Properly speaking, melaleuca is a
genus in the family
Myrtaceae (
myrtles).
In Florida, "melaleuca" is used as a general name for a species of tree that was imported from Australia because of its deep thirst. The idea was no less than to drain the Everglades by populating it with a tree with such aggressive propagation and such a great need for water that eventually the whole gosh-darned swamp would just cease to exist.
This plan probably would have succeeded had developers and sugarcane barons not beaten it to the punch. Even so, the melaleuca continues to drink quite a lot of water, and is extremely difficult to remove. You can't burn it at normal temperatures because the fumes are toxic. You can't use it for mulch because it will sprout. And if you haul it off to an incinerator to be safely burned, any part of the stump that remains will begin to sprout again.
In addition to threatening the Everglades and being nearly impossible to remove, the omnipresent melaleuca also triggers severe headaches in those who happen to be allergic to its pollen.
This is a darned good example of the havoc created by introducing foreign species into an ecosystem without regard -- or in this case, with psychopathic regard -- for the effects.