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 tetragonophylla is an intricate, often straggly, very prickly shrub or a tree usually growing 2 - 5 metres tall[, ]. 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 plant is harvested from the wild for local use as a food, medicine and source of materials. It can be used in soil stabilization and restoration projects and can make a particularly effective impenetrable barrier.

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 - all mainland States

Habitat

Widespread in arid and semi-arid areas, growing in a variety of habitats, but often near watercourses or in mulga communities[].

Properties

Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Tree
Height	4.00 m
Growth Rate	Slow
Pollinators	Insects
Cultivation Status	Wild

Cultivation Details

Acacia tetragonophylla is a widespread plant of arid and semi-arid regions in central and southern Australia. It is usually found in areas where the mean annual rainfall is within the range 100 - 450mm[]. The plant also experiences frosts in at least part of its range.
Requires a sunny position and a well-drained soil. Found in the wild on soils that can range from sand to clay, and can be either acidic or alkaline[]. Plants are very drought tolerant[].
Mature plants can be very slow-growing[].
Plants are believed to have a relatively long life-span, probably between 50 - 100 years[].
The seeds of most acacia species can be quickly and efficiently harvested at full maturity without the need for any specialised equipment. Small seed-bearing branches can be cut and beaten on sheets, or bushes can be beaten or shaken directly onto large sheets[].
Ccollecting the pods of this species by hand can present problems due to the prickly foliage (stout gloves are recommended). Gently beating the plants and collecting the pods and seeds on a ground sheet beneath is probably a more efficient way of collection; however, the prickly phyllodes may still cause problems, especially for plants where the foliage extends to ground level and when phyllodes become dislodged with the pods[].
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[]. Usually cooked in their pods[]. 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 up to 10cm long and 4 - 6mm wide, with seeds 4 - 5.5mm 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

Decoctions of the phyllodes and the bark of the root are used traditionally by Northern Territory aborigines for treating superficial skin lesions, for bandaging of fractures of the limbs and to remove warts, while in Western Australia the bark is used as a remedy for coughs[, ].

An infusion made from the cleaned inner bark is consumed as a treatment for coughs[].

The ashes of the wood, with the bark removed, has been used as an antiseptic[].

The leaves are chewed as a treatment for dysentery[].

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:

This species has been recommended for revegetation on a variety of soil types in the Midlands and northern wheatbelt regions of Western Australia. It is regarded as being suited to revegetating drainage lines in these areas. However, it has also been reported that althoughthe plant is commonly used in rehabilitation in the goldfields the results are generally poor[].
The plant is reported to be a useful soil binder in sandy areas[].
With its prickly phyllodes, this species can form a dense, impenetrable barrier. When grown in combination with Acacia colletioides a particularly effective live fence could be produced[].

Other Uses

The reddish brown wood has pinkish stripes and smells of violets when cut. It is close-grained, heavy, hard and tough, but is generally too small for anything except tool handles[, ]. It is used traditionally to make boomerangs[].

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[].