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: Wiry Wattle

General Information

Acacia coriacea is an evergreen shrub or small tree growing from 3 - 10 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 tree is harvested from the wild for its edible seeds. These seeds are highly nutritious, and the plant has been recommended as a new food crop for arid tropical regions[]. It is sometimes grown as an ornamental, where it provides shade and shelter[].

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

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Range

Northern Australia - Western Australia, Northern Territory, Queensland, South Australia, New South Wales.

Habitat

Sand dunes and plains, usually in Acacia scrub and shrubland but with disjunct populations in open eucalypt woodland[]. Flats and very gently undulating plains; along seasonal watercourses in the drier part of its range[].

Properties

Edibility Rating
Other Uses Rating
Habit	Evergreen Tree
Height	5.00 m
Pollinators	Insects
Cultivation Status	Ornamental, Wild

Cultivation Details

A plant of drier areas in the tropics and subtropics of Australia, where it is found at elevations up to 750 metres[]. It grows best in areas where annual daytime temperatures are within the range 24 - 32°c, but can tolerate 10 - 43°c[]. Mature plants can be killed by temperatures of -5°c or lower, though young growth can be damaged at -1°c[]. It prefers a mean annual rainfall in the range 300 - 500mm, but tolerates 200 - 800mm[]. Trees are not hardy outdoors in most of the temperate zone, succeeding only in the mildest areas where frosts are occasional and light - even then they need careful placing and are likely to be killed in excessively harsh winters[].
Prefers a sandy loam and a very sunny position[]. Succeeds in dry soils. Succeeds in any good garden soil that is not excessively limey[]. Most species become chlorotic on limey soils[]. Prefers a pH in the range 6.5 - 7.5, tolerating 6 - 8.5[]. This is one of the most drought-tolerant tropical acacias of North and North West Australia, being able to survive years with no more than 50 mm of rain in 20 days in its native area of distribution. Rainfall in its native habitat varies from 200 to 500 mm. Trees are very tolerant of maritime exposure in their native environment, though they are often severely wind-shaped and can be semi-prostrate[].
In Senegal the tree has reached a height of 3 - 3.6 metres within 7 years[].
Plants can regenerate after fire[].
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[].
This species is superficially similar to Acacia stenophylla which has nerveless, woody, indehiscent, moniliform pods, exarillate seeds, more prominent phyllode nerves and inflorescence with a generally well developed axis[]. Also sometimes resembling Acacia sibilans in phyllode morphology and has sometimes been confused in some regions with Acacia calcicola[].
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. Sweet and nutritious[]. The seed contains about 20% protein[]. The seed ranges from 4 - 10mm long and 4 - 6mm wide. 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[].
The immature green seeds can be cooked and eaten like garden peas[, ]. Sweet and highly palatable[].

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

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

The orange arils may be squeezed in water to make a drink[].

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[].
The plant has a deep root system and 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[].

Other Uses

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

The heartwood is dark brown; it is clearly demarcated from the pale yellow sapwood. The wood has been used for making fence posts, small tools and implements[, , ].
The wood is used for fuel and for making charcoal[]. The plant has many fine branches, making it more suitable for
firewood than for conversion into charcoal[].

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[].