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[
Racosperma adsurgens (Maiden & Blakeley) Pedley
Acacia adsurgens is a spreading, multi-stemmed shrub or a small tree that can grow up to 4 metres tall and up to 8 metres across[
, ]. Young plants are often bushy and rounded but become openly branched, sometimes spindly and with an untidy aspect with age. The stems can be up to 10 - 15cm in diameter[
]. Although it produces true leaves as a seedling, llike 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 traditionally harvested from the wild for local use as a food and also has medicinal applications. It has potential for wider use as a food source, is a good fuel crop and can be used for soil stabilization.
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.
Australia - Western Australia, Northern Territories, Queensland
Reddish sandy and gravelly soils, on flat plains and hillsides, commonly in spinifex grassland communities, sometimes with eucalypts; at elevations up to 700 metres[
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Acacia adsurgens is a plant of the warm to hot, semi-arid and arid zones of northern Australia, where it can be found at elevations up to 700 metres. Summers are hot with the mean maximum temperature of the hottest month 36 - 39°c and the mean temperature of the coldest month 5 - 11°c. There is an average of 1 - 11 frosts per year over much of the range. Mean annual rainfall is in the range 65 - 500 mm.
Requires a sunny position in a well-drained soil. The plant grows in the wild mainly in deep, well-drained, infertile, acidic, red sand and sandy loam soils, though it may also occur in skeletal soil in rocky habitats such as gravelly scree slopes[
Acacia adsurgens appears to be a moderately fast-growing but relatively short-lived species. Plants can grow to 100cm tall and commence flowering within 22 months from seed, producing heavy seed crops in good seasons. However, they usually become senescent when about 8 - 20 years old[
Plants have a moderate coppicing ability[
The seeds are usually produced in moderate quantities, with heavy crops produced in good seasons[
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.
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 traditional food for the native Australians who roasted and ground the seeds to a paste prior to consumption[
]. The sweetly-scented pods are 4-12 cm long, 2-3 mm wide, containing very dark brown to blackish, narrowly obloid to obloid-ellipsoid seeds 3.5 - 4.5mm long and about 2mm 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[
The Warlpiri people of Central Australia have used the foliage of this species for medicinal purposes: the phyllodes are boiled and used as a wash for general complaints, or used to smoke babies as a treatment for diarrhoea[
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[
This species has excellent potential for planting as low shelter belts and for sand stabilization[
The heartwood is dark brown; it is clearly demarcated from the narrow band of pale sapwood. The wood is very dense, but is generally only available in small dimensions and so is only used for fuel. It makes an excellent fuel and produces one of the best charcoals in Australia's arid belt[
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[