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 pachycarpa is a shrub or small tree with pendulous branches, developing a large crown on favourable sites; it can grow 3 - 6 metres tall[, , ]. 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 seeds are a traditional staple food of the Australian Aborigines. The tree could also be used for fuel and is planted as a shelterbelt. It has potential as an ornamental in arid areas, but this use is limited by the foetid, ‘gidgee’-like odour of the vegetative parts and the flowers[].
The species range is remote and is largely uninhabited. No specific threats were identified . The plant is classified as 'Least Concern' in the IUCN Red List of Threatened Species(2013)[].

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 - Western Australia, Northern Territory.

Habitat

Usually found as individual specimens along drainage lines in clay depressions and clay pans, but also in sandy alluvium along creeks and in sandy loams[, ].

Properties

Conservation Status	Least Concern
Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Shrub
Height	4.00 m
Growth Rate	Medium
Pollinators	Insects
Cultivation Status	Ornamental, Wild

Cultivation Details

Acacia pachycarpa is a plant of hot and arid regions in the tropics of northwestern Australia, where it is found at elevations up to 300 metres. It grows best in areas where annual daytime temperatures are within the range 25 - 37°c, but can tolerate 10 - 45°c[]. It is not tolerant ofany but the lightest frosts[, ]. It prefers a mean annual rainfall in the range 225 - 300mm, but tolerates 150 - 350mm[].
Requires a sunny position[]. Found in the wild in heavier soils, but is tolerant of a wide range, including sandy[, ]. Prefers a pH in the range 6.5 - 7.5, tolerating 6 - 8[]. Established plants are very drought tolerant[].
Requires a sunny position. Found on heavy clay soils as well as sands and loams in the wild, and able to tolerate some salt in the soil[].
A relatively fast-growing tree[].
The plant is considered to be unsuitable for use as an ornamental because the leaves, branches and flowers have an unpleasant smell[].
The plant can be coppiced, producing basal shoots and possibly root suckers after fire[].
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[]. 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[]. A nutritious food, containing 22% crude protein, 8% fat and 57% carbohydrate. The Aborigines of Australia reportedly used them as a staple food[, ]. The seedpods are 7 - 15cm long and 1 - 2cm wide, containing pale brown to black seeds 6 - 9mm long and 5 - 7mm wide[].
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 can be used as a windbreak[].

Other Uses

The wood is heavy[]. No details of usage are given.
The tree has not been used for fuel but has the potential to produce small-sized firewood[].

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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Captcha: if i have 3 bananas, and i eat them all, how many bananas did i just eat?