The
Tasmanian Blue Gum,
Southern Blue Gum or
Blue Gum, (
Eucalyptus globulus) is an
evergreenIn 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...
tree, one of the most widely cultivated trees native to
AustraliaAustralia , 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...
. They typically grow from 30 to 55 m (98 to 180 ft) tall. The tallest currently known specimen in Tasmania is 90.7 m tall. There are historical claims of even taller trees, the tallest being 101 m (330 ft). The natural distribution of the species includes
TasmaniaTasmania 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...
and southern
VictoriaVictoria is the second most populous state in Australia. Geographically the smallest mainland state, Victoria is bordered by New South Wales, South Australia, and Tasmania on Boundary Islet to the north, west and south respectively....
(particularly the Otway Ranges and
southern GippslandSouth Gippsland, a region of Gippsland in Victoria, Australia, is a well-watered region consisting of low, rolling hills descending to the coast in the south and the Latrobe Valley in the north. Low granite hills continue into Wilsons Promontory, the southernmost point of Victoria and mainland...
). There are also isolated occurrences on
King IslandKing Island is one of the islands that make up the state of Tasmania, Australia. It is located in the Roaring Forties of Bass Strait, off the north-western tip of the main island of Tasmania, about half way between Tasmania and the mainland state of Victoria. The southernmost point is called Stokes...
and
Flinders IslandFlinders Island may refer to:In Australia:* Flinders Island , in the Furneaux Group, is the largest and best known* Flinders Island * Flinders Island , in the Investigator Group* Flinders Island...
in Bass Strait and on the summit of the
You YangsThe You Yangs are a series of granite ridges that rise to 364m above the Werribee Plain approximately 55km south west of Melbourne and 22km north east of Geelong, in Victoria, Australia. The main ridge runs roughly N-S for about 9 km, with a lower extension running for about 15 km to the west...
near Geelong. There are naturalized non-native occurrences in southern
EuropeEurope 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...
(Galicia,
Akamas, CyprusAkamas , is a promontory and cape at the northwest extremity of Cyprus with an area of 230 square kilometres. Ptolemy described it as a thickly wooded headland, divided into two by summits [a mountain range] rising towards the north...
, and
PortugalPortugal , 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...
), southern
AfricaAfrica 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...
,
New ZealandNew Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
, western
United StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
(
CaliforniaCalifornia 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...
),
HawaiiHawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
and
MacaronesiaMacaronesia is a modern collective name for several groups of islands in the North Atlantic Ocean near Europe and North Africa belonging to three countries: Portugal, Spain, and Cape Verde...
.
The d'Entrecasteaux expedition made immediate use of the species when they discovered it, the timber was used to improve their oared boats. The Tasmanian Blue Gum was proclaimed as the
floral emblem of
TasmaniaTasmania 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...
on 27 November 1962. The species name is from the
LatinLatin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
globulus, a little button, referring to the shape of the operculum.
Description
The
barkBark 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...
sheds often, peeling in large strips. The broad juvenile
leavesA 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....
are borne in opposite pairs on square stems. They are about 6 to 15 cm long and covered with a blue-grey, waxy bloom, which is the origin of the common name "blue gum". The mature leaves are narrow, sickle-shaped and dark shining green. They are arranged alternately on rounded
stemsA stem is one of two main structural axes of a vascular plant. The stem is normally divided into nodes and internodes, the nodes hold buds which grow into one or more leaves, inflorescence , conifer cones, roots, other stems etc. The internodes distance one node from another...
and range from 15 to 35 cm in length. The buds are top-shaped, ribbed and warty and have a flattened
operculumAn 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:...
(cap on the flower bud) bearing a central knob. The cream-colored
flowerA 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...
s are borne singly in the leaf axils and produce copious nectar that yields a strongly flavored
honeyHoney 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...
. The
fruitIn broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...
s are woody and range from 1.5 to 2.5 cm in diameter. Numerous small
seedA seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
s are shed through valves (numbering between 3 and 6 per fruit) which open on the top of the fruit. It produces
rootIn vascular plants, the root is the organ of a plant that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial or aerating . Furthermore, a stem normally occurring below ground is not exceptional either...
s throughout the
soilSoil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...
profile, rooting several feet deep in some soils. They do not form
taprootA taproot is an enlarged, somewhat straight to tapering plant root that grows vertically downward. It forms a center from which other roots sprout laterally.Plants with taproots are difficult to transplant...
s.
The plant was first described by the French botanist
Jacques LabillardièreJacques-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...
in his publications
Relation du Voyage à la Recherche de la PérouseRelation du Voyage à la Recherche de la Pérouse is a book , issued in 1800, that gives an account of the 1791-1793 d'Entrecasteaux expedition to Australasia. The title refers to the search for La Pérouse, who disappeared in the region in 1788, a popular, though unsuccessful, object of the mission...
(1800) and
Novae Hollandiae Plantarum SpecimenNovae Hollandiae Plantarum Specimen is a two volume work describing the flora of Australia. The author was the French botanist Jacques Labillardière, who visited the region in 1792 with the d'Entrecasteaux expedition...
(1804). The author collected specimens at
Recherche BayRecherche Bay is located on the extreme south-eastern corner of Tasmania, Australia and was a landing place of the d’Entrecasteaux expedition to find missing explorer La Pérouse...
during the
d'EntrecasteauxAntoine Raymond Joseph de Bruni d'Entrecasteaux was a French navigator who explored the Australian coast in 1792 while seeking traces of the lost expedition of La Pérouse....
expedition in 1792.
Plantations
Blue gum is one of the most extensively planted eucalypts. Its rapid growth and adaptability to a range of conditions is responsible for its popularity. It is especially well-suited to countries with a Mediterranean-type climate, but also grows well in high altitudes in the tropics.
