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: Brigalow

General Information

Acacia harpophylla is a tree usually growing 12 - 20 metres tall,, reaching up to 25 metres on the most favourable sites[, ]. The moderately straight bole can be up to 60cm in diameter and, when growing in dense stands, it can be unbranched for up to 15 metres[]. The plant produces suckers and can form thickets[]. Although it produces leaves as a seedling, llike most members of the genus the mature plant does not have true leaves but has leaf-like flattened stems called phyllodes[].
The plant is harvested from the wild, mainly for its timber, tannins and essential oil. It is grown as an ornamental in gardens[].

Known Hazards

The plant is reported to cause 'bribalow itch' a form of dermatitis in humans[].
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

Range

Australia - New South Wales and Queensland.

Habitat

Forms extensive open-forest communities usually on fertile clay and loamy clay[]. It grows best on plains, only rarely being found on hills and ridges[].

Properties

Medicinal Rating
Other Uses Rating
Habit	Tree
Height	15.00 m
Growth Rate	Slow
Pollinators	Insects
Cultivation Status	Ornamental, Wild

Cultivation Details

Acacia harpophylla is a plant of semi-arid to sub-humid areas in the warm temperate to tropical zones of eastern Australia, where it is found at elevations up to 330 metres. It grows best in areas where annual daytime temperatures are within the range 18 - 28°c, but can tolerate 7 - 40°c[]. Mature plants can be killed by temperatures of -8°c or lower, but new growth is more tender and can be severely damaged at -1°c[]. It prefers a mean annual rainfall in the range 450 - 600mm, but tolerates 300 - 700mm[]. It can withstand a dry season of 5 - 7 months[].
Requires a sunny position. Found in the wild on fertile clay soils that can be either acid or alkaline and sometimes are somewhat saline[, ]. Prefers a well-drained soil, but can tolerate occasional inundation of the soil[]. Prefers a pH in the range 5.5 - 7.5, tolerating 4.5 - 8.5[].
A fairly slow-growing tree[].
Seedlings develop a tap root initially and later form an extensive lateral root system concentrated in the upper 25cm of the soil[].
An attractive ornamental tree, providing shade and shelter[].
Seed is produced irregularly, and often at intervals of several years[].
The plant sends up suckers from the roots, especially if the plant is damaged, and can form dense stands[, ].
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

None known

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[].

Other Uses

Produces an extremely viscose gum that is as useful as gum arabic (obtained mainly from Senegalia senegal[].

The essential oil in the flowers has been suggested as a source of perfumes[].
The tree yields a scented wood, which may have potential for use in perfumery[].

Source of a reddish-brown dye that stains wool and cotton[, ].

The bark yields a considerable amount of tanins[]. 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[].

The dark brown wood is very hard, very heavy, strong, elastic and durable, with a strong scent of violets[, ]. It can be used for cabinet work, turnery, rail material, building poles etc[]. It splits easily, making it useful for fencing[]. It is used traditionally to make spears, boomerangs and clubs[].
The wood can be used for fuel and to make low quality charcoal[].

Propagation

Unlike most members of this genus, the seed of this species has a thin, permeable seedcoat not requiring any form of pretreatment before germination. Fresh seed gives a germination rate of 97%[].
Seed viability is lost within 6 - 24 months unless the seeds are stored at subfreezing temperatures[].

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