community of northwestern Spain ** Gallaecia, a Roman province ** The post-Roman Kingdom of the Suebi, also called the Kingdom of Gallaecia ** The medieval King ...

, Portugal and many more.

North America

;California In the 1850s, ''Eucalyptus'' trees were introduced to California by Australians during the

California Gold Rush The California Gold Rush (1848–1855) was a gold rush that began on January 24, 1848, when gold was found by James W. Marshall at Sutter's Mill in Coloma, California. The news of gold brought approximately 300,000 people to California fro ...

. Much of California is similar in 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 railway sleepers. 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 A rail fastening system is a means of fixing rails to railroad ties (North America) or sleepers (British Isles, Australasia, and Africa). The terms ''rail anchors'', ''tie plates'', ''chairs'' and ''track fasteners'' are used to refer to part ...

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.

The species '' Eucalyptus rostrata, E. tereticornas,'' and '' E. cladocalyx'' are all present in California, but the blue gum '' E. globulus'' makes up by far the largest population in the state. One way in which the ''Eucalyptus'', mainly the blue gum '' E. globulus'', proved valuable in California was in providing windbreaks for highways, orange groves, and 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'' plantations in California have been criticised, because they compete with native plants and typically do not support native animals. ''Eucalyptus'' has historically been planted to replace California's coast live oak population, and the new ''Eucalyptus'' is not as hospitable to native flora and fauna as the oaks. In appropriately foggy conditions on the California Coast, ''Eucalyptus'' can spread at a rapid rate. The absence of natural inhibitors such as the koala or pathogens native to Australia have aided in the spread of California ''Eucalyptus'' trees. This is not as big of an issue further inland, but on the coast invasive eucalypts can disrupt native ecosystems. ''Eucalyptus'' may have adverse effects on local streams due to their chemical composition, and their dominance threatens species that rely on native trees. Nevertheless, some native species have been known to adapt to the ''Eucalyptus'' trees. Notable examples are

heron The herons are long-legged, long-necked, freshwater and coastal birds in the family Ardeidae, with 72 recognised species, some of which are referred to as egrets or bitterns rather than herons. Members of the genera ''Botaurus'' and ''Ixobrychus ...

s, great horned owl, and the

monarch butterfly The monarch butterfly or simply monarch (''Danaus plexippus'') is a milkweed butterfly (subfamily Danainae) in the family Nymphalidae. Other common names, depending on region, include milkweed, common tiger, wanderer, and black-veined brown. It ...

using ''Eucalyptus'' groves as habitat. Despite these successes, eucalypts generally has a net negative impact on the overall balance of the native ecosystem. Fire is also a problem. Eucalypts has been noted for their flammable properties and the large fuel loads in the understory of eucalypt forests. ''Eucalyptus'' trees were a catalyst for the spread of the 1923 fire in Berkeley, which destroyed 568 homes. The 1991

Oakland Hills firestorm : The Oakland firestorm of 1991 was a large suburban wildland–urban interface conflagration that occurred on the hillsides of northern Oakland, California, and southeastern Berkeley over the weekend of October 19–20, 1991, before being ...

, which caused US$1.5 billion in damage, destroyed almost 3,000 homes, and killed 25 people, was partly fueled by large numbers of eucalypts close to the houses. Despite these issues, there are calls to preserve the ''Eucalyptus'' plants in California. Advocates for the tree claim its fire risk has been overstated. Some even claim that the ''Eucalyptus's'' absorption of moisture makes it a barrier against fire. These experts believe that the herbicides used to remove the ''Eucalyptus'' would negatively impact the ecosystem, and the loss of the ''Eucalypti'' would release carbon into the atmosphere unnecessarily. There is also an aesthetic argument for keeping the ''Eucalyptus''; the trees are viewed by many as an attractive and iconic part of the California landscape. Many say that although the tree is not native, it has been in California long enough to become an essential part of the ecosystem and therefore should not be attacked as invasive. These arguments have caused experts and citizens in California and the

Bay Area The San Francisco Bay Area, often referred to as simply the Bay Area, is a populous region surrounding the San Francisco, San Pablo, and Suisun Bay estuaries in Northern California. The Bay Area is defined by the Association of Bay Area Gov ...

to debate the merits of ''Eucalyptus'' removal versus preservation. However, the general consensus remains that some areas urgently require ''Eucalyptus'' management to stave off potential fire hazards. Efforts to remove some of California's ''Eucalyptus'' trees have been met with a mixed reaction from the public, and there have been protests against removal. Removing ''Eucalyptus'' trees can be expensive and often requires machinery or the use of herbicides. The trees struggle to reproduce on their own outside of the foggy regions of Coastal California, and therefore some inland ''Eucalyptus'' forests are predicted to die out naturally. In some parts of California, eucalypt plantations 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. Certain ''Eucalyptus'' species may also be grown for ornament in warmer parts of the Pacific Northwest—western Washington, western Oregon and southwestern British Columbia.