It comprises 65% of all
plantationA 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...
hardwoodHardwood is wood from angiosperm trees . It may also be used for those trees themselves: these are usually broad-leaved; in temperate and boreal latitudes they are mostly deciduous, but in tropics and subtropics mostly evergreen.Hardwood contrasts with softwood...
in Australia with approximately 4,500 km² planted. The tree is widely cultivated elsewhere in the world. It is primarily planted as a
pulpwoodPulpwood 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...
, and also as an important fuelwood in many countries.
Blue gums have historically been used as street trees but are now regarded as unsuitable by many municipalities due to their rapid growth and mature size.
Timber
Blue gum timber is yellow-brown, fairly heavy, with an interlocked grain, and is difficult to season. It has poor
lumberLumber or timber is wood in any of its stages from felling through readiness for use as structural material for construction, or wood pulp for paper production....
qualities due to growth stress problems, but can be used in
constructionIn the fields of architecture and civil engineering, construction is a process that consists of the building or assembling of infrastructure. Far from being a single activity, large scale construction is a feat of human multitasking...
, fence posts and poles.
Essential oil
The leaves are
steam distilledSteam distillation is a special type of distillation for temperature sensitive materials like natural aromatic compounds....
to extract
eucalyptus oilEucalyptus 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...
.
E.globulus is the primary source of global eucalyptus oil production, with
ChinaChinese 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...
being the largest commercial producer. The oil has therapeutic, perfumery, flavoring,
antimicrobialAn anti-microbial is a substance that kills or inhibits the growth of microorganisms such as bacteria, fungi, or protozoans. Antimicrobial drugs either kill microbes or prevent the growth of microbes...
and
biopesticideBiopesticides include "naturally occurring substances that control pests , microorganisms that control pests , and pesticidal substances produced by plants containing added genetic material or PIPs."Biopesticides are biochemical pesticides that are naturally occurring substances that control pests...
properties. Oil yield ranges from 1.0-2.4% (fresh weight), with cineole being the major isolate.
E.globulus oil has established itself internationally because it is virtually
phellandrenePhellandrene is the name for a pair of organic compounds that have a similar molecular structure and similar chemical properties. α-Phellandrene and β-phellandrene are cyclic monoterpenes and are double-bond isomers. In α-phellandrene, both double bonds are endocyclic and in β-phellandrene, one...
free, a necessary characteristic for internal pharmaceutical use. In 1870, Cloez, identified and ascribed the name "
eucalyptolEucalyptol 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,...
" — now more often called cineole — to the dominant portion of
E. globulus oil.
Environmental weed
It was introduced to
CaliforniaCalifornia 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...
in the mid-19th century, partly in response to the Southern Pacific Railroad's need for timber to make railroad ties, and is prominent in many parks in
San FranciscoSan Francisco , officially the City and County of San Francisco, is the financial, cultural, and transportation center of the San Francisco Bay Area, a region of 7.15 million people which includes San Jose and Oakland...
and throughout the state. Naturalists, ecologists, and the United States National Park Service consider it an
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....
due to its ability to quickly spread and displace native plant communities, while local authorities, especially many fire departments across California consider them to be a major fire hazard, although the
United States Department of AgricultureThe United States Department of Agriculture is the United States federal executive department responsible for developing and executing U.S. federal government policy on farming, agriculture, and food...
does not list it among its Invasive and Noxious plants list in California. Due to such reasons, programs across the state of California have been taken to remove all eucalyptus growth and restore native biomes in some park areas, such as on Angel Island in San Francisco Bay, and in the Hills of Oakland California, where Eucalyptus Trees helped fuel the 1991 Oakland Hills Firestorm.
Related species
Many botanists treat the Tasmanian Blue Gum as a
subspeciesSubspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
of a broader
speciesIn 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...
concept. This broader
E. globulus includes the following subspecies:
- E. globulus subsp. bicostata = E. bicostata
Eucalyptus bicostata, commonly known as Southern Blue Gum or Eurabbie, is a Eucalypt species native to Victoria and eastern New South Wales, Australia. It is called also Blue Gum and Victorian Blue Gum. It grows in wet forests on fertile soils in sheltered areas in ranges away from the coast.It is...
- Southern Blue Gum, Eurabbie, Victorian Blue Gum
- E. globulus subsp. globulus = E. globulus - Tasmanian Blue Gum
- E. globulus subsp. maidenii= E. maidenii
Eucalyptus maidenii, commonly known as Maiden's Gum, is a Eucalypt species native to eastern Victoria and southeastern New South Wales, Australia. It grows in wet forest on fertile soils in valleys in subcoastal ranges....
- Maiden's Gum
- E. globulus subsp. pseudoglobulus = E. pseudoglobulus
Eucalyptus pseudoglobulus, commonly known as Gippsland Blue Gum, is a Eucalypt species native to Victoria and the southeastern corner of New South Wales, Australia. It is called also Victorian Eurabbie, Bastard Eurabbie, and Blue Gum....
- Gippsland Blue Gum, Victorian Eurabbie
The broader
E. globulus concept is supported by
Royal Botanic Gardens, MelbourneThe Royal Botanic Gardens Melbourne are internationally renowned botanical gardens located near the centre of Melbourne, Victoria, Australia, on the south bank of the Yarra River. They are 38 hectares of landscaped gardens consisting of a mix of native and non-native vegetation including over...
and the Tasmanian Herbarium, but not by
Royal Botanic Gardens, SydneyThe Royal Botanic Gardens in Sydney, Australia, are the most central of the three major botanical gardens open to the public in Sydney....
where the four taxa are considered distinct
speciesIn 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...
.
External links