The Tasmanian Blue Gum, Southern Blue Gum or Blue Gum, (Eucalyptus globulus) is an evergreentree, one of the most widely cultivated trees native to Australia. 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 (297 ft). There are historical claims of even taller trees, the tallest being 101 m (330 ft). The natural distribution of the species includes Tasmania and southern Victoria (particularly the Otway Ranges and southern Gippsland). There are also isolated occurrences on King Island and Flinders Island in Bass Strait and on the summit of theYou Yangs near Geelong. There are naturalized non-native occurrences in southern Europe (Galicia,Akamas, Cyprus, and Portugal), southern Africa, New Zealand, western United States (California), Hawaiiand Macaronesia, Caucasus (Western Georgia).
Roger G. Skolmen and F. Thomas Ledig
Bluegum eucalyptus (Eucalyptus globulus), also called Tasmanian bluegum, is one of the world's best known eucalyptus trees. It is the "type" species for the genus in California, Spain, Portugal, Chile, and many other locations. One of the first tree species introduced to other countries from Australia, it is now the most extensively planted eucalyptus in the world.
Regularity: Regularly occurring
Native of Tasmania; widely cultivated in Sri Lanka and India
State - Kerala, District/s: Alappuzha, Idukki, Thrissur, Palakkad, Wayanad"
was introduced into California in 1856 and into Hawaii in about 1865.
It has naturalized in both states [3,7]. It is a fairly common
ornamental in Arizona but has not naturalized there . The planted
range in California extends from Humboldt County south to San Diego
County, with best growth in the coastal fog belt near San Francisco.
There are numerous plantings in the Central Valley from Redding south to
Bakersfield and San Bernardino. Hawaii has about 12,000 acres (5,000
ha) of planted and naturalized bluegum eucalyptus, almost all of them on
the islands of Hawaii and Maui .
Regional Distribution in the Western United States
This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):
3 Southern Pacific Border
Occurrence in North America
The species was introduced into California in 1856 (1) and into Hawaii about 1865 (18) and has become naturalized in both States. It is also fairly common as an ornamental in Arizona but is not naturalized there. In California, it is now primarily used in line plantings along roads and as windbreaks, but formerly, extensive plantations were established. Plantings total about 16 000 ha (40,000 acres) (17). The planted range in California extends from Humboldt County in the north to San Diego County in the south, with best growth in the coastal fog belt in the vicinity of San Francisco. Numerous plantings are seen in the Central Valley from Redding, south through Fresno to Bakersfield, and San Bernardino. Hawaii has about 5000 ha (12,000 acres)-almost all of them on the islands of Hawaii and Maui. In California and Hawaii the tree regenerates within and near the edges of plantations. In some areas of Hawaii it spreads fast enough to be considered a pest by ranchers.
Recently, the species has also been planted in its native Tasmania where it is an important pulpwood source (22).
Bluegum eucalyptus is an introduced, deciduous tree that generally grows
from 98 to 180 feet (30-55 m) tall [3,10]. Some bluegums have attained
heights of 260 feet (80 m) in California . Most height growth of
bluegum eucalyptus occurs within the first 5 to 10 years; 60 to 70
percent of total height growth is achieved by about age 10. Bluegum
eucalyptus typically grows in dense monocultures .
The sclerophyllous leaves are 4 to 11 inches (10-30 cm) long . The
flower clusters develop within an envelope formed by two bracteoles
which split and are shed, exposing the flower buds . The fruit is a
woody capsule 0.25 to 1 inch (6-25 mm) in diameter . The bark is
shreddy, peeling in large strips .
Bluegum eucalyptus generally does not form a taproot. It produces roots
throughout the soil profile, rooting several feet deep in some soils .
Key Plant Community Associations
Most dense bluegum eucalyptus stands in California and Hawaii are almost
devoid of understory vegetation, except for a few hardy grasses. In
Hawaii, firetree (Myrica faga) sometimes invades bluegum stands, and the
noxious passion fruit vine (Passiflora mollissima) has been found in
young bluegum eucalyptus coppice stands .