South America

;Argentina It was introduced in Argentina around 1870 by President

Domingo F. Sarmiento Domingo Faustino Sarmiento (; born Domingo Faustino Fidel Valentín Sarmiento y Albarracín; 15 February 1811 – 11 September 1888) was an Argentine activist, intellectual, writer, statesman and the second President of Argentina. His writing sp ...

, who had brought the seeds from Australia and it quickly became very popular. The most widely planted species were '' E. globulus'', '' E. viminalis'' and '' E. rostrata''. Currently, the

Humid Pampas The Humid Pampas ( es, Pampa Húmeda) is an extensive ecoregion of flat, fertile grassland of loessic origin in Argentina. It has a precipitation average of 900 mm per year, in contrast with the Dry Pampas to the west, which average less than ...

region has small forests and ''Eucalyptus'' barriers, some up to 80 years old, about 50 meters high and a maximum of one meter in diameter. ;Uruguay Antonio Lussich introduced ''Eucalyptus'' into Uruguay in approximately 1896, throughout what is now Maldonado Department, and it has spread all over the south-eastern and eastern coast. There had been no trees in the area because it consisted of dry sand dunes and stones. Lussich also introduced many other trees, particularly ''

'' and pines, but they have not expanded so extensively. Uruguayan forestry crops using ''Eucalyptus'' species have been promoted since 1989, when the new National Forestry Law established that 20% of the national territory would be dedicated to forestry. As the main landscape of Uruguay is grassland (140,000 km², 87% of the national territory), most of the forestry plantations would be established in prairie regions.Perez-Arrarte, C., 1993. Desarrollo forestal y medio ambiente (compilation). CIEDUR Montevideo, Uruguay The planting of ''Eucalyptus'' sp. has been criticised because of concerns that soil would be degraded by

nutrient depletion Nutrient depletion is a form of resource depletion and refers to the loss of nutrients and micronutrients in a habitat or parts of the biosphere, most often the soil (soil depletion, soil degradation). On the level of a complete ecological niche or ...

and other biological changes.Caffera, R.M., Cespedes, C., Gonzalez, A., Gutierrez, M.O., Panario, D.H., 1991. Hacia una evaluacion de efectos ambientales de la forestacion en Uruguay con especies introducidas. CIEDUR, Montevideo, Uruguay. During the last ten years, in the northwestern regions of Uruguay the ''Eucalyptus'' sp. plantations have reached annual forestation rates of 300%. That zone has a potential forested area of 1 million hectares, approximately 29% of the national territory dedicated to forestry, of which approximately 800,000 hectares are currently forested by monoculture of ''Eucalyptus'' spp. It is expected that the radical and durable substitution of vegetation cover leads to changes in the quantity and quality of

soil organic matter Soil organic matter (SOM) is the organic matter component of soil, consisting of plant and animal detritus at various stages of decomposition, cells and tissues of soil microbes, and substances that soil microbes synthesize. SOM provides numerous b ...

. Such changes may also influence

soil fertility Soil fertility refers to the ability of soil to sustain agricultural plant growth, i.e. to provide plant habitat and result in sustained and consistent yields of high quality.

and soil physical and chemical properties. The soil quality effects associated with ''Eucalyptus'' sp. plantations could have adverse effects on soil chemistry; for example: soil acidification, iron leaching,

activities and a high C:N ratio of litter. Additionally, as most scientific understanding of land cover change effects is related to ecosystems where forests were replaced by grasslands or crops, or grassland was replaced by crops, the environmental effects of the current Uruguayan land cover changes are not well understood. The first scientific publication on soil studies in western zone tree plantations (focused on pulp production) appeared in 2004 and described soil acidification and soil carbon changes, similar to a

podzolisation In soil science, podzols are the typical soils of coniferous or boreal forests and also the typical soils of eucalypt forests and heathlands in southern Australia. In Western Europe, podzols develop on heathland, which is often a construct of huma ...

