By Christian Kull
One of the key questions of our current research project is how, when, and why the ‘mimosa bush’ or ‘cassie’ tree got to Australia. Acacia farnesiana, also known as Vachellia farnesiana (if you agree with the splitting of the acacia genus) is presumed by many botanists to be native to a broad swath of the Americas, from Bolivia north to Texas. Yet it exists all around the tropical and subtropical world. The first British explorers of interior Australia found it growing all over the interior northern part of the continent. How did it get there, then? How long has it been there? The answer matters, because environmental managers these days want to know if a plant is ‘native’ or ‘alien’, as this has repercussions (for better or worse) on how they approach it.