Common Name: Sidney Blue Gum

General Information

Eucalyptus saligna is a tall, evergreen tree with an open, irregular, spreading crown[]. It generally grows 30 - 50 metres tall, with a diameter at breast height of up to 200cm, although exceptional specimens can grow 65 metres tall and attain a diameter of 250cm[]. The bole is generally of excellent form, straight and clear of branches for half to two thirds of the total tree height[].
An important general-purpose hardwood in Australia, the tree is harvested from the wild for its timber, tannins and essential oil.
The tree has escaped from cultivation in some of the areas in which it is grown, and it is considered to be invasive in Hawaii and New Zealand[].

Known Hazards

None known

Botanical References

,

Range

Australia - New South Wales, Queensland.

Habitat

Mainly a tree of fertile valleys and slopes[]. Wet forest on soils of moderate fertility, often on slopes; at elevations up to 300 metres in the south of its range, to 1,000 metres in the north[, ].

Properties

Weed Potential	Yes
Medicinal Rating
Other Uses Rating
Habit	Evergreen Tree
Height	40.00 m
Growth Rate	Fast
Pollinators	Bees, Insects
Cultivation Status	Cultivated, Ornamental, Wild

Cultivation Details

The preferred climate is warm temperate to subtropical with a mild dry season of not more than 4 months, although Eucalyptus saligna has also proved to be highly suited for short-rotation plantations in tropical montane regions[]. In its native range it is found at elevations from sea level to 1,220 metres, whilst in the tropics trees have succeeded at elevations up to 1,980 metres[]. Trees at the higher elevations in its native range have experienced temperatures as low as -15°c and up to 15 frosts a year[, ]. Mean annual rainfall in its native range varies from 800 - 1,270 mm, though in the tropics it has succeeded with up to 7,620mm of rain[, ]. Although it can tolerate short dry periods, best growth is achieved on sites with a high rainfall well distributed throughout the year[]. The tree achieves its best growth on sites with about 2,540 mm annual rainfall, rather than on wetter sites, possibly because sunlight is greatly reduced by the cloud cover on wetter sites[].
Requires a position in full sun[]. Prefers a moist but well drained soil[]. Best development occurs on good quality, alluvial sandy loams, the tree also succeeding on podsols and volcanic loams[].
The plant develops a lignotuber - this is a woody tuber that starts to develop near the base of seedlings and can become massive in the mature plants of some species. It possesses embedded vegetative buds, allowing the plant to regenerate following crown destruction, for example by fire[].
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[].
Seed production commences when the tree is about 7 - 8 years old[].
Coppices, with rotations of 6 - 10 years are used for producing fuel wood and pulpwood[].
Annual wood production potential is 15 - 35 cubic metres per hectare[].
This fast-growing, light-demanding tree is highly sensitive to competition from weeds during the first 2 years, and therefore measures to control emerging weed growth must be carried out several times. The rapid early growth soon allows the tree to dominate competing vegetation[].
The glabrous leaves are aromatic when crushed[].
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[].

Edible Uses

None known

Medicinal

Kino resin, obtained from the trunk, is very astringent[]. Diluted, it can be taken internally as an effective treatment for dysentery, working because it is not absorbed at all from the stomach and only very slowly from the intestine, and is thus able to directly treat the lower part of the intestine. It can be used as a gargle and mouthwash to treat relaxed throat, loose teeth[, ].
Applied externally as a wash, it is an effective styptic and can used to treat cuts and skin problems[].

Agroforestry Uses:

The tree is used in reforestation[].
The flowers are a good source of nectar for bees[].

Other Uses

The bark contains 5.9 - 8.4% tannin[].

The essential oil yield from the leaves is 0.3-0.5%[]. The major compound found in the oil is alpha-pinene (71-84%)[]. The oil has insecticidal properties against bedbugs, black beetles, flies, lice, and mosquitoes[].

Kino (a red substance resembling resin) is obtained from the tree[]. Rich in tannins, kino resins are readily soluble in water producing a perfectly clear liquid of an orange-brown colour[]. They can be used medicinally; in tanning; as well as for preserving and dyeing natural fibres. When boiled in an iron pot they produce a thick, dark liquid that can be used as an ink[].
The resin oozes naturally from wounds in the trunk and can be tapped by making incisions in the bark. At first it is a thick liquid, but soon hardens upon exposure to the air and sun, typically drying to an amber-like material that consists of dark red angular fragments, rarely larger than a pea. Freshly exuded kino is more effective than kino that has been on the tree for a long while, since the soluble portion can be more or less washed out and the action of the sun can alter their chemical composition[].

The heartwood is red or pink. The wood is hard, stiff, coarse textured, usually straight grained, moderately durable, is easy to work and polishes well[]. It does not catch fire easily[]. It is an important general-purpose hardwood in Australia, and is favoured for railway sleepers, construction, flooring, cladding and panelling[, ].
Young, fast-grown trees are used for semi-chemical pulp. However, when the tree is grown slowly, the heartwood may become difficult to process[].

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[].