process, and destruction of clay (illite-like minerals), which is the main reservoir of potassium in the soil. Although these studies were carried out in an important zone for forest cultivation, they cannot define the current situation in the rest of the land area under eucalyptus cultivation. Moreover, recently Jackson and Jobbagy have proposed another adverse environmental impact that may result from ''Eucalyptus'' culture on prairie soils—stream acidification. The ''Eucalyptus'' species most planted are ''E. grandis'', ''E. globulus'' and ''E. dunnii''; they are used mainly for pulp mills. Approximately 80,000 ha of ''E. grandis'' situated in the departments of Rivera, Tacuarembó and Paysandú is primarily earmarked for the solid wood market, although a portion of it is used for sawlogs and plywood. The current area under commercial forest plantation is 6% of the total. The main uses of the wood produced are elemental chlorine free pulp mill production (for cellulose and paper),

sawlog The term sawlog is a log of suitable size for sawing into lumber, processed at a sawmill. This is in contrast to those other parts of the stem that are designated pulpwood. Sawlogs will be greater in diameter, straighter and have a lower knot freque ...

plywood Plywood is a material manufactured from thin layers or "plies" of wood veneer that are glued together with adjacent layers having their wood grain rotated up to 90 degrees to one another. It is an engineered wood from the family of manufactured ...

and

bioenergy Biomass is plant-based material used as a fuel for heat or electricity production. It can be in the form of wood, wood residues, energy crops, agricultural residues, and waste from industry, farms, and households. Some people use the terms biom ...

(

thermoelectric The thermoelectric effect is the direct conversion of temperature differences to electric voltage and vice versa via a thermocouple. A thermoelectric device creates a voltage when there is a different temperature on each side. Conversely, when ...

generation). Most of the products obtained from sawmills and

pulp mill A pulp mill is a manufacturing facility that converts wood chips or other plant fiber sources into a thick fiber board which can be shipped to a paper mill for further processing. Pulp can be manufactured using mechanical, semi-chemical, or ful ...

s, as well as plywood and logs, are exported. This has raised the income of this sector with respect to traditional products from other sectors. Uruguayan forestry plantations have rates of growth of 30 cubic metres per hectare per year and commercial harvesting occurs after nine years. ;Brazil Plantação de Eucalipto, Parque do Itaim - Taubaté

Plantação de Eucalipto, Parque do Itaim - Taubaté

Eucalypts were introduced to Brazil in 1910, for timber substitution and the

charcoal Charcoal is a lightweight black carbon residue produced by strongly heating wood (or other animal and plant materials) in minimal oxygen to remove all water and volatile constituents. In the traditional version of this pyrolysis process, cal ...

industry. It has thrived in the local environment, and today there are around 7 million hectares planted. The wood is highly valued 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 plantation soils can sustain endless replanting. ''Eucalyptus'' plantings are also used as wind breaks. 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 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'' round wood 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

; 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 Thomson may refer to: Names * Thomson (surname), a list of people with this name and a description of its origin * Thomson baronets, four baronetcies created for persons with the surname Thomson Businesses and organizations * SGS-Thomson Mic ...

, Greenwood Management or cellulose producers such as

Aracruz Cellulose Aracruz may refer to: * Aracruz Celulose, a Brazilian manufacturer of pulp and paper * Aracruz, Espírito Santo, a municipality in the state of Espírito Santo, Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Por ...

and Stora Enso. Overall, South America was expected to produce 55% of the world's ''Eucalyptus'' round-wood by 2010. Many environmental NGOs have criticised the use of exotic tree species for forestry in Latin America.

Africa

;Ethiopia Eucalypts were introduced to Ethiopia in either 1894 or 1895, either by Emperor Menelik II's French advisor Mondon-Vidailhet or by the Englishman Captain O'Brian. Menelik II endorsed its planting around his new capital city of Addis Ababa because of the massive deforestation around the city for

firewood Firewood is any wooden 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, compared to other forms of wood fuel like pellets or chips. Firewood can ...

. 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 Markos ( am, ደብረ ማርቆስ, Däbrä Marḳos lit: ''Mount of St. Mark'') is a city, separate woreda, and administrative seat of the East Gojjam Zone in Amhara Region, Ethiopia. Etymology Originally named Manqwarar (lit: Cold Place ...

