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