In its native habitat bluegum eucalyptus grows in pure stands and in
mixtures with many other eucalypt species. In California, it has been
planted with forest redgum eucalyptus and river redgum eucalyptus (E.
camaldulensis). In Hawaii, it has been planted with many other
This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):
More info for the term: shrub
FRES28 Western hardwoods
FRES34 Chaparral - mountain shrub
FRES42 Annual grasslands
by cool, wet winters and dry, warm summers . In coastal California,
it does well with only 21 inches (530 mm) of annual rainfall accompanied
by a pronounced dry season, primarily because frequent fogs compensate
for lack of rain .
Bluegum eucalyptus grows well on a wide range of soils, but requires
good drainage, low salinity, and a soil depth of 2 feet (0.6 m) or more.
In California, it grows best on deep alluvial soils because of the
greater moisture supply . Hawaiian soils supporting bluegum
eucalyptus are about 3 feet (0.9 m) deep. They are usually acidic,
moderately well-drained, silty clay loams [40,42].
In California, bluegum eucalyptus occurs at elevations below 1,000 feet
(300 m) . It occurs at 1,400 to 6,000 feet (425-1,800 m) in Hawaii
Habitat: Cover Types
This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):
248 Knobcone pine
250 Blue oak - Digger pine
255 California coast live oak
Habitat: Plant Associations
This species is known to occur in association with the following plant community types (as classified by Küchler 1964):
K030 California oakwoods
K048 California steppe
Soils and Topography
In Hawaii, the tree grows very well on Typic and Hydric Dystrandepts, soils of the latosolic brown forest great soil group. These soils are generally 0.9 in (3 ft) deep, acid in reaction, and formed on volcanic ash. In California, the tree grows well on a much wider range of soils than in Hawaii, from the Ultisols and Alfisols developed on deeply weathered sedimentary deposits and sandstone to Inceptisols and Aridisols developed on a wide variety of parent materials.
In Portugal, almost 15 percent of the land area is planted to this species. Most stands are on soils developed from sandstone and limestone, which have been badly degraded by cultivation since ancient times. Best yields occur on the heavy texture clay-loams and clays (11).
Foodplant / parasite
Golovinomyces orontii parasitises live Eucalyptus globulus
Foodplant / gall
larva of Ophelimus cf. maskelli causes gall of live leaf of Eucalyptus globulus
Associated Forest Cover
Most of the dense bluegum eucalyptus stands in California and Hawaii are noted for being almost devoid of understory vegetation, except for a few hardy grasses. Although this condition is most likely related to the rather dry climate that provides the best site for the species, it has also been shown that the leaves of the tree produce water soluble phytotoxins that can prevent radicle growth of many herbaceous plants (7). In Hawaii, firetree (Myrica faya) is a species that sometimes invades bluegum eucalyptus stands. The noxious passion fruit vine (Passiflora mollissima) has also been found thriving in a young coppice stand.
Diseases and Parasites
In California, bluegum eucalyptus stands are highly susceptible to fire during the dry season. The bark, which hangs in strips from the stems, readily carries fire into the crowns, and the leaves contain volatile oils that produce a hot fire. Trees are rarely killed by fire, however, as they sprout vigorously from the stems and bases (8). In the moister climate of Hawaii, fire has not been a problem in bluegum eucalyptus stands.
Seedlings are intolerant of frost and temperatures of -5° to -10° C (23° to 14° F) usually kill them. Frost resistance increases with maturity, juvenile foliage being less resistant than mature foliage (4). In 1972 a severe frost in the hills of Berkeley, CA, completely defoliated most of the mature bluegum eucalyptus. The trees were considered dead by several authorities and a salvage logging program was started to remove the fire hazard. A few months later, most of the "dead" trees sprouted from the stems and bases and began to grow again. This sprouting was judged undesirable and several experiments were undertaken aimed at preventing it. The most successful treatment found was to flood axe frills made at the tree bases with a 0.36 kg/1 (3 lb/gal) solution of glyphosphate in water (10). This permanently killed the trees.
The tree is susceptible to drought, particularly on shallow soils. On such soils, subsoiling has been used effectively to permit deeper rooting and to overcome drought susceptibility.
Several insects attack bluegum eucalyptus, although none has been a serious problem in California or Hawaii. One that is common in many parts of the world is the wood borer, Phoracantha semipunctata, which has caused severe damage in South Africa and Western Australia. A scale insect, Eriococcus coriaceus, has caused high mortality in New Zealand. Several defoliating insects in the genera Gonipterus, Chrysophtharta, and Mnesampela, attack the species.
