• tropical rainforest,
• temperate rainforest,
• sclerophyllous forests (Schlerophylls are plants which have adapted leathery, hard or spiny leaves) and woodlands (wet and dry),
• mulga scrub,
• savanna and steppe,
• alpine grasslands, and
• deserts.

In all these areas except the rainforests the omnipresent tree is the eucalypt. With over 500 species it is the most common tree in the country. Its species dominate the forests and woodlands of the better watered regions of Australia, while vast areas of the drier country, particularly to the south, are covered by eucalypt mallee scrubs.

Another major species in the Australian landscape is the acacia or wattle tree. There are over 600 species in Australia. In the drier woodlands and semi arid areas wattles are co-dominant with the eucalypts.

Evolution has resulted in species that generally can take advantage of every fall of rain, particularly in desert areas. This results in dramatic flowerings in areas generally considered barren. The Kangaroo Paw and Sturt Desert Pea both flower readily after desert rains.

With the unique variety of birds and insects that are available to pollinate flowering plants, many Australian plants have developed distinctive methods of attracting particular species. These include dramatically coloured flowers, unusual shapes designed to brush against birds or insects as they feed, and abundant supplies of nectar. The Kangaroo Paw, Grevillea, and Hakea are examples of this.

Some Australian trees and plants (for example banksias) produce hard woody fruits and seeds, which not only survive fire but require fire to germinate. Fire also burns back undergrowth. Some species’ seeds are adapted to germinate only in the presence of those nutrients available after a fire’s burning. The presence of eucalypts can also dramatically affect the way a fire burns. The volatile oils in eucalyptus leaves rise above the vegetation in advance of a fire front, and can literally explode, ahead of man-made and natural fire breaks.

The ancient soils which are characteristic of Australia are nutrient-deficient after millennia of leaching without renewal from volcanic activity. In some parts of desert Australia the lack of vegetation is an effect of poor soils rather than lack of rainfall. Salt is also becoming a problem over large areas of land as human use of available water lowers the water table. This further reduces the ability of the soil to provide sustenance for seeds.

Flora in Deserts and Arid Areas

On a larger scale, the Outback is dotted with stands of hardy mulgas and wattles, which superficially resemble scrawny eucalypts but have different leaf structures, as well as scattered groups of bloated, spindly-branched bottle trees, whose sweet, pulpy, moisture-laden cores can be used as emergency stock feed in drought conditions. The similar but far larger boab, found in the Kimberley and northeastern Northern Territory, is thought to be an invader from East Africa. Mallee scrub is unique to the southeastern Outback, where clearing of these tangled, bush-sized eucalypts for grazing has endangered both scrub and those animals who rely on it – the mound-building mallee fowl being the best known.

Mangrove swamps, found along the tropical and subtropical coasts, are tidal zones of thick grey mud and mangrove trees, whose interlocked, aerial roots make an effective barrier to exploration. They’ve suffered extensive clearing for development, and it wasn’t until recently that their importance to the estuarine life-cycle won them limited government protection – though Aboriginal people have always found them a rich source of animal and plant products.

Rainforest once covered much of the continent, although today it survives in only a small portion of its former abundance. Nevertheless, you’ll find pockets everywhere, from Tasmania’s richly verdant wilderness to the monsoonal examples of northern Queensland and the Top End in the Northern Territory. Trees grow to gigantic heights, as they compete with each other for light, supporting themselves in the poor soil with aerial or buttressed roots. The extraordinary banyan and Moreton Bay fig trees are fine examples of the two types. They support a superabundance of plant species, with tangled vines in the lower reaches and orchids, elkhorns and other epiphytes using larger plants as roosts. Palms and tree ferns, with their giant, delicately curled fronds, are found in more open forest where there’s regular water.

Some forest types illustrate the extent of Australia’s prehistoric flora. Antarctic beech or nothafagus, found south of Brisbane as well as in South America, along with native pines and kauri or karri from Queensland and Western Australia, which also occur in New Zealand, are all relict evidence of the prehistoric supercontinent Gondwana. Other “living fossils” include primitive marine stromatolites – algae corals – still found around Shark Bay, Western Australia, or in fossilized form in the central deserts.

As long as you don’t eat them or fall onto the pricklier versions, most Australian plants are harmless – though in rainforests you’d want to avoid entanglement with spiky lawyer cane or wait-awhile vine. However, watch out for the large, pale green, heart-shaped leaves of the stinging tree (gympie) – a scraggly “regrowth” plant found on the margins of cleared tropical rainforest. Even a casual brush delivers an agonizing and prolonged sting; if you’re planning on bushwalking in the tropics, learn to recognize and avoid this plant.