channel rain down the trunk to masses of fine root hairs in the soil that can capture the
water which would normally evaporate before it could soak deep into the soil.
The Australian eucalypts proved very versatile, evolving into a wide variety of
trunks, leaves, flowers, fruits and growth habits. This diversity allows the eucalypts
to thrive from the coldest alpine regions to the hottest deserts that occur across the
Australian continent. There are about 700 species of eucalypts and around 1000
species of wattles found in Australia and New Guinea.
The Proteaceae are a Gondwanan species which can be found in Southern Africa,
Australia and South America. These were among the earliest flowering plants, and
the better known species amongst them such as the banksias and grevilleas have
adapted to arid and fire-affected habitats. It is significant that the greatest number of
banksia species occur in southern Western Australia and closest to where they occur
in Southern Africa before the continents split apart. Many of the ancestral species are
still found in the tropical rainforests, and the tropical species Banksia dentata occurs
across Northern Australia, New Guinea and on the island of Aru in Indonesia.
The other dominant Gondwanan flora are the acacias or wattles and there are
more species of these in Australia than any other genus. The acacia also extend to the
subtropics of the northern hemisphere, but of the approximate 1300 species around
1000 of them are native to Australia. The flowers can be balls or spikes varying in
colour from almost white, through pale yellow, to a deep gold. It is said that there is a
wattle in flower somewhere in Australia on every day of the year. Their golden flowers
gladden the heart of every Australian, and no other plant lifts their spirit and sense of
national pride more than the sight of a group of wattles in golden bloom.
The melaleuca is a genus of plants that include paperbarks, honey myrtles and tea-
trees. Their flowers generally occur in groups, forming a ‘head’ or ‘spike’ resembling
a brush used for cleaning bottles, containing up to eighty individual flowers. They
are superficially like banksia species, which also have their flowers in a spike, but the
structure of individual flowers in the two genera are very different.
The soils of Australia are the poorest and most fragile of any continent, its rainfall
is the most variable, and its rivers the most ephemeral. It has become a harsh land
and the conservation of moisture became the hallmark of Australia’s plants and
animals. The ancestral Gondwanan flora evolved defences such as hard, spiny, or
thick leathery leaves to conserve moisture. It is the eucalypts that are best adapted to
the arid conditions and nutrient deficient soils and no other comparable area of land,
and in this case a complete continent, is so completely characterized by a single genus
of trees. Almost half of Australia’s trees and shrubs belong to just two families – the
Myrtaceae which includes the eucalypts, tea-trees and bottlebrushes, and the Acacias
or wattles. Grass grows in abundance on the interior plains of Australia. The explorer
Thomas Mitchell, when seeing these vast plains for the first time, considered them
beautiful and imagined the millions of sheep that would soon be grazing on these
16 Where Australia Collides with Asia
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