The Voyage of Continent Australiaplanet. The oldest known flowering plants survive in its remnant rainforests and the
marsupials have made the continent their own dominion.
The original Gondwanaland floras were much the same as the Jurassic gymnosperm
forests which were dominated by conifers such as the Huon pines, hoop pines, and the
recently discovered Wollemi pines, with an understory of seed ferns and an abundance
of mosses. However, this was changing with the advance of the flowering plants – a
new type of plant whose flowers and nectar attracted insects which would then spread
the associated pollen. To walk through the cool, damp and dark forests of southern
or Antarctic beech in their high mountain ‘islands’ of the east coast of Australia is
to walk back into the realm of Gondwanaland. Light filters down through the forest
canopy towards the forest floor which is covered by rotting logs, mosses and ferns.
These huge trees with their broad leaves are some of the earliest flowering plants.
Their flowers attracted insects, and later birds and marsupials, which spread their
pollen. This new method of reproduction revolutionized the plant world and as the
flowering plants extended their dominion, so did the early marsupials such as the
pygmy possums, because these flowers offered energy-rich nectar or buds and fruits
to add to their diet of forest floor insects and grubs.
As the continent moved northwards the primordial Gondwanan forests retreated to
be replaced by drier, more open woodlands and grasslands and the old Gondwanan
rainforests only survive now as ‘islands’ along the cool, wet, high ranges of the east
coast of Australia. As patches of rainforest grew short of water the trees dropped their
leaves to reduce transpiration, and more sunlight reached the ground, killing off the
understorey of ferns and mosses which had survived there with little light. As the
rainforest trees died, eucalypts, acacias and casuarinas moved in to replace them.
This caused a gradual change across Australia from rainforest to closed forest, to
open woodlands, to dry eucalyptus scrublands and then to grassy plains. Eucalypts
grow in the forests and scrublands,
acacias grow as wattle trees in the
woodlands, casuarinas on the river
banks, banksias in the heathlands,
and spinifex grows in the wide dry
plains of outback Australia. The
mulga, a common dry country acacia,
dispensed with leaves altogether to
conserve the very limited supply
of moisture. What look like leaves
are phyllodes, flattened stems with
oil glands and restricted numbers
of evaporating pores. The branches
of mulga are usually arranged to
Eastern pygmy possum feeding
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