Acacia is a genus of shrubs and trees belonging to the subfamily Mimosoideae of the family Fabaceae, first described in Africa by the Swedish botanist Carl Linnaeus in 1773.
Many non-Australian species tend to be thorny, whereas the majority of Australian acacias are not. They are pod-bearing, with sap and leaves typically bearing large amounts of tannins and condensed tannins that historically in many species found use as pharmaceuticals and preservatives.
The generic name derives from ακακία (Akakia), the name given by early Greek botanist-physician Pedanius Dioscorides (ca. 40-90) to the medicinal tree A. nilotica in his book Materia Medica. This name derives from the Greek word for its characteristic thorns, ακις (akis, thorn). The species name nilotica was given by Linnaeus from this tree's best-known range along the Nile river.
Acacias are also known as thorntrees, whistling thorns or wattles, including the yellow-fever acacia and umbrella acacias.
The genus Acacia previously contained roughly 1300 species, about 960 of them native to Australia, with the remainder spread around the tropical to warm-temperate regions of both hemispheres, including Europe, Africa, southern Asia, and the Americas. However, in 2005 the genus was divided into five separate genera. The name Acacia was retained for the majority of the Australian species and a few in tropical Asia, Madagascar and Pacific Islands. Most of the species outside Australia, and a small number of Australian species, were reclassified into Vachellia and Senegalia. The two final genera, Acaciella and Mariosousa, only contain about a dozen species from the Americas each.
Acacia seeds are often used for food and a variety of other products.
In Burma, Laos and Thailand, the feathery shoots of Acacia pennata (common name cha-om, ชะอม and su pout ywet in Burmese) are used in soups, curries, omelettes, and stir-fries.
In Mexico the seeds are known as Guajes. Guajes or huajes are the flat, green pods of an acacia tree. The pods are sometimes light green or deep red in color—both taste the same. Guaje seeds are about the size of a small lima bean and are eaten raw with guacamole, sometimes cooked and made into a sauce. They can also be made into fritters. The ground seeds are used to impart a slightly garlicy flavor to a mole called guaxmole (huaxmole). The dried seeds may be toasted and salted and eaten as a snack referred to as "cacalas".
The predominantly herbivorous spider Bagheera kiplingi, which is found in Central America and Mexico, feeds on nubs at the tips of the acacia leaves, known as Beltian bodies, which contain high concentrations of protein. These nubs are produced by the acacia as part of a symbiotic relationship with certain species of ant, which also eat them.
Acacia is listed as an ingredient in Sun Drop, Fresca, a citrus soft drink, RC Cola, Barq's root beer, Full Throttle Unleaded Energy Drink, Strawberry-Lemonade Powerade as well as in Läkerol pastille candies, Altoids mints, Langer's Pineapple coconut Juice, Wrigley's Eclipse chewing gum and M&Ms Pretzel.
Honey labeled under the term 'Acacia Honey' is a type of honey produced by bees from a false acacia known as black locust in North America, but called by the misnomer 'acacia' in Europe, hence this liquid honey which practically doesn't crystallize does not come from true acacias.