Fungi have generally not been a severe problem with bluegum eucalyptus. Damping off in nurseries caused by Botrytis cinerea has been a problem but is easily controlled. Pythium and Rhizoctonia spp. have also caused damping-off in containers and flats, particularly when old seed was used (16). Fusarium spp. have destroyed quantities of stored seed in Spain. Attack by Diplodia and Armillaria has been reported from several countries, but neither disease is considered serious (8,23).
Fire Management Considerations
Fuel buildup occurs very rapidly in unmanaged bluegum eucalyptus stands
in California [1,33]. Fuel reduction programs can reduce wildfire
hazard, as can the establishment of fuelbreaks [1,31].
In December, 1972, the San Francisco Bay Area experienced a severe cold
snap, resulting in extensive frost damage to bluegum eucalyptus trees
[6,18]. Frost-killed leaves and twigs increased bluegum eucalyptus
litter ten-fold. By early 1973, following a particularly hot, dry
summer and autumn, the litter combined with standing dead and damaged
bluegums constituted a major fire hazard [1,6,18]. Several fuel
reduction methods were proposed: mechanical removal of trees, thinning
of present stands, and prescribed fire. The first two alternatives are
commonly applied now in freeze-killed or damaged stands. Broadcast
fires have been used with success in undisturbed areas under reasonably
moist (13-19% fuel moisture) weather conditions. Spring fires have
reduced fuel loads up to 87 to 96 percent without damage to overstory
trees. Prescribed burning has been widely applied to eucalyptus forests
in Australia to reduce fuel loads and prevent wildfires .
Plant Response to Fire
Bluegum eucalyptus recovers well from fire . Epicormic sprouting is
common in trees only scorched by fire. It is also common in trees where
crown fire occurred but bark was thick enough to protect dormant branch
buds. Heat-damaged bark is shed, and sprouting proceeds rapidly .
Top-killed trees sprout from the lignotuber. Vigorous sprouting is
supported by food reserves stored in the root system and lignotuber .
Bluegum eucalyptus also establishes from seed after fire. Some seed is
already stored in the seedbank. Release of crown-stored seed is
triggered by shoot death, and crown-stored seeds are rapidly
disseminated after fire .
In 1929, a catastrophic fire burned a bluegum eucalyptus stand in
California. The forest regenerated to a fully stocked condition. In
November 1946, a second fire burned much of the same area. Again, the
forest regenerated. By 1983, it was a very dense uneven-aged stand .
Immediate Effect of Fire
Crown fire's effect upon bluegum eucalyptus varies. Because the stringy
outer bark is highly flammable and bark thickness is readily reduced by
fire, past fire frequency largely determines the relative protection
bark offers. Repeated fire damage to bark before bark thickness has
been restored may result in top-kill, or at times, tree mortality. If
bark is sufficiently thick, bluegum eucalyptus branches survive crown
fire and send out epicormic sprouts . No studies quantifying bark
thickness with tree survival were found.
Tree with adventitious-bud root crown/soboliferous species root sucker
Ground residual colonizer (on-site, initial community)
Crown residual colonizer (on-site, initial community)
Initial-offsite colonizer (off-site, initial community)
Secondary colonizer - off-site seed
Most eucalyptus communities in Australia have evolved in the presence of
periodic fire . Bluegum eucalyptus is highly flammable, but is
seldom killed by fire. The bark catches fire readily, and deciduous
bark streamers and lichen epiphytes tend to carry fire into the canopy
and to disseminate fire ahead of the main front [3,7,8,50]. Other
features of bluegum eucalyptus that promote fire spread include heavy
litter fall, flammable oils in the foliage, and open crowns bearing
pendulous branches, which encourages maximum updraft [3,9]. Despite the
presence of volatile oils that produce a hot fire, leaves of bluegum
eucalyptus are classed as intermediate in their resistance to
combustion, and juvenile leaves are highly resistant to flaming .
Adaptations to fire include seedbanking, sprouting, and heat-resistant
seed capsules [3,7]. Seed capsules protect the seed for a critical
short period as the fire reaches the crowns; this protection delays
penetration of heat to the seeds. Seeds were protected for about 4
minutes from a lethal rise in temperature when capsules were subjected
to a heat of 826 degrees Fahrenheit (440 deg C) . Following all
types of fire, an accelerated seed shed occurs, even where crowns are
only subjected to heat scorch.
