Vachellia is a genus of flowering plants in the legume family, Fabaceae, commonly known as thorn trees or acacias. It belongs to the subfamily Mimosoideae. Its species were considered members of genus Acacia until 2009. Vachellia can be distinguished from other acacias by its capitate inflorescences and spinescent stipules. Before discovery of the New World, Europeans in the Mediterranean region were familiar with several species of Vachellia, which they used as medicine. European names for them were inherited from the Greeks and Romans.
The wide-ranging genus occurs in a variety of open, tropical to subtropical habitats, and is locally dominant. In parts of Africa, Vachellia species are shaped progressively by grazing animals of increasing size and height, such as gazelle, gerenuk, and giraffe. The genus in Africa has developed thorns to defend against being eaten.
Nomenclature
By 2005, taxonomists had decided that Acacia sensu lato should be split into at least five separate genera. The ICN dictated that under these circumstances, the name of Acacia should remain with the original type, which was Acacia nilotica. However, that year the General Committee of the IBC decided that Acacia should be given a new type (Acacia penninervis) so that the ~920 species of Australian acacias would not need to be renamed Racosperma. This decision was opposed by 54.9% or 247 representatives at its 2005 congress, while 45.1% or 203 votes were cast in favor. However, since a 60% vote was required to override the committee, the decision was carried, and a nom. cons. propositum was listed in Appendix III (p.286). The 2011 congress voted 373 to 172 to uphold the 2005 decision, which means that the name Acacia and a new type follow the majority of the species in Acacia sensu lato, rather than this genus. The decision remained controversial following the 2011 Congress.
Description
The members of Vachellia are trees or shrubs, sometimes climbing, and are always armed. Younger plants, especially, are armed with spines which are modified stipules, situated near the leaf bases. Some (cf. V. tortilis, Vachellia hebeclada[Wikidata], V. luederitzii and V. reficiens) are also armed with paired, recurved prickles (in addition to the spines). The leaves are alternate and bipinnately arranged, and their pinnae are usually opposite. The racemose inflorescences usually grow from the leaf axils. The yellow or creamy white flowers are produced in spherical heads, or seldom in elongate spikes, which is the general rule in the related genus Senegalia. The flowers are typically bisexual with numerous stamens, but unisexual flowers have been noted in V. nilotica (cf. Sinha, 1971). The calyx and corolla are usually 4 to 5-lobed. Glands are usually present on the rachis and the upper side of the petiole. The seed pod may be straight, curved or curled, and either dehiscent or indehiscent.
V. vernicosa, or "viscid acacia", in habitat, Far West Texas
Habitat and Distribution
It is widespread in the Arava desert area shared by Israel and Jordan.They are among the few trees native to the area. It was once also widespread in Tel Aviv, but was replaced by less thorny trees with broader canopies, although a few still do remain. Other species of acacia are native to a variety of locales in the Americas, such as the southeastern USA, Mexico, Central and South America. It is also common in African countries such as South Africa, Angola, and Zambia. It also exists in India and Pakistan.
Practical Use, Consumption and Folk Medicine
Vachellia seyal, a vachellia which grows in sub-Saharan Africa, secretes gum arabic, which has been used for thousands of years as a binder for paint. Gum arabic also became integral to the printing industry and lithography, and the advent of photography. It is also used in beverage and food domain, preventing crystallization, and in the medical sector, in the production of vitamins and medication. In South Africa, the flowers of Vachellia karoo are essential to honey production, while the medicinal uses of the tree's thorn include eye and cold treatments to plasters and compresses for wounds.
In the Sahelian acacia savanna, the plant provides shelter and cooling cover to both humans and animals, as well as fuel, fiber, and material for fencing. It also balances the soil, and is a food for both wildlife and livestock. The tannins of the tree are used in the local leather tanning industry. In South Africa, where Vachellia karoo is widespread, the tree has been used for making rafts, sewing needles, and housing for royal Zulu women. Naturalists in earlier times even used the trees prickly barbs to fasten insects which they gathered for their collections.
Vachellia tortilis are well known as acacia in Israel, where the seeds are perforated by seed-beetles, which consume the interior of the seed. The seeds then pass through the intestinal tracts of a variety of both domestic and wild animals, such as goats, ibex, gazelles, and hyrax, where they sometimes germinate. While in the digestive system, the beetles often expire. Seeds which endure may germinate if there is sufficient rainfall.
V. vernicosa, detail of inflorescence
Species list
157 species are assigned to Vachellia as of June 2026.
Vachellia bidwillii (Benth.) Kodela—corkwood wattle, dogwood. "'Waneu', of the aboriginals of Central Queensland; 'Yadthor', of those of the Cloncurry River, Northern Queensland."
↑Austin, Daniel F. (2004). Florida ethnobotany Fairchild Tropical Garden, Coral Gables, Florida, Arizona-Sonora Desert Museum, Tucson, Arizona: with more than 500 species illustrated by Penelope N. Honychurch ... [et al.] Boca Raton, FL: CRC Press. pp.58–59. ISBN9780203491881.
↑Chidumayo, Emmanuel N.; Gumbo, Davison J. (2010). The Dry Forests and Woodlands of Africa: Managing for Products and Services. Routledge. p.25. ISBN9781136531378.
↑Corder, Hugh; Glazewski, Jan; Bleazard, Janice (2009). A Rose is a Rose but is an 'Acacia' an 'Acacia'? Global administrative law: development and innovation. Cape Town: Juta. ISBN9780702181900.
↑"Protected Trees"(PDF). Department of Water Affairs and Forestry, Republic of South Africa. 3 May 2013. Archived from the original(PDF) on 5 July 2010.
