Part 1 of Essay
Although only a dozen plant families are unique to , there are 530 unique genera and many unique species within these genera. As the n fragment of prehistoric Gondwanaland drifted north, its ancient flora became the basis for the present plant systems. Increasing aridity modified this vegetation, giving much of it hardened ....

Part 2 of Essay
.... of vegetation, communities dominated by the tall, straggly eucalyptus trees, is the most ubiquitous, forming a wide, concentric band around the desert core. Of the 500 species, two or three typically form a mosaic in one locality and intermingle with other plant associations. Eucalyptus trees are classified according to their bark types--hence the names stringybark, ironbark, bloodwood, and smoothbark (the gums that shed their outer bark annually). The most widespread is the river red gum. Mallee eucalypts survi ....