Most eucalyptus trees are moderately-sized but come to their native land, Australia, and you will be surprised at how tall these trees can grow. Indeed, eucalyptus are one of the tallest trees in the world rivaling the coast redwoods of North America.
Eucalyptus is not a single species. In fact, it's the genus, with more than seven hundred species under it. Nearly all of them are native to Australia. The tallest among them is eucalyptus regnans, colloquially known as mountain ash.