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 should retain the name Acacia, whilst other sections of the genus should be transferred to other genera. This species is transferred to Senegalia[].

Common Name: White Thorn Tree

General Information

White thorn tree is a fast-growing, deciduous tree growing about 10 - 25 metres tall. The tree has short, hooked thorns, usually less than 1cm long[].
The tree is harvested from the wild as a lesser important but still commercial source of gum, which is edible. It is also used locally as a medicine and source of materials, whilst it also has a good reputation for repelling snakes and crocodiles. The plant is grown as a hedge and also for improving soil fertility.

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

Tropical Africa - drier areas from Senegal to Ethiopia and Eritrea, south to Angola, Zambia, Botswana, Mozambique and the Transvaal.

Habitat

Widespread, it is found in wooded grassland and woodland, usually on colluvial or alluvial clays and loams by rivers and streams at elevations of 50 - 1,460 metres[].

Properties

Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Deciduous Tree
Height	15.00 m
Growth Rate	Fast
Pollinators	Insects
Cultivation Status	Wild

Cultivation Details

The white thorn tree grows in tropical areas at elevations from 200 - 1,800 metres[]. It prefers areas where the mean annual rainfall is in the range 300 - 1,000mm[].
Prefers sites with a high groundwater table, indicating eutrophic and fresh soils[]. Prefers alluvial soils with a good mix of clay and sand, though it occasionally prospers on stony slopes and compacted soils[].
Young plants have a fast rate of growth[].
Like most acacias, flowering depends highly on the rains. The cream-white, sessile flowers are inserted in spikes up to 15 cm long. They are produced together with new leaves. After pollination by insects, straight fruits with distinctly narrow, thickened margin are developed within 6 months, fruits are tapered on both ends. When mature the pods turn greyish-brown. The seeding period can be observed approximately 6 months after flowering[].
Plants can be coppiced and pollarded[].
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

A gum obtained from the stems is eaten[].
This species is a lesser source of gum arabic, which is more commonly obtained from A. Senegal[]. Gum arabic is used as follows:-
The resin obtained from the trunk is important in the food industry, where it is used as an emulsifier, stabilizer and flavour fixative[]. It is also used as an additive (E414) that retards the crystallization of sugar[]. It is found especially in products such as chewing gum and confectionery[].
The resin is harvested after the rainy season by scraping it off the trunk and branches from which it oozes[]. Unhealthy trees tend to give higher yields and incisions are sometimes made into the bark in order to increase yields[].

The ashes of the burnt wood are used as a salt substitute[].

Medicinal

The plant (part not specified) is used to make an infusion in which to bath children who are restless at night[].

The roots are tonic and also used as an antidote for snake bites. They are also used in the treatment of venereal diseases[].

A decoction of the bark is used in the treatment of dysentery and gastro-intestinal disorders[].

The leaves are dried then pounded into a powder, which is rubbed into heads of children who are suffering from head sores[].

Agroforestry Uses:

With its ability to fix atmospheric nitrogen, it is planted to stabilize river banks and to improve the soil[].
The plant is sometimes grown as a living fence[].
The presence of the tree in the wild is said to be a good indicator that the land is suitable for growing tobacco and cotton[].

Other Uses

A gum obtained from the trunk is a minor source of gum arabic, more commonly obtained from A. senegal[]. It has a variety of uses, including as an adhesive, adding lustre to crape and silk, thickening colours, calico printing, manufacturing ink and as a mucilage[, ].

The bark and the seedpods are sources of tannins[].
Chips of the heartwood are a source of tannins and dyestuffs[].

The smell of the tree is a useful repellent against snakes and crocodiles[].

The heartwood is red with blackish streaks; the sapwood white. The wood is hard, durable and termite resistant. It is difficult to saw or plane, but easy to polish. It is used for posts, poles, handles, wheels, farm tools, carving etc[, , ].
The wood burns well, but the thorns make it difficult to handle[, ]. It is used for making charcoal[, , ].

Propagation

Seed - requires pre-soaking or scarification. To scarify, the seed coat should be nicked at the distal (cotyledon) end using a sharp tool like a scalpel, knife or nail clipper[]. Large quantities of seeds should be treated by pouring boiling water on them in a vessel. Then the seeds should be left for 24 hours in the water as it cools[]. Under ideal conditions, the seeds germinate within 10-21 days[]. The expected germination rate of mature, healthy and properly treated seed is 60-90%[].
Mature and properly dried seeds can be stored in airtight containers at room temperature for at least 1 year, and at 10c for several years so long as the seed is not attacked by insects[].

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