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 kempeanum (F.Muell.) Pedley
Acacia kempeana is a spreading shrub or a tree with a rounded crown; it can grow up to 5 metres tall. The single trunk usually divides into two at around 50cm from the ground[
]. 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 plant is an important food source for native Australians, who also used it for medicine and as a source of materials.
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 - northern Western Australia, Northern Territory, South Australia, Queensland
Widely distributed in arid areas, where it occurs usually on stony hillsides or in coarse textured alluvial soils; often abundant in mulga woodlands on red sandy loam plains[
]. Often found along seasonal watercourses[
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Acacia kempeana is a wide-spread plant of arid regions in Australia, ranging from the warm temperate zone to just entering the tropics.
Requires a sunny position and a well-drained soil. Found in the wild in stony loam or clay-loam soils, often on granite[
The plant probably flowers whenever temperature and soil moisture are high[
Although top-killed by fire, the plant has been recorded to resprout from the roots following fire or mechanical damage to top growth, especially when growing on shallow, granitic soils[
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[
Acacia kempeana belongs to a taxonomically complex small group of species, including Acacia adsurgens, Acacia atkinsiana, Acacia kempeana, Acacia rhodophloia and Acacia sibirica. At least some of these are believed to hybridize[
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[
]. The seedpods are 2 - 7cm long and, 8 - 16mm wide, with very dark brown to black, obloid to obloid-ellipsoid seeds 3.5 - 4mm long[
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[
An edible gum exudes from the trunk and branches[
The phyllodes and inner bark from the roots were used traditionally for medicinal purposes[
]. No more information is given.
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[
The stem and roots were used traditionally to fashion fighting and fish spears[
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[