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[].
Closely related to Acacia aulacocarpa, with which it sometimes hybridizes in the wild[].

Common Name: Northern Wattle

General Information

Acacia crassicarpa is a small to medium-sized tree with an open, spreading crown; it can grow up to 25 metres tall with occasional specimens up to 30 metres[, ]. The bole, which is up to 50cm in diameter and sometimes fluted at the base, is often straight and branchless for up to 13 - 18 metres[]. 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 tree is planted for weed control, especially to rehabilitate land infested with Imperata cylindrica[]. The wood is used for firewood, making charcoal, for construction etc[]. This is one of a group of species that have been highly recommended as acommercial wood crop for use in tropical plantation forestry.
Logging is occurring and the timber is actively sought-after. The plant is classified as 'Vulnerable' in the IUCN Red List of Threatened Species(2011)[].

Known Hazards

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 - Queensland, north to Papua New Guinea and Indonesia.

Habitat

Found in a variety of habitats including immediately behind beaches, on the coastal plains and foothills, in the understorey of open forest and in open Eucalyptus forest[].

Properties

Weed Potential	Yes
Conservation Status	Vulnerable
Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Tree
Height	20.00 m
Growth Rate	Fast
Pollinators	Insects
Cultivation Status	Cultivated, Ornamental, Wild

Cultivation Details

Occurs mainly at low elevations in the humid and sub-humid tropics[]. It is found in areas where the mean annual rainfall can range from as low as 500 mm to as high as 3,500 mm, with a dry season of 3 - 6 months[]. The mean minimum temperature of the coolest month is 15 - 22°c, and the mean maximum temperature of the hottest month is 31 - 34°c[310. It does not experience frost in its natural range[].
Found in the wild on a variety of soil types, from calcareous beach sands, yellow earths derived from granite, red earths on basic volcanic rock to alluvial and colluvial soils derived from a variety of parent material[]. Plants appear to be tolerant of salt spray and soil salinity[]. Established plants are drought tolerant[].
The tree has been widely planted in the tropics, often to provide shade on beaches[], and has often escaped and become naturalised[].
This is one of the fastest growing tropical Acacia spp. It appears to maintain active shoot growth almost the year round, although a few months of stagnation may occur in the dry season[].
Under favourable conditions, seedlings grow rapidly reaching 25 - 30 cm tall in 3 - 4 months[].
Flowering starts as early as 18 months after planting, while seed is produced in abundance after 4 years. Seeds mature 5 - 6 months after flowering[].
Plants have attained a mean height of 15 - 23 metres and a mean diameter of 10 - 16 cm in 4 years, outperforming other fast-growing Acacia species including Acacia auriculiformis and Acacia mangium[].
Trees do not coppice well[].
In open situations, the crown is strongly branched and casts a moderate shade[].
Preliminary observations indicate that Acacia crassicarpa is resistant to low-intensity fires[].
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

An edible gum is obtained from the tree[]. This can be used to form a tofee (I assume this is a mis-spelling for toffee and not tofu[]) when soaked in water with honey[].

The roots are cooked and eaten[].

Medicinal

The gum, roots, leaves, bark. pods and seeds have been used by aboriginal Australians in decoction, poultice, tonics or inhalations for the treatment of a variety of ailments including diarrhoea, dysentery, sore eyes, colds, sore eyes and skin conditions[].

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 tree provides shade and can be planted for weed control[]. It is often cited as an effective species for the rehabilitation of land infested with Imperata cylindrica[]. In Papua New Guinea, it is reported to be a very vigorous colonizer of degraded soils following shifting cultivation[].
It could be used for the revegetation and fixation of coastal sand dunes and for shelterbelts[].
The leaves decompose slowly and are useful as mulch[].

Other Uses

The sapwood is pale yellowish-brown and the heartwood golden-brown[]. The wood is hard, strong and durable[, ]. It is used for construction, furniture, flooring, board and boat building[]. It appears suitable for pulping, but more study is required to confirm this use[].
The wood dries out moderately rapidly, burns well and is useful for firewood and for making charcoal, although it sparks at ignition and produces some fly ash and smoke during flaming[]. Its energy value is 22 600 kJ/kg[].

Propagation

Seed - requires pre-treatment to break down the hard coat[]. Pouring a small amount of boiling water over the seeds (which cools down quickly and so does not cook the seed), and then leaving to soak for 12 hours is usually effective, as is making a small incision in the coat to allow water to penetrate. Germination levels of 40 - 80% take place in 6 - 15 days[]. Treated seeds are sown in germination beds, and seedlings are transplanted into polythene bags when they reach the 2-leaf-pair stage. Seeds can also be sown straight into polythene bags. Young seedlings should initially be kept at 50% sunlight, but this can be increased to 70% once they have been established. In general, 3 - 4 months are needed to raise seedlings to a plantable size, 25 cm in height[].
Seeds stored in airtight containers at room temperature retain their viability for several years[].
Cuttings.
Air layering.

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