Classification of the genus Acacia (in the wider sense) has been subject to considerable debate. It is generally agreed that there are valid reasons for breaking it up into several distinct genera, but there has been disagreement over the way this should be done. As of 2017, it is widely (but not completely) accepted that the section that includes the majority of the Australian species (including this one) should retain the name Acacia, whilst other sections of the genus should be transferred to the genera Acaciella, Mariosousa, Senegalia and Vachellia[].

Common Name: Mimosa

General Information

Acacia dealbata is an evergreen large shrub or medium-sized tree with a conical or rounded crown; it usually grows from 6 - 15 metres tall, occasionaly reaching 30 metres. The bole is straight and cylindrical. The plant often suckers freely, especially if the main stem is cut down[, , ]. Unlike most Australian Acacias, this species retains its true leaves as it grows larger.
The tree has a wide range of traditional uses, as a food and source of materials. It can be used as a pioneer to restore native woodland, is used in soil stabilization projects, is coppiced for fuel and used in shelterbelt plantings. It is also often grown as an ornamental, and is cultivated commercially for its flowers and the essential oil they contain.
Acacia dealbata, as a legume with an ability to seed prolifically and to produce root suckers, is often among the first to colonize cleared land, which has led to it becoming a weed in many countries. It is a declared weed (category 1) in the Western Cape and a declared invader (category 2) across the rest of South Africa. It has various ecological and environmental impacts including the displacement of native vegetation, disruption to water flow leading to streambank erosion and changed nutrient cycling patterns. As a species that has already been widely introduced and in present in a large numbers of countries, it is likely that further accounts of its invasiveness may be reported[].

Known Hazards

Especially in times of drought, many Acacia species can concentrate high levels of the toxin Hydrogen cyanide in their foliage, making them dangerous for herbivores to eat.

Botanical References

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Range

Australia - Victoria, New South Wales, Tasmania

Habitat

Grows mostly in open or tall open forest or woodland, at high elevations on plateaux and in deep mountain valleys and gullies, often in low vegetation in subalpine areas, on swamp margins and stream banks[, ]. Dry forests[].

Properties

Weed Potential	Yes
Edibility Rating
Other Uses Rating
Habit	Evergreen Tree
Height	25.00 m
Growth Rate	Fast
Cultivation Status	Cultivated, Ornamental, Wild

Cultivation Details

A plant of the warm temperate and subtropical zones, where it can be found at elevations up to 1,500 metres. It grows best in areas where annual daytime temperatures are within the range 15 - 26°c, but can tolerate 6 - 32°c[]. When dormant, the plant can survive temperatures down to about -10°c, but young growth can be severely damaged at -1°c[]. If the plant is cut down by frosts, it with often resprout from the base to form a thicket of slender stems[]. It prefers a mean annual rainfall in the range 600 - 1,000mm, but tolerates 300 - 1,500mm[]. Plants require hot, sunny summers if they are to ripen their wood fully and flower freely.
Prefers a sandy loam and a very sunny position sheltered from strong winds[, ]. Succeeds in any good garden soil that is lime-free and well-drained[, ]. Prefers a pH in the range 5.5 - 6.5, tolerating 5 - 7[]. Plants become chlorotic on limey soils[]. They grow well in a hot dry position[], and are very drought tolerant[]. Fast growing[]. Although it prefers a well-drained soil, the plant is tolerant of both drought and wet conditions[].
The plant can be trained and grown against a sunny wall[].
Old specimens sucker very freely, often at considerable distances from the parent tree[]. Plants can be coppiced[].
A very ornamental tree[], there are some named varieties[]. The species is cultivated in S. Europe for ornament, timber and soil stabilization[]. The flowers are very attractive and are often sold in florists[, ]. The violet-like perfume of the flowers can be quite intoxicating on a calm day[].
This species has a symbiotic relationship with certain soil bacteria, these bacteria form nodules on the roots and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby[].

Edible Uses

Flowers - cooked[]. Rich in pollen, they are often used in fritters.

