Acacia sophorae (Labill.) R.Br., is treated here as a smaller growing, maritime subspecies of Acacia longifolia and is included in this record. However, some authorities recognize it as a distinct species[].
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: Sidney Golden Wattle

General Information

Acacia longifolia is an evergreen shrub or small tree, ranging in size from a prostrate shrub when growing in poor soils and in maritime exposure to a tree 7 metres or more tall. The open, spreading crown can range from 1 - 25 metres wide[, , ]. Although it produces true leaves as a seedling, llike most members of this section of the genus, the mature plant does not have true leaves but has leaf-like flattened stems called phyllodes[].
The tree is a traditional food source of Australian Aborigines and is also used in the growing Australian Bush foods industry. It is a very ornamental plant and is often cultivated in gardens from the warm temperate zone to the tropics.
Acacia longifolia has been deliberately introduced in various countries, mainly for dune stabilization and soil improvement. It is recognized as an aggressive invasive weed in parts of its native range in Australia, and in some of the countries where it has been introduced; such as in South Africa, Spain and Portugal. It has a prolific seed production, and fast growth, facilitating its spread in suitable habitats[].

Known Hazards

The seed of many Acacia species, including this one, is edible and highly nutritious, and can be eaten safely as a fairly major part of the diet. Not all species are edible, however, and some can contain moderate levels of toxins[]. Especially when harvesting from the wild, especial care should be taken to ensure correct identification of any plants harvested for food[].
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, Queensland, Southern Australia, Tasmania, Victoria.

Habitat

Sandy soils mainly by the coast[]. Grows in a wide range of sclerophyll communities (heathlands to woodlands and tall forests), usually on sandstone and basalt- or granite-derived soils[].

Properties

Weed Potential	Yes
Edibility Rating
Other Uses Rating
Habit	Evergreen Tree
Height	5.00 m
Growth Rate	Medium
Pollinators	Bees
Cultivation Status	Ornamental, Wild

Cultivation Details

Sidney Golden Wattle is a plant of the warm temperate zone, though it is also often cultivated in tropical regions, especially at moderately high elevations[]. Young plants are very sensitive to frost, though become hardier as they grow older with mature specimens able to withstand temperatures down to about -10°c for short periods[]. Plants will often resprout from the base if they are cut back by cold weather[].
Prefers a sandy loam and a very sunny position.[, ]. Succeeds in any good garden soil that is not excessively limey[]. This species is fairly lime-tolerant[, ]. Succeeds in a hot dry position[] and in poor soils[]. A fairly wind resistant tree, growing well in maritime areas[, , ]. Tolerates some salt in the soil[].
Acacia longifolia has been deliberately introduced in various countries, mainly for dune stabilization and soil improvement. It is recognized as an aggressive invasive weed in parts of its native range in Australia, and in some of the countries where it has been introduced; such as in South Africa, Spain and Portugal. It has a prolific seed production, and fast growth, facilitating its spread in suitable habitats[].
Dislikes root disturbance[].
A very ornamental plant, it is fast-growing but fairly short-lived[, ].
The flowers are scented of violets[].
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. The flowers have a violet-like fragrance[].

Seed - roasted[, , , ]. Starchy[]. Rather small and fiddly to gather[]. The pods are rather variable in length, but can be up to 15cm long containing seeds up to 6mm long[]. Acacia seeds are highly nutritious and contain approx 26% protein, 26% available carbohydrate, 32% fibre and 9% fat[]. The fat content is higher than most legumes with the aril providing the bulk of fatty acids present[]. These fatty acids are largely unsaturated which is a distinct health advantage although it presents storage problems as such fats readily oxidise[]. The mean total carbohydrate content of 55.8 + 13.7% is lower than that of lentils, but higher than that of soybeans while the mean fibre content of 32.3 + 14.3% is higher than that of other legumes such as lentils with a level of 11.7%[]. The energy content is high in all species tested, averaging 1480+270 kJ per 100g[]. Wattle seeds are low glycaemic index foods. The starch is digested and absorbed very slowly, producing a small, but sustained rise in blood glucose and so delaying the onset of exhaustion in prolonged exercise[].

Seedpods - roasted[]. The pods are up to 10cm long[].

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 extensive root system of this plant helps to prevent soil erosion[]. It is used on sandy soils and steep banks[]. The subspecies Acacia longifolia sophorae is useful for sand stabilisation on beaches, where it grows quickly, binding sand and fixing nitrogen with its roots, as well as providing shelter. This makes it a very useful plant to help re-establish native sand-dune plant communities[].
Trees are planted as a screen in Australia[].
This species is often grown as a rootstock for grafting lime-intolerant members of the genus[].

Other Uses

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

The bark contains around 12 - 19% tannins[, ]. It can be used for waterproofing and preserving ropes and sails[]. 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 white wood is light in weight, hard, tough and durable. It is used for tool handles etc[, , ].

Propagation

Seed - best sown as soon as it is ripe in a sunny position[]. Stored seed should be scarified, pre-soaked for 12 hours in warm water and then sown. The seed germinates in 3 - 4 weeks at 25°c[]. As soon as the seedlings are large enough to handle, prick them out into individual pots and grow them on in a sunny position until large enough to plant out.
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, in individual pots[]. Fair percentage[].

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