Seed production and dissemination: Flowers are pollinated by insects
and hummingbirds . Seed set begins at approximately 4 to 5 years of
age. Good seed crops are produced in most locations at 3- to 5-year
intervals . The seeds of are relatively small and abundant .
Capsules open immediately on ripening, and the seed is dispersed by wind
within 1 to 2 months [7,24]. Dispersal distance from one 131-foot (40
m) tree, with winds of 6 mph (10 km/h), was 66 feet (20 m) . Newly
released seeds germinate within a few weeks under suitable conditions.
Germination is epigeal. Seed collections from individual trees in
California had highly variable germination rates, ranging from 2 to 80
percent within a 30-day germination period . Soil-stored seed under
older stands often germinates prolifically following logging or other
Vegetative reproduction: Bluegum eucalyptus sprouts readily from the
bole, from stumps of all sizes and ages, from the lignotuber, and from
the roots [7,17]. The lignotuber can live for many years in the soil
after stems die back . Bluegum eucalyptus also reproduces by
Growth Form (according to Raunkiær Life-form classification)
Obligate Initial Community Species
In Hawaii and California, bluegum eucalyptus regenerates within and near
the edges of plantations. It does not spread far and rarely invades
wildlands [2,7]. It has, however, invaded an oak woodland on Angel
Island in the San Francisco Bay .
Bluegum eucalyptus is shade intolerant; failure to regenerate within
forests in the absence of fire is related to low light intensities .
Bluegum eucalyptus is drought tolerant and somewhat frost hardy. Frost
resistance increases with maturity .
Reaction to Competition
Although leaves of the species produce water-soluble toxins that may help prevent competition by larger trees (7), one or two maintenance cleanings are usually required shortly after planting to free seedlings from being overtopped by grasses. In Hawaii, sprouts from buried lignotubers often grow as much as 30 cm (12 in) horizontally through litter and grass before emerging to light.
Life History and Behavior
In California, flowering occurs from November to April. Fruit ripens
from October to March, about 11 months after flowering. In Hawaii, some
trees flower throughout the year, but flowering is heaviest in February
and March. Fruit ripens throughout the year .
Elsewhere than Hawaii, where foresters have had no experience beyond one rotation, bluegum eucalyptus is normally carried for three coppice rotation after the first, or seedling rotation. Rotations rang from 5 to 10 years in different countries and sites Undesirable shoots are usually removed during the first 2 years of a coppice crop, but thinning is normally not done. In Portugal, coppice stands are some times managed by the system of "coppice with standards" so that a sawtimber crop of the straightest an best trees is retained between coppice harvests to b cut as sawtimber when of suitable size (8).
In Portugal, coppice rotations are 10 to 15 year with annual yields normally 15 to 20 m/ha (214 t 286 W/acre) (11).
Nursery-grown seedlings in containers reach plantable size, about 30 to 40 cm (12 to 16 in) high in 3 to 4 months. Seedlings can be established in planted with bare roots, but success is highly de pendent on favorable wet weather after planting Seedlings are, therefore, usually grown in container and planted with a root ball. Seedlings are not frost resistant (23).
With favorable weather conditions on good sites in Hawaii, seedlings that germinate after logging am are not suppressed can be expected to be 1 in (3 ft tall at 6 months, 2 m (6 ft) at 1 year, and 4 m (13 ft at 2 years. Seedlings in four coppice stands in Hawaii grew poorly because they were generally suppressed by coppice shoots from stumps (21). Despite this, an average annual growth of 1.1 cm (0.4 in) in diameter at stump height and 1.4 m (4.6 ft) in height was recorded for all seedlings in stands 3, 4, 5, and 6 years old. Stocking of seedlings and coppice shoots in these stands was high, averaging more than 6,000 stems per hectare (2,400/acre). Measurements in six representative planted stands in California that were 5 years or less in age gave an average annual height growth of 2 m (6.7 ft) (19). In Victoria, Australia, unfertilized planted seedlings grew I m (3 ft) annually during a 4-year period, while fertilization of seedlings at three different levels nearly doubled the growth rate (6). Bluegum eucalyptus seedlings show a strong response to nitrogen and phosphorus fertilization on many soils (23).
