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Vachellia karroo - (Hayne) Banfi. & Galasso

Common Name Cape Thorn Tree
Family Fabaceae
USDA hardiness 10-12
Known Hazards None known
Habitats Woodland, wooded grassland, coastal scrub, often by rivers and in valleys, from near sea-level to 1,520 metres[308 ]. Found in riverine communities and even in arid environments, where it can do well provided there is an assured supply of groundwater[303 ].
Range Southern Africa, from the Cape as far north as Angola and Kenya.
Edibility Rating    (2 of 5)
Other Uses    (4 of 5)
Weed Potential Yes
Medicinal Rating    (1 of 5)
Care (info)
Tender Well drained soil Moist Soil Wet Soil Full sun
Vachellia karroo Cape Thorn Tree

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Vachellia karroo Cape Thorn Tree
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Vachellia karroo, also known as Cape Thorn Tree, is an evergreen tree in Southern Africa growing about 15 m in height. The crown is rounded and branches fairly low down on the trunk. The bark is red on young branches then becomes dark and rough as the tree matures. The leaves are dark green and finely textured. The yellow flowers are fragrant. The seed pods are narrow, flat, and crescent-shaped. Medicinally used to treat pain in the alimentary canal, rheumatism, convulsions, gonorrhea, syphilis, diarrhea and as an aphrodisiac and emetic. The gum from the plant is eaten as a confectiona. Seeds are roasted and used as a coffee substitute. Cape thorn tree is a pioneer species. The bark and seed pods are sources of tannins. The bark also yields red dye while root bark is used for twine and rope. The wood is suitable for furniture and interior finish of building. It is also an excellent firewood.

Physical Characteristics

 icon of manicon of cone
Vachellia karroo is an evergreen Tree growing to 10 m (32ft) by 12 m (39ft) at a medium rate.
See above for USDA hardiness. It is hardy to UK zone 10. The flowers are pollinated by Insects. The plant is not self-fertile.
It can fix Nitrogen.
Suitable for: medium (loamy) and heavy (clay) soils and can grow in heavy clay soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils and can grow in very acid soils.
It cannot grow in the shade. It prefers dry moist or wet soil and can tolerate drought.

UK Hardiness Map US Hardiness Map


Acacia capensis E.Mey. Acacia hirtella E.Mey. Acacia horrida (L.) Willd. Acacia inconflagrabilis Ger

Plant Habitats

Edible Uses

Edible Parts: Seed
Edible Uses: Coffee  Gum

The gum is eaten as a confection[303 ]. The roasted seeds are used as a substitute for coffee[303 ]. Children chew the sweet thorns[303 ].

References   More on Edible Uses

Medicinal Uses

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Antidiarrhoeal  Antirheumatic  Aphrodisiac  Emetic

A root infusion is taken by local people to treat pain in the alimentary canal, rheumatism, convulsions, gonorrhoea and as an aphrodisiac[303 ]. Root powder is applied to penile sores for treating syphilis[303 ]. A bark decoction is an emetic for treating diarrhoea[303 ].

References   More on Medicinal Uses

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Other Uses

Charcoal  Dye  Fibre  Fuel  Gum  Pioneer  Soil conditioner  Soil reclamation  String  Tannin  Wood

Agroforestry Uses: Universally accepted for use as a rehabilitation plant in degraded sites and dunes[303 ]. It produces a new flush of leaves when the temperatures are highest and before the rains, when there is a great need for shade to reduce soil temperatures[303 ]. It stimulates the development of an understorey of perennials, palatable and nutritious grasses (such as Cenchrus ciliaris, Panicum maximum) through providing them shade, fixing nitrogen and improving soil structure and infiltration[303 ]. A pioneer species with a climax of 40 years, it occupies a successional position between the tropical forest and the bushveld[303 ]. The long flowering season makes this plant a useful tree for apiculture. Bees collect both pollen and nectar from the flowers[303 ]. Large specimens are an indicator of underground water[303 ]. Other Uses A gum is obtained from the stems[46 ]. It resembles gum arabic and is used regionally in southern Africa as a substitute for that gum[46 , 303 ]. It cannot be exported to Europe or the USA because it has not been cleared for toxins[303 ]. Annual production is 25-30 t/ha[303 ]. The bark and seedpods are sources of tannins[46 ]. They impart a reddish colour[46 , 303 ]. The bark contains up to 19% tannins[303 ]. The Nama people of southern Africa extract a red dye from the bark[46 ]. The root bark is used for twine and rope (like in the traditional Nama mat house)[46 ]. The wood is hard, tough and moderately durable, but few trees reach a commercial size, thereby limiting its commercial use[46 , 303 ]. It saws easily; planes to a smooth finish; glues and varnishes well - it is used for furniture and the interior finish of buildings[46 , 303 ]. It is, however, likely to twist in seasoning and is susceptible to attack by borers and fungi[303 ]. Kraft properties have been tested, and it pulps quite easily under standard kraft macro-pulping conditions[303 ]. The wood burns brightly, with very little smoke and no odour[303 ]. It splits easily and once dried does not absorb moisture from the atmosphere. It has calcium oxalate crystals that give its embers high temperatures and make them long lasting. These clean burning traits, ideal for cooking and heating, make it excellent firewood wherever it grows[303 ]. In the coastal dunes of Zululand, South Africa, it is reputed as an excellent charcoal source[303 ].

