The name Acacia is derived from the Greek word 'akis' meaning "a sharp point" and relates to the sharp throne species of tropical Africa and Western Asia that were the only known acacias at the time that the name was published. 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.

Acacias occur on most continents as well as Australia and islands to the north. Australia has the greatest number of acacias with well over 1100 species described so far with a lot more still to come. They occur over a wide area of the continent and, with the eucalypts, provide the dominant vegetative cover.

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. The plants often bear spines, especially those species growing in arid regions. These sometimes represent branches which have become short, hard and pungent, or sometimes leaf-stipules

Acacias vary immensely in size and shape from tiny prostrate plants to small shrubs, medium shrubs and of course to trees, some of them up to 30 or 40 meters tall. Acacias often occur as colonizers of disturbed land, or after fire. Acacia dealbata comes up in the thousands at such times. They have a life span varying from a few up to about thirty years and play an important role in preparing the soil for the longer-lived trees. Acacias fix nitrogen in the soil through the activity of a soil bacterium that inhabits, and forms nodules on their roots. Thus acacias are important components of any woodland.

 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.

Did you know?

• There are over 1,300 species of Acacia
• The average protein content of Acacia seed is between 17 and 27 per cent