Acacia acradenia

Acacia acradenia, commonly known as Velvet Hill wattle and silky wattle, is a species of flowering plant in the family Fabaceae and is native to northern and central Australia. It is a spindly shrub or tree with elliptic or narrowly elliptic phyllodes, spikes of orange or golden flowers and linear, crustaceous pods. The Nyangumarta peoples know it as walypuna the Alyawarr call it ampwey, the Jaminjung and Ngaliwurru know it as mindiwirri, the Jaru as binbali or gundalyji, the Kaytetye as ampweye or arwele and the Warlpiri as ngardurrkura.

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

Indigenous Australians use the species as a food source, water source, shade or shelter and to make weapons and implements.

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 suits a warm dry climate. It requires a well drained soil in a sunny position. It can grow in arid places. It is best with a temperature between 24-34°C and an annual rainfall between 400-800 mm. It is best with a soil pH 7-8.

Where It Grows

Australia*,

Cultivation

Acacia acradenia is a plant of arid and semi-arid subtropical to tropical climates of northern Australia. Requires a sunny position and a well-drained soil. The plant has considerable potential as an ornamental in drier regions. Plants can flower all year round. Plants are usually killed by fires, but regenerate freely by means of seeds. 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 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.

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 stems were traditionally used to make spears.

Notes

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

Also Known As

Ampwey mpwiya, Ngardurrkura ngarulkurra

References (11)

• Cherikoff V. & Isaacs, J., The Bush Food Handbook. How to gather, grow, process and cook Australian Wild Foods. Ti Tree Press, Australia p 188
• ecocrop.fao.org
• Elliot, W.R., & Jones, D.L., 1982, Encyclopedia of Australian Plants suitable for cultivation. Vol 2. Lothian. p 12
• Iconogr. Austral. Acacia 11: t. 4. 1888
• Kenneally, K.E., Edinger, D. C., and Willing T., 1996, Broome and Beyond, Plants and People of the Dampier Peninsula, Kimberley, Western Australia. Department of Conservation and Land Management. p 128

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