Special Uses

Food Forest  Nitrogen Fixer

References   More on Other Uses

Cultivation details

Succeeds in subtropical to tropical areas where it is found at elevations from sea level to 1,000 metres[303 ]. It grows best where the mean annual temperature is in the range 12 - 40°c and the mean annual rainfall is between 200 - 1,500mm[303 ]. Mature plants can tolerate some frost[303 ]. Prefers heavy black, hydromorphic cracking vertisols with high pH, or deep alluvial clay-loam soils in river valleys[303 ]. It sometimes does well on shale and even on acid soils[303 ]. Established plants are drought tolerant303]. It competes for space, water and nutrients with pasture grasses, thus replacing them[303 ]. It also regenerates rapidly by means of suckers, aggressively colonising nearby grasslands[303 ]. For these reasons it is included in the national weed list in South Africa[303 ]. Cape thorn tree tolerates drought, fire, frost and termites[303 ]. The flowers are fragrant[200 ]. The species has a mixed mating system. It exhibits a tendency towards out-crossing, as evidenced by the existence of trees that are entirely male. It is zoomophilus, principally insect pollinated because the strong colour of inflorescence and the heavy pollen grains attract insects[303 ]. Isolated plants bear no fruits[303 ]. The plant has an invasive root system, making it unsuitable for planting near buildings or paved pathways[303 ]. Considered to be a good indicator of fertile soils for crops and an indicator of surface or underground water[303 ]. Acacia karroo shows a wide range of variation, but not in such a way as to allow any infraspecific taxa to be recognized[308 ]. 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[200 ].

References   Carbon Farming Information and Carbon Sequestration Information

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Plant Propagation

Seed - soaked in hot water, leave in the water to cool overnight, and then sow the next morning[303 ]. The seeds can be planted either directly into small black nursery bags or in flat seedling trays filled with seedling mix[303 ]. They germinate in 3-12 days[303 ]. In its natural range, A. karroo is reported as being easy to raise from seed and has been planted widely for firewood on experimental plots in South Africa and Botswana[303 ].

Other Names

If available other names are mentioned here

khub, butema, cape acacia, cape gum, cape thorn-tree, cassie piquants blancs, cockspur thorn, deo-babool, doorn boom, epya, gaba, intlaka, isinga, kalagali, kalimela, kaludai, karroo thorn, karroodoring, karroothorn, karrothorn, kikar, leoka, micaia, mimosa thorn, mimosadoring, minga, moko, monalana, monee, mooka, mookana, mormati, moshaoka, mpuka, mubayamhondoro, munenje, munga, mussadzi, muunga, orusu, pahari kikar, preta, sussdorn, singa, soetdoring, sweet thorn, sweet-thorn, udai vel, umnga, umngampunzi, umunga, weissdorn, white thorn, witdoring, ongkauru, gamkhuus, gana, hus, khuub, khuus, kuus.

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Found In

Countries where the plant has been found are listed here if the information is available

Weed Potential

Right plant wrong place. We are currently updating this section. Please note that a plant may be invasive in one area but may not in your area so it’s worth checking.

t competes for space, water and nutrients with pasture grasses, thus replacing them[303 ]. It also regenerates rapidly by means of suckers, aggressively colonising nearby grasslands[303 ]. For these reasons it is included in the national weed list in South Africa[303 ].

Conservation Status

IUCN Red List of Threatened Plants Status : This taxon has not yet been assessed

Related Plants
Latin NameCommon NameHabitHeightHardinessGrowthSoilShadeMoistureEdibleMedicinalOther
Vachellia niloticaGum Arabic TreeTree10.0 10-12 FMHNM224
Vachellia seyalShittim WoodTree10.0 10-12 FMHNDM224
Vachellia tortilisUmbrella ThornTree15.0 10-12 FLMNDM224

Growth: S = slow M = medium F = fast. Soil: L = light (sandy) M = medium H = heavy (clay). pH: A = acid N = neutral B = basic (alkaline). Shade: F = full shade S = semi-shade N = no shade. Moisture: D = dry M = Moist We = wet Wa = water.


Expert comment


(Hayne) Banfi. & Galasso

Botanical References

Links / References

For a list of references used on this page please go here
A special thanks to Ken Fern for some of the information used on this page.

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