Seed Production and Dissemination
Flowering and Fruiting
Growth and Yield
These data are well within the range of those reported for other countries (8). Annual growth in northwestern Spain averages 20 m³ /ha (286 ft³/acre), but in southwestern Spain only 5 to 6 m³/ha (71 to 86 ft³ /acre). In Uruguay, 25 m³/ha (375 ft³ /acre) of annual growth is considered good. In Ethiopia and Portugal, at age 10 on the highest quality site, very good growth is 20 m³/ha (286 Wft³/acre) per year.
In California, 67 different stands were measured in 1924 (19). The mean annual growth of all these stands ranging from 2 to 42 years in age, was 19 m³/ha (271 ft³/acre). Ten of these stands, ranging from 13 to 16 years in age and similar to the plantation in Australia, averaged 19.6 cm (7.7 in) in d.b.h., and 20.4 m (67 ft) in height, and had a mean annual growth of 21 m³/ha (300 ft³ /acre). The tallest stand averaged 38.7 m (127 ft) at 23 years. The tallest stand in California is one planted in 1877 on the University of California campus at Berkeley; it contains trees that have been more than 61 rn (200 ft) tall since 1956 (1).
In Hawaii, 20 stands ranging in age from 2.5 to 35 years were evaluated in 1911 (18). Four of the stands were in the age range 11 to 20, somewhat similar to the plantations in Australia. In these four, the average d.b.h. was 29.2 cm (11.5 in), and average height was 23 m (76 ft). The tallest stand averaged 30.5 m (100 ft) at 14 years. Seven stands ranging in age from 5 to 20 years had an average annual yield of 20 m³/ha (286 ft³/acre). The tallest bluegurn eucalyptus trees in Hawaii were at Kukaiau Ranch, on the Island of Hawaii, and were about 61 m (200 ft) tall until logged at age 70.
Molecular Biology and Genetics
Hybrids Natural or controlled hybrids of bluegum eucalyptus with E. blakelyi, E. botryoides, E. cinerea, E. cypellocarpa, E. ovata, E. rudis, E. tereticornis, E. urnigera, and E. viminalis are known (8,14,18).
Barcode data: Eucalyptus globulus
Statistics of barcoding coverage: Eucalyptus globulus
Public Records: 2
Specimens with Barcodes: 5
Species With Barcodes: 1
National NatureServe Conservation Status
Rounded National Status Rank: NNA - Not Applicable
NatureServe Conservation Status
Rounded Global Status Rank: GNR - Not Yet Ranked
Bluegum eucalyptus is highly flammable and should not be planted near
homes and other structures . For information regarding the
eradication of bluegum eucalyptus, see Fiedler , Groenendaal ,
and Rice .
The leaves of bluegum eucalyptus release a number of terpenes and
phenolic acids. These chemicals may be responsible for the paucity of
accompanying vegetation in plantations . Natural fog drip from
bluegum eucalyptus inhibits the growth of annual grass seedlings in
bioassays, suggesting that such inhibition occurs naturally [10,34]. At
least one leaf extract has been shown to strongly inhibit root growth of
seedlings of other species . The frass from the chrysomelid beetle,
which feeds upon bluegum eucalyptus, is allelopathic to grasses at very
low levels .
Bluegum eucalyptus is used short-rotation fuel biomass plantations
[26,30,35]. The coppice method of regeneration is most common because
it allows, at least for a limited number of years, repeated harvesting
at short intervals and exploitation of exceptionally high early growth
In Hawaii, four 64-year-old coppice stands were studied 2 to 5 years
after logging. Seventy to eighty percent of the stumps had sprouted.
All stands also had seedlings. The seedlings made up more than 20
percent of the total number of stems, but contributed very little to
volume as they were usually suppressed by the sprouting stems .
Relevance to Humans and Ecosystems
Part unspecified: Yields eucalyptus oil used for nasal and pulmonary conditions in French Guiana.