A gum that exudes naturally from the trunk is edible and is used as a substitute for Gum Arabic[]. It is very soluble in water and viscous[, ], but is of low quality[]. Larger quantities can be obtained by tapping the trunk[]. Some species produce a gum that is dark and is liable to be astringent and distasteful, but others produce a light gum and this is sweet and pleasant. It can be sucked like candy or soaked in water to make a jelly.[]. The gum can be warmed when it becomes soft and chewable[].

Medicinal

The bark of all Acacia species contains greater or lesser quantities of tannins and are astringent. Astringents are often used medicinally - taken internally, for example. they are used in the treatment of diarrhoea and dysentery, and can also be helpful in cases of internal bleeding. Applied externally, often as a wash, they are used to treat wounds and other skin problems, haemorrhoids, perspiring feet, some eye problems, as a mouth wash etc[, ].
Many Acacia trees also yield greater or lesser quantities of a gum from the trunk and stems. This is sometimes taken internally in the treatment of diarrhoea and haemorrhoids[].

Agroforestry Uses:

The plant is often one of the first species to invade disturbed land[]. Growing quickly, and fixing atmospheric nitrogen, it quickly creates conditions suitable for other trees to become established. It makes an excellent pioneer species for restoring native woodland, though should only be used within its native range due to the possibility of it invading other habitats. It can also be used to help establish woodland gardens[].
The extensive root system of this plant helps to prevent soil erosion[].
A fast-growing species, it has been used in windbreaks and also to control soil erosion, stabilize hillsides and gullies[].
'Kambah Carpet', a prostrate form of the plant, can be used as a ground cover.

Other Uses

A yellow dye is obtained from the flowers[].
A green dye is obtained from the seed pods[].

An essential oil obtained from the flowers is used as a fixative in high-grade perfumery products[, ].

Tannin is obtained from the bark[, ]. An excellent source of tannins[]. On a 10% moisture basis, the bark contains 19.1% tannin[]. Bark harvested for its tannins should only be taken from mature stems, and only when the sap is rising at the beginning of the growing season - which is when the tannin content is highest and the bark is most easily removed from the wood[].

A gum exudes naturally from the bark and more freely from wounds made into the bark. It is very soluble in water and viscous[, ], but is of low quality[64. It can be used like gum arabic, obtained from Senegalia senegal - gum arabic has a variety of uses, including adding lustre to crape and silk, thickening colours, calico printing, manufacturing ink and as a mucilage[].

The heartwood varies from light-brown to pinkish. The wood has good glueing and pulping properties. Of good quality, it is used for making furniture and items such as clothes pegs, shoe heels and wood wool; and is also used for pulp[]. It produces a high quality pulp suitable for making a range of paper and paperboard products[].
Compared with many other acacias the wood of this species makes a rather poor fuel[].

Propagation

Seed - best sown as soon as it is ripe in a sunny position in a warm greenhouse[].The dried seed of most, if not all, members of this genus has a hard seedcoat and may benefit from scarification before sowing to speed up germination. This can usually be done by pouring a small amount of nearly boiling water on the seeds (being careful not to cook them!) and then soaking them for 12 - 24 hours in warm water. By this time they should have imbibed moisture and swollen - if they have not, then carefully make a nick in the seedcoat (being careful not to damage the embryo) and soak for a further 12 hours before sowing. Sow the seed in Spring in a greenhouse. As soon as the seedlings are large enough to handle, prick them out into individual pots and grow them on in a sunny position in the greenhouse for their first winter. Plant them out in late spring or early summer, after the last expected frosts, and consider giving them some protection from the cold for their first winter outdoors.
Acacia seeds that have matured fully on the bush and have been properly dried have a hard seed coat and can be stored in closed containers without deterioration for 5 - 10 years or more in dry conditions at ambient temperatures. It is best to remove the aril, which attracts weevils and can lead to moulds forming. The arils are easilyremoved by placing the seeds in water and rubbing them between the hands, then drying the seeds and winnowing them[].
Cuttings of half-ripe wood with a heel, mid summer in individual pots in a frame[]. Overwinter in a greenhouse for the first winter and plant out in their permanent positions in late spring or early summer. Fair percentage[].