. Pankhurst reports that the most common species found in Addis Ababa in the mid-1960s was '' E. globulus'', although he also found '' E. melliodora'' and '' E. rostrata'' in significant numbers. David Buxton, writing of central Ethiopia in the mid-1940s, observed that eucalyptus trees "have become an integral -- and a pleasing -- element in the Shoan landscape and has largely displaced the slow-growing native 'cedar' ('' Juniperus procera'')." 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 ''Morus'', a genus of flowering plants in the family Moraceae, consists of diverse species of deciduous trees commonly known as mulberries, growing wild and under cultivation in many temperate world regions. Generally, the genus has 64 identif ...

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. ;South Africa Numerous ''Eucalyptus'' species have been introduced into South Africa, mainly for timber and

but also for ornamental purposes. They are popular with beekeepers for the

they provide.Palgrave, K. C. 2002: ''Trees of Southern Africa''. Struik Publishers, Cape Town. 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'' seedlings are usually unable to compete with the indigenous grasses, but after a fire when the grass cover has been removed, a seed-bed may be created. The following ''Eucalyptus'' species have been able to become naturalised in South Africa: '' E. camaldulensis'', '' E. cladocalyx'', '' E. diversicolor'', '' E. grandis'' and '' E. lehmannii''. ;Zimbabwe As in South Africa, many ''Eucalyptus'' species have been introduced into Zimbabwe, mainly for timber and firewood, and '' E. robusta'' and '' E. tereticornis'' have been recorded as having become naturalised there.

Europe

Portugal

Eucalypts have been grown in Portugal since the mid 19th century, the first thought to be a specimen of '' E. obliqua'' introduced to Vila Nova de Gaia in 1829. First as an ornamental but soon after in plantations, these eucalypts are prized due to their long and upright trunks, rapid growth and the ability to regrow after cutting. These plantations now occupy around 800,000 hectares, 10% of the country's total land area, 90% of the trees being '' E. globulus''. As of the late 20th century, there were an estimated 120 species of ''Eucalyptus'' in Portugal. The genus has also been subject to various controversies. Despite representing a large part of the agricultural economy, eucalypt plantations have a negative impact on soil destruction, inducing resistance to water infiltration and increasing the risks of erosion and soil loss, they are highly inflamable, aggravating the risk for wildfires. Various Portuguese laws on eucalypt plantations have been formed and reformed to better suit both sides. There are various ''Eucalyptus'' species of public interest in Portugal, namely a

Karri ''Eucalyptus diversicolor'', commonly known as karri, is a species of flowering plant in the family Myrtaceae and is Endemism, endemic to the Southwest Australia, south-west of Western Australia. It is a tall tree with smooth light grey to cre ...

in Coimbra's Mata Nacional de Vale de Canas, considered to be Europe's tallest tree at high.

Italy

In Italy, the ''Eucalyptus'' only arrived at the turn of the 19th century and large scale plantations were started at the beginning of the 20th century with the aim of drying up swampy ground to defeat malaria. During the 1930s,

Benito Mussolini Benito Amilcare Andrea Mussolini (; 29 July 188328 April 1945) was an Italian politician and journalist who founded and led the National Fascist Party. He was Prime Minister of Italy from the March on Rome in 1922 until his deposition in 194 ...

had thousands of ''Eucalyptus'' planted in the marshes around Rome. This, their rapid growth in the Italian climate and excellent function as windbreaks, has made them a common sight in the south of the country, including the islands of Sardinia and Sicily. They are also valued for the characteristic smelling and tasting

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

Greece

In Greece, eucalypts are widely found, especially in southern Greece and Crete. They are cultivated and used for various purposes, including as an ingredient in pharmaceutical products (e.g., creams, elixirs and sprays) and for leather production. They were imported in 1862 by botanist Theodoros Georgios Orphanides. The principal species is ''Eucalyptus globulus''.

Ireland

''Eucalyptus'' has been grown in Ireland since trials in the 1930s and now grows wild in South Western Ireland in the mild climate.

Asia

''Eucalyptus'' seeds of the species ''E. globulus'' were imported into

Palestine __NOTOC__ Palestine may refer to: * State of Palestine, a state in Western Asia * Palestine (region), a geographic region in Western Asia * Palestinian territories, territories occupied by Israel since 1967, namely the West Bank (including East ...

in the 1860s, but did not acclimatise well. Later, ''E. camaldulensis'' was introduced more successfully and it is still a very common tree in Israel. The use of ''Eucalyptus'' trees to drain swampy land was a common practice in the late nineteenth and early twentieth centuries. The German Templer colony of Sarona had begun planting ''Eucalyptus'' for this purpose by 1874, though it is not known where the seeds came from. Many Zionist colonies also adopted the practice in the following years under the guidance of the Mikveh Israel Agricultural School. ''Eucalyptus'' trees are now considered an

invasive species An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species ad ...

