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:

General Information

Acacia torulosa is a slightly resinous, spreading shrub or a tree with a wide crown; it is usually up to 8 metres tall, but can reach 12 metres[, ]. Although it produces true leaves as a seedling, like 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 seed is a traditional food for the native Australians. They are highly nutritious and the plant has been recommended as a new food crop for arid tropical regions[]. The plant is also used in soil reclamation projects and is grown as an ornamental.

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[].
A noxious dust is given off from the seeds during processing in commercial quantities[].
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 - Queensland, Northern Territory

Habitat

Found usually in alluvial sandy soil, close to streams, on rocky hillsides or near beaches, in eucalypt woodland or mixed shrubland; at elevations up to 350 metres[].

Properties

Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Tree
Height	6.00 m
Growth Rate	Fast
Pollinators	Insects
Cultivation Status	Ornamental, Wild

Cultivation Details

Acacia torulosa is a plant of the semi-arid to moist tropical zone of northern Australia, where it is found at elevations up to 350 metres. It grows best in areas where annual daytime temperatures are within the range 22 - 36°c, but can tolerate 12 - 43°c[]. It is not very frost tolerant. It prefers a mean annual rainfall in the range 400 - 700mm, but tolerates 300 - 800mm, and grows in areas with a long dry season[, ].
Requires a sunny position[]. Requires a well-drained soil, growing well in soils of light to medium texture and tolerating low fertility[]. Prefers a pH in the range 5 - 7.5, tolerating 4.5 - 8[]. Established plants are very drought tolerant[].
The plant is sometimes grown as an ornamental[].
Plants are fast-growing when young and are moderately long lived, usually to 10 - 50 years[].
The plant generally responds poorly to coppicing[].
Although it occupies a wide range of habitats, this species is not very variable morphologically[].
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

Seed - cooked. Tasty[]. It can be eaten in the same ways as other small legume seeds and is also ground into a powder then used as a flavouring in desserts or as a nutritious supplement to pastries and breads[]. The seedpods are 6 - 20cm long and 3 - 6.6mm wide, with dark brown, more or less elliptic seeds 4.4 - 6.5mm long[].
Acacia seeds are highly nutritious and contain around 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. The energy content is high in all species tested, averaging 1480 ±270 kJ per 100g. The 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[].

The ground seed can be used to produce a high quality, caffeine-free coffee-like beverage[].

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 has a deep root system and although it has a broad crown, it casts only a light shade. It has potential for interplanting with traditional crops such as millet, where it will also help to add nitrogen and organic matter to the soil[, ].
The tree has been used in mine-site rehabilitation projects in northern Australia[].

Other Uses

The dark brown wood is tough and strong[]. When obtained from taller specimens, the wood can be used for local construction.
The wood should be suitable for fuel[].

Propagation

The 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.
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[].

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