Other uses and values
California . It is also a source of nectar for honey production
Bluegum eucalyptus oil has numerous medical applications. In
pharmaceutical preparations it has diaphoretic, expectorant,
insecticidal, and oestrogenic properties. The oil has antifungal and
antibacterial activity against Bacillus subtilis, Staphylococcus aureus,
and Escherichia coli. Eucalyptus oil is generally nonirritating,
nonsensitizing, and nonphototoxic to the skin. When taken internally,
it may be toxic to the kidneys and can be a nervous system depressant
The oil is used as a flavoring agent in cold and cough medicines. It is
used in disinfectants, antiseptic liniments, ointments, toothpastes, and
mouthwashes. It is used by veterinarians for treating influenza in
horses, distemper in dogs, and septicaemia in all animals.
Bluegum eucalyptus oil is used as a flavor ingredient in boiled sweets
and food products such as beverages, dairy desserts, candy, baked goods,
gelatins, puddings, and meat products . The cosmetic industry uses
it as a fragrance component in soaps, detergents, air fresheners, bath
oils, and perfumes .
Wood Products Value
It burns freely, leaves little ash, and produces good charcoal [7,33].
Plantations can be harvested for firewood every 7 years . It is
also widely used as pulpwood . The wood is unsuitable for lumber
because of excessive cracking, shrinkage, and collapse on drying ,
but is used for fenceposts, poles, and crates .
Value for rehabilitation of disturbed sites
sound barriers along highways [7,24,30]. After it becomes established,
however, it may suppress or eliminate other species .
The species is a major source of fuelwood in many countries of the world primarily because of its ability to coppice after cutting. The wood burns freely, leaves little ash, and produces good charcoal (8). The tree shows promise for use as industrial fuelwood in place of oil. Closely spaced and fertilized plantings in Victoria, Australia, produced mean annual increments of 9 to 14 metric tons per hectare (4 to 6 tons/acre) dry weight of stem wood during a 4-year period (3). In Hawaii, untended 3- to 6-year-old coppice stands average stem wood dry weights of 5 to 7 t/ha (2 to 3 tons/acre) per year. One stand, during its fifth year of growth, produced 14 t/ha (6 tons/acre). Another, during its second year, produced 8 t/ha (3.6 ton/acre) (20).
Bluegurn eucalyptus is much used for pulpwood, particularly so because its bark, acceptable in most pulping processes, adds greatly to the yield. It is used mostly for bleached products made by sulfate, sulfite, or bisulfite processes (8).
Other uses include the extraction of essential oils from the leaves, honey production from the flowers (that are also good pollen sources), plantings for erosion control, and roadside plantings to provide a noise and headlight buffer (8).
Because the wood is heavy and shrinks greatly in drying, it is unsuitable for lumber. Sawing of logs is difficult and the quality of lumber is poor because of growth stress problems. Main uses of bluegurn eucalyptus are for mining timber, fence posts, and poles (23). In South America, the straight, uniform poles are used extensively in construction (17). Lumber and veneer are produced on a fairly large scale in Portugal and Spain where the wood is used for cooperage, furniture, and flooring (8). A small amount of lumber used to be produced in Hawaii.
The Tasmanian blue gum, southern blue gum or blue gum, (Eucalyptus globulus) is an evergreen tree, one of the most widely cultivated trees native to Australia. They typically grow from 30–55 m (98–180 ft) tall. The tallest currently known specimen in Tasmania is 90.7 m (298 ft) tall. There are historical claims of even taller trees, the tallest being 101 m (331 ft). The natural distribution of the species includes Tasmania and southern Victoria (particularly the Otway Ranges and southern Gippsland). There are also isolated occurrences on King Island and Flinders Island in Bass Strait and on the summit of the You Yangs near Geelong. There are naturalised non-native occurrences in Spain and Portugal, Akamas, and other parts of southern Europe, southern Africa, New Zealand, western United States (California), Hawaii and Macaronesia, Caucasus (Western Georgia).
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 Tasmania on 27 November 1962. The species name is from the Latin globulus, a little button, referring to the shape of the operculum.
The bark sheds often, peeling in large strips. The broad juvenile leaves 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 stems and range from 15–35 cm (5.9–13.8 in) in length. The buds are top-shaped, ribbed and warty and have a flattened operculum (cap on the flower bud) bearing a central knob. The cream-coloured flowers are borne singly in the leaf axils and produce copious nectar that yields a strongly flavoured honey. The fruits are woody and range from 1.5–2.5 cm (0.59–0.98 in) in diameter. Numerous small seeds are shed through valves (numbering between 3 and 6 per fruit) which open on the top of the fruit. It produces roots throughout the soil profile, rooting several feet deep in some soils.