in the region. In India, the Institute of Forest Genetics and Tree Breeding, Coimbatore started a ''Eucalyptus'' breeding program in the 1990s. The organisation released four varieties of conventionally bred, high yielding and genetically improved clones for commercial and research interests in 2010. ''Eucalyptus'' trees were introduced to

Sri Lanka Sri Lanka (, ; si, ශ්‍රී ලංකා, Śrī Laṅkā, translit-std=ISO (); ta, இலங்கை, Ilaṅkai, translit-std=ISO ()), formerly known as Ceylon and officially the Democratic Socialist Republic of Sri Lanka, is an ...

in the late 19th century by tea and coffee planters, for wind protection, shade and fuel. Forestry replanting of ''Eucalyptus'' began in the 1930s in deforested mountain areas, and currently there are about 10 species present in the island. They account for 20% of major reforestation plantings. They provide railway sleepers, utility poles, sawn timber and fuelwood, but are controversial because of their adverse effect on biodiversity, hydrology and soil fertility. They are associated with another invasive species, the eucalyptus gall wasp, ''

Leptocybe ''Leptocybe invasa'', the blue gum chalcid wasp or eucalyptus gall wasp, is a chalcid wasp which is the only species in the monotypic genus ''Leptocybe'' in the subfamily Tetrastichinae, of the family Eulophidae. It is a gall wasp which causes the ...

invasa''.

Pacific Islands

In Hawaii, some 90 species of ''Eucalyptus'' have been introduced to the islands, where they have displaced some native species due to their higher maximum height, fast growth and lower water needs. Particularly noticeable is the rainbow eucalyptus ('' Eucalyptus deglupta''), native to Indonesia and the Philippines, whose bark falls off to reveal a trunk that can be green, red, orange, yellow, pink and purple.

Non-native ''Eucalyptus'' and biodiversity

Due to similar favourable climatic conditions, ''Eucalyptus'' plantations have often replaced oak woodlands, for example in California, Spain and Portugal. The resulting monocultures have raised concerns about loss of biological diversity, through loss of

acorn The acorn, or oaknut, is the nut of the oaks and their close relatives (genera ''Quercus'' and '' Lithocarpus'', in the family Fagaceae). It usually contains one seed (occasionally two seeds), enclosed in a tough, leathery shell, and borne ...

s that

mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

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 versus ''Eucalyptus'' forest, but the species were different. One way in which the avifauna (local assortment of bird species) 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, experience population declines when ''Eucalyptus'' groves replace oak forest. Birds that thrive in ''Eucalyptus'' groves in California tend to prefer tall vertical habitat. These avian species include herons and egrets, which also nest in redwoods. The

Point Reyes Bird Observatory Point Blue Conservation Science, founded as and formerly named the Point Reyes Bird Observatory (PRBO), is a California-based wildlife conservation and research non-profit organization. Overview Point Blue was founded in 1965 to study bird migra ...

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 pines.

Photo album

File:Eucalyptus macarthurii UC.jpg, Mature ''

Eucalyptus macarthurii ''Eucalyptus'' () is a genus of over seven hundred species of flowering trees, shrubs or mallees in the myrtle family, Myrtaceae. Along with several other genera in the tribe Eucalypteae, including '' Corymbia'', they are commonly known as euca ...

'', at the

University of Canterbury The University of Canterbury ( mi, Te Whare Wānanga o Waitaha; postnominal abbreviation ''Cantuar.'' or ''Cant.'' for ''Cantuariensis'', the Latin name for Canterbury) is a public research university based in Christchurch, New Zealand. It was ...

File:E.sideroxylon, branchlets, stems, leaves, capsules & buds.jpg, ''

Eucalyptus sideroxylon ''Eucalyptus sideroxylon'', commonly known as mugga ironbark, or red ironbark is a small to medium-sized tree that is endemic to eastern Australia. It has dark, deeply furrowed ironbark, lance-shaped adult leaves, flower buds in groups of se ...

'', showing fruit (capsules) and buds with operculum present. File:Bach dan.jpg, ''Eucalyptus'' forest in East Gippsland, Victoria. Mostly ''E. albens'' (white box). File:Applebox.JPG, '' E. bridgesiana'' (apple box) on Red Hill, Australian Capital Territory. File:euc.uk.600pix.jpg, '' E. gunnii'' planted in southern England. The lower part of the trunk is covered in ivy. File:Eucalyptus cinera x pulverulenta.jpg, ''

Eucalyptus cinerea ''Eucalyptus cinerea'', commonly known as the Argyle apple, mealy stringbark or silver dollar tree, is a species of small- to medium-sized tree that is endemic to south-eastern Australia. It has rough, fibrous bark on the trunk and branches, usu ...

