Acacia pachycarpa

Acacia pachycarpa is a tree or shrub belonging to the genus Acacia and the subgenus Juliflorae that is endemic to central and western parts of northern Australia. The Walmajarri people of the Paruku IPA in the Kimberley call this wattle Parrayari.

Description

A shrub or small tree. It grows 5 m tall. There are prickles along the stem. The leaves are twice divided and there are 8-18 pairs of pinnae. There are up to 50 pairs of pinnules on each pinnae. The flowers are yellow. They are in large clusters at the ends of branches. The pods are flattened.

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 Uses

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.

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.

Distribution

It is a tropical plant. It grows in Western Australia. It grows on sandy soils. It needs a well drained sunny position.

Where It Grows

Australia*,

Cultivation

It is grown from seed.

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.

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. The plant can be used as a windbreak.

Notes

There are about 1,350 Acacia species. Over 1,000 occur in Australia. Also as Mimosaceae.

Nutrition

Synonyms

References (6)

• Brand, J.C. & Cherikoff, V., 1985, In Plants for arid lands. Kew.
• Doran, J.C., & Turnbull, J.W. (Eds), 1997, Australian Trees and Shrubs: species for land rehabilitation and farm plantings in the tropics. ACIAR Monograph No 24. p 198
• Elliot, W.R., & Jones, D.L., 1982, Encyclopedia of Australian Plants suitable for cultivation. Vol 2. Lothian. p 93
• Orr & Hiddins, 1987,
• Paczkowska, G . & Chapman, A.R., 2000, The Western Australian Flora. A Descriptive Catalogue. Western Australian Herbarium. p 318

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