The plant was first described by the French botanist Jacques Labillardière in his publications Relation du Voyage à la Recherche de la Pérouse (1800) and Novae Hollandiae Plantarum Specimen (1804). The author collected specimens at Recherche Bay during the d'Entrecasteaux expedition in 1792.
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 plantation hardwood in Australia with approximately 4,500 km2 (1,100,000 acres) planted. The tree is widely cultivated elsewhere in the world. It is primarily planted as a pulpwood, 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.
In California, thousands of E. globulus were planted from the late 1800s onward, notably by the ranch owners as windrows to protect citrus groves from the harsh Santa Ana winds, particularly in Orange County. With the decline and eventual disappearance of the citrus business and rapid suburbanisation of the area, the surviving E. globulus became increasingly seen as an important part of the suburban landscape and are currently protected by various city ordinances.
Blue gum timber is yellow-brown, fairly heavy, with an interlocked grain, and is difficult to season. It has poor lumber qualities due to growth stress problems, but can be used in construction, fence posts and poles.
The leaves are steam distilled to extract eucalyptus oil. E. globulus is the primary source of global eucalyptus oil production, with China being the largest commercial producer. The oil has therapeutic, perfumery, flavoring, antimicrobial and biopesticide 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 phellandrene free, a necessary characteristic for internal pharmaceutical use. In 1870, Cloez, identified and ascribed the name "eucalyptol" — now more often called cineole — to the dominant portion of E. globulus oil.
E. globulus bark contains quinic, dihydroxyphenylacetic and caffeic acids, bis(hexahydroxydiphenoyl (HHDP))-glucose, galloyl-bis(HHDP)-glucose, galloyl-HHDP-glucose, isorhamentin-hexoside, quercetin-hexoside, methylellagic acid (EA)-pentose conjugate, myricetin-rhamnoside, isorhamnetin-rhamnoside, mearnsetin, phloridzin, mearnsetin-hexoside, luteolin and a proanthocyanidin B-type dimer, digalloylglucose and catechin. The hydrolyzable tannins tellimagrandin I, eucalbanin C, 2-O-digalloyl-1,3,4-tri-O-galloyl-β-D-glucose, 6-O-digalloyl-1,2,3-tri-O-galloyl-β-D-glucose, as well as gallic acid and (+)-catechin can also be isolated. Tricetin is a rare flavone aglycone found in the pollen of members of the Myrtaceae, subfamily Leptospermoideae, such as E. globulus.
It was introduced to California 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 Francisco and throughout the state. Naturalists, ecologists, and the United States National Park Service consider it an invasive species 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 Agriculture 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.
- E. globulus subsp. bicostata = E. bicostata - Southern Blue Gum, Eurabbie, Victorian Blue Gum
- E. globulus subsp. globulus = E. globulus - Tasmanian Blue Gum
- E. globulus subsp. maidenii= E. maidenii - Maiden's Gum
- E. globulus subsp. pseudoglobulus = E. pseudoglobulus - Gippsland Blue Gum, Victorian Eurabbie
The broader E. globulus concept is supported by Royal Botanic Gardens, Melbourne and the Tasmanian Herbarium, but not by Royal Botanic Gardens, Sydney where the four taxa are considered distinct species.
- Giant Trees Consultative Committee
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French Guiana: eucalyptus.
Names and Taxonomy
Eucalyptus globulus Labill. . There are four recognized subspecies
and one variety that occur in California [7,22,47,49]:
E. globulus ssp. bicostata Maiden
E. globulus ssp. globulus
E. globulus ssp. maidenii F. Muell
E. globulus ssp. pseudoglobulus Naudin ex Maiden
E. globulus var. compacta Labill. (dwarf bluegum)
Natural or controlled hybrids of bluegum eucalyptus are known with E.
blakelyi, E. botryoides, E. cinera, E. cypellocarpa, E. ovata, E. rudis,
E. tereticornis (forest redgum eucalyptus), E. urnigera, and E.
viminalis (manna eucalyptus) .
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