'' x '' pulverulenta'' - National Botanical Gardens Canberra File:Eucalyptus gall.jpg, ''Eucalyptus'' gall File:CPonte Eucalyptus.jpg, '' E. grandis''. Province of Buenos Aires, Argentina. File:Eucalipto Galicia.JPG, ''Eucalyptus'' plantation near Viveiro, in

in Northwest Spain. Mostly ''E. globulus'' File:Snow Gum1.JPG, A snow gum (''E. pauciflora''), in winter in the Australian Alps File:Eucalyptus rubida.jpg, '' E. rubida'' (

candlebark gum ''Eucalyptus rubida'', commonly known as candlebark, ribbon gum or white gum, is a species of small to medium-sized tree that is endemic to south-eastern Australia. It has smooth bark, sometimes with rough bark at the base, lance-shaped or curved ...

) in Burra, New South Wales. File:Sydney Blue Gums Kippara Forest via Wauchope.JPG,

Sydney blue gum ''Eucalyptus saligna'', commonly known as the Sydney blue gum or blue gum, is a species of medium-sized to tall tree that is endemic to eastern Australia. It has rough, flaky bark near the base of the trunk, smooth bark above, lance-shaped to c ...

s west of Port Macquarie, New South Wales File:Eucalyptus Chapmaniana 5198.JPG, ''

Eucalyptus chapmaniana ''Eucalyptus chapmaniana'', commonly known as the Bogong gum, is a species of small to medium-sized tree endemic to montane and eastern Australia. It has rough, fibrous and fissured bark on most of the trunk and smooth light brown to grey bark o ...

'' (bogong gum) in Kew Gardens, London File:Sherbrooke forest Victoria 220rs.jpg, '' E. regnans'' trees in

Sherbrooke Forest Sherbrooke Forest is a wet sclerophyll forest within Dandenong Ranges National Park, 40 km east of Melbourne, in Victoria, Australia, close to the suburb of Belgrave. It lies within an altitude of 220–500 m asl and is dominated by the t ...

, Victoria File:Dean-Nicolle-Deanei.JPG, '' E. deanei'',

Blue Mountains National Park The Blue Mountains National Park is a protected national park that is located in the Blue Mountains region of New South Wales, in eastern Australia. The national park is situated approximately west of Sydney, and the park boundary is quite ...

File:Prospectcreek.jpg, Eucalypt woodland area near Prospect Creek in western

. Mostly '' E. amplifolia'' and '' E. tereticornis''.

References

General source

* * Blakely, W.F., ''A Key to the Eucalypts: with descriptions of 522 species and 150 varieties''. Third Edition, 1965, Forest and Timber Bureau, Canberra. * 5th edition. * Third edition. vol. 1. ''South-eastern Australia''. * Kelly, Stan, text by G. M. Chippendale and R. D. Johnston, ''Eucalypts: Volume I''. Nelson, Melbourne 1969, 1982, etc. * * *

External links

Lucid Online Player - EUCLID Eucalypts of Australia
(

Multi-access key In biology or medicine, a multi-access key is an identification key which overcomes the problem of the more traditional single-access key In phylogenetics, a single-access key (also called dichotomous key, sequential key, analytical key, or pathway ...

) to 917 species/subspecies taxonomy as of December 2009.
ANPSA Plant Guide: ''Eucalyptus'', ''Corymbia'' and ''Angophora''

Currency Creek Arboretum - Eucalypt Research

b

(2005-current)

* ttp://www.hort.purdue.edu/newcrop/duke_energy/Eucalyptus.html Handbook of Energy CropsDuke, James A. 1983.
''The Eucalyptus of California: Seeds of Good or Seeds of Evil?''
Santos, Robert. 1997 Denair, CA : Alley-Cass Publications
"The Rise and Fall of the Gum Tree: How California Came to Love—then Disown—Eucalyptus"
Farmer, Jared. 2014.
EUCALYPTOLOGICS: Information Resources on ''Eucalyptus'' cultivation around the World
Iglesias Trabado, Gustavo (2007-current) {{Authority control * Taxa described in 1789 Taxa named by Charles Louis L'Héritier de Brutelle Australasian realm flora