In Australia, Eucalyptus are just like having barrels of diesel on the fire front in our bushfires. The oil is highly flammable, and also ensures that Koalas stay drugged up and out of the cities.
They're "pretty" in a brutal sort of way, but make no mistake, they are indeed bioweapons disguised