Adding to Scoby2's answer, Carl, "mallee" is the term for any of many different euclayptus trees which have adapted to harsh desert or near-desert conditions by shrinking (most are between perhaps 2 metres and 6 metres tall, typically around 3-4); developing a giant lignotuber (swollen root, bit like a carrot or a turnip); having many small trunks instead of one big one; and adapting to or even encouraging fire.
The huge root stores a lot of energy; when a fire comes along, the tops burn off and the landscape looks as though everything has been killed. All the other vegetation regenerates from seed, but the mallees simply grow new tops, using the energy stored in that gigantic root system. This allows them to regenerate faster and out-compete normal plants in the race to reestablish.
^ Spinifex mallee: Hattah, NW Victoria.
Many mallee species also have developed bark that peels in long ribbons: this burns readily and blows around in any wind, helping to spread a fire. Mallees, in other words, are a bit like the Tea Party - they reckon that if you destroy everything, they'll be the only ones with the resources on hand to recover first and take over the wreckage. And, over vast areas of this huge country, that's exactly what they have done. At a wild, wild guess, 10% of the continent is covered in mallee. (Mulga - an alternative strategey practiced by various desert-loving Acacia species - is even more successful, but mulga is a topic for another day.)
^ Malle bark, Wongan Hills, SW WA.
By the way, "Mallee" (with a capital "M") is also the name of a district in Victoria - the large north-western part of the state (presumably named after the vegetation). Over the border in South Australia, the equivalent district is the Murray Mallee. (South Australians pay a lot of attention to the Murray 'coz it's the river they've got worth mentioning, unless you count the Cooper.)