Common Name: Tasmanian Blue Gum

General Information

Eucalyptus globulus is a large evergreen tree with a narrow crown that becomes rounded for trees growing in the open; it usually grows up to 55 metres tall, exceptionally to 70 metres. The straight, cylindrical bole can be up to 200cm in diameter[].
This species is the most extensively planted eucalypt species in the world with a total of 800,000 hectares being grown in dozens of countries[]. It is cultivated in subtropical and at higher elevations in tropical regions for timber-work, as an ornamental tree and is the single most important species for the production of essential oil (eucalyptus oil)[, ]. This oil has a content of 60 - 80% cineole and is used in household utility products, perfumery, various medicinal applications and as a general flavouring.

Known Hazards

None known

Botanical References

, ,

Range

Australia - Tasmania, Victoria

Habitat

Damp marshy areas on moist loams and clays[]. Found in hilly country or moist valleys in deep rich soils[].

Properties

Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Evergreen Tree
Height	55.00 m
Growth Rate	Fast
Pollinators	Bees, Insects
Cultivation Status	Wild

Cultivation Details

Eucalyptus globulus is a plant mainly of the warm temperate zone and the subtropics, it is occasionally cultivated at elevations up to 3,100 metres in the tropics. It grows best in areas where annual daytime temperatures are within the range 18 - 23°c, but can tolerate 6 - 30°c[, ]. A moderately hardy species, though mature plants can be killed by temperatures of -8°c or lower, whilst young growth, even on old trees, will be severely damaged at 0°c[]. It prefers a mean annual rainfall in the range 700 - 1,400mm, but tolerates 550 - 1,800mm[].
Prefers a sunny position in a moderately fertile well-drained moisture retentive circum-neutral soil[]. Succeeds in most soils[], tolerating poor and dry soils, especially those low in mineral elements[]. Established plants are drought tolerant[]. Plants should not be grown in frost pockets or windy sites[]. Requires a sheltered position, disliking cold, dry or desiccating winds[]. Prefers a pH in the range 5.5 - 6.5, tolerating 5 - 7.5[].
Eucalyptus globulus does not tolerate shade, and is hence an obligate initial colonizer, which means that it does not spread easily into established forest. Thus, outside of its natural range, it is rarely found in self-maintaining, naturalized
populations without human intervention[].
The tree has a number of mechanisms for resisting fire. The shaggy bark is highly flammable and allows fire to spread quickly to the canopy, but the thick inner bark of mature trees prevents damage to the inner part of the tree in most cases. Post-fire regeneration is quick. Damaged bark is shed and buds resprout rapidly. In the case of top-kill, many new sprouts appear from the so-called lignotuber, a woody subterranean storage stem that resists fire and other damage to the above-ground stem. Fruits are resistant to fire, and high rates of seedbanking in the soil, as well as massive seed release from fire-damaged branches, lead to post-fire regeneration from seed. Hence Eucalyptus globulus spreads fire readily, causing grave potential danger to surrounding areas, but it recovers very well from fire itself[].
A very fast growing tree, new growth can be up to 2.5 metres per year in young plants, but slows down later[, , , ]. In a moist site in East Africa trees are recorded to obtain a height of 30 metres in 15 years, and 55 metres after 50 years. In drier regions, however, a maximum height of 30 metres is reached after 25 years[].
Trees can commence flowering and producing seed when 4 - 5 years old[].
The bluish juvenile leaves of this species are not willingly eaten by cattle, sheep or goats[]
Trees are very amenable to coppicing[]. Coppicing should be carried out at a height of 10 - 20cm above the ground; usually at least 3, and occasionally more coppice harvests are obtained[].
Plants are shallow-rooting and, especially in windy areas, should be planted out into their permanent positions when small to ensure that they do not suffer from wind-rock[]. They strongly resent root disturbance and should be container grown before planting out into their permanent position[].
Eucalyptus species have not adopted a deciduous habit and continue to grow until it is too cold for them to do so. This makes them more susceptible to damage from sudden cold snaps. If temperature fluctuations are more gradual, as in a woodland for example, the plants have the opportunity to stop growing and become dormant, thus making them more cold resistant. A deep mulch around the roots to prevent the soil from freezing also helps the trees to survive cold conditions[]. Many members of this genus are remarkably adaptable however, and there can be a dramatic increase in the hardiness of subsequent generations from the seed of survivors growing in temperate zones[].
Whilst most Eucalyptus species, grown in small numbers outside their native range, can be an attractive and useful addition to the landscape, certain species (including this one) are more problematic. When grown in monocultures, especially outside their native range, they can become an environmental disaster. They are voracious, especially in their use of water; they are allelopathic, inhibiting the growth of the native flora; they reduce habitats for native fauna; and encourage the worst possible attitudes to land use and conservation[].
The bruised leaves emit a powerful balsamic smell[].
This species is the national emblem of Tasmania[, ].

Edible Uses

An essential oil from the fresh or dried leaves is used as a flavouring in sweets, baked goods, ice cream etc[, ].

Medicinal

Eucalyptus leaves are a traditional Aboriginal herbal remedy. The essential oil found in the leaves is a powerful antiseptic and is used all over the world for relieving coughs and colds, sore throats and other infections[]. The essential oil is a common ingredient in many over-the-counter cold remedies[].
The adult leaves, without their petioles, are antiperiodic, antiseptic, aromatic, deodorant, expectorant, febrifuge, hypoglycaemic and stimulant[, , , ].

The leaves, and the essential oil they contain, are antiseptic, antispasmodic, astringent, expectorant, febrifuge, haemostatic, stimulant, tonic and vermifuge[, ]. Extracts of the leaves have antibacterial activity[]. The essential oil obtained from various species of eucalyptus is a very powerful antiseptic, especially when it is old, because ozone is formed in it on exposure to air. It has a decided disinfectant action, destroying the lower forms of life[]. The oil can be used externally, applied to cuts, skin infections etc, it can also be inhaled for treating blocked nasal passages, it can be gargled for sore throat and can also be taken internally for a wide range of complaints[]. Some caution is advised, however, because like all essential oils, it can have a deleterious effect on the body in larger doses[]. The oil from this species has a somewhat disagreeable odour and so it is no longer used so frequently for medicinal purposes, other members of the genus being used instead[].

An oleo-resin is exuded from the tree[]. It can also be obtained from the tree by making incisions in the trunk[, ]. This resin contains tannin and is powerfully astringent, it is used internally in the treatment of diarrhoea and bladder inflammation[, , ], externally it is applied to cuts etc[, ].

The essential oil is used in aromatherapy. Its keyword is 'Respiratory system'[].

Agroforestry Uses:

This species has a wide-spreading, dense root system and is commonly planted in S. Europe, especially in Italy, Spain and Portugal, for soil stabilization and forming windbreaks[, , , ]. Trees have also been planted in marshy areas, where they have the ability to reduce the wetness of the land (because they transpire so much water) thus getting rid of mosquitoes that were breeding there[, ].
Young plants make a useful living fence because they are unpalatable to livestock[].
The flowers are a source of nectar for bees, giving honey with a flavour like muscat grapes[, ].
Trees are gross feeders and can severely stunt the growth of nearby plants[].

Other Uses

The leaves and the essential oil in them are used as an insect repellent[, , , ]. A decoction of the leaves is used for repelling insects and vermin[]. Africans use finely powdered bark as an insecticidal dust[].

An essential oil is obtained from the leaves[, , ]. It has a content of 60 - 80% cineole and is used in perfumery and in medicines[, ]. Its special fragrance is used in perfumery for Eau-de-Cologne, air freshener, bath oils, and speciality perfumes[]. The antiseptic properties of the oil are utilized in disinfectants, household cleanings, tooth paste and sanitary products[]. The essential oil is also used in spot removers for cleaning off oil and grease[]. The yield is about 0.9% by steam distillation[]. Total yields of 40 - 45 kilos of oil per hectare have been reported[].

A yellow/brown dye is obtained from the young leaves. It does not require a mordant[].
Grey and green dyes are obtained from the young shoots[].
A dark green dye is obtained from the young bark[].

Kino (a red substance resembling resin) is obtained from the tree[]. Rich in tannins, it is readily soluble in water producing a pale reddish-yellow solution that is slightly acid[]. It can be used medicinally and for tanning.

The heartwood is pale grey to pink or reddish brown; it is fairly distinctly demarcated from the paler, up to 5cm wide band of sapwood. The grain is often interlocked, sometimes straight with patches of spiral grain; texture moderately
coarse. The wood often contains gum veins, brittle heart is common. The wood is hard and strong; moderately durable at best, being susceptible to insect, termite and marine borer attacks. Wood from plantations often has a lower density than that from natural stands. Shrinkage is extremely high; air-drying may pose problems, because twisting and collapse can be severe. Care must be taken in kiln drying to prevent tangential checking, and quarter-sawing is recommended before drying as well as initial air drying to 30% moisture content. The dried wood is not stable in service. It is rather difficult to work, due to its high density and the presence of interlocked grain; blunting of sawteeth and cutting edges is severe, nailing is best done after pre-boring; gluing properties are satisfactory. The wood bends well and accepts most finishes, and it sands to a smooth surface. It is used for poles, posts, construction, low grade veneer, plywood, flooring, furniture, tools, boxes, crates, pallets, railway sleepers, fibreboard and particleboard. It is also suitable for marine construction, ship and boat building, vehicle bodies, toys and novelties, turnery, interior trim, core stock, joinery and mine props[, ]. It is an important source of pulp for the production of printing, writing, specialty and tissue papers[, , ].
The wood is a very important fuel and is much used for charcoal making[]. It has an energy value of 18,000 - 19,400 kJ/kg and is recorded to burn free, leave little ash, and carbonize easily to good charcoal[].

Propagation

Seed - surface sow late winter/early spring in a sunny position in a greenhouse[, , ]. Species that come from high altitudes appreciate 6 - 8 weeks cold stratification at 2°c[]. Pot up the seedlings into individual pots as soon as the second set of seed leaves has developed, if left longer than this they might not move well. Plant out into their permanent positions in early summer and give them some protection from the cold in their first winter. The seed can also be sown in early summer, the young trees being planted in their final positions in late spring of the following year. The seed has a long viability[].