ACACIA  

Acacia is the common name for plants of the genus Acacia of the legume family, Leguminosae. The genus contains a large number of familiar and useful species. Acacias are known as wattles in Australia, as thorns in eastern Africa, and are sometimes sold by florists as Mimosa in Europe and North America. (The name wattle comes from the use of the bark of this plant for temporary "wattle and daub" dwellings in Australia.)

World climatic zones that have a long, dry winter and a short, wet summer often support a shrubby vegetation known as thorn scrub and savanna. Acacia trees constitute much of the vegetation in such climatic regimes. The trees are characterized by their umbrella shape, with basal branching of the stems; the foliage forms a flattened or curved crown. The flowers, usually yellow, grow in crowded, globose heads or cylindrical spikes. Spines are common, and the Central American bull-horn acacia, A. cornigera, hosts a pulp-eating ant that hollows out its large spines in search of food and then lives in them. Acacias can tolerate long periods of drought and, because of the thorns, survive heavily grazed areas.

Acacias are used as ornamentals in tropical and subtropical gardens, as shade trees, and as indoor plants. Livestock are fed the leaves of some acacias; in Australia and parts of Africa the seeds or pods of other acacias are used by humans for food.

Australians also use acacia wood for railroads ties, wheels, handles, and furniture. Some pods yield a substance used for washing silk and as a shampoo. Gums derived from various species of African acacias include Sudan, or Kordofan, gum; Senegal, or Berbera, gum; sunt gum; and Suakin, or talha, gum. Wattle gum comes from Australia. "Acacia negra" is the name given to the bark of several acacias used in the tanning industry as a source of tannin. Cutch, a brown or olive vegetable dye, is derived from a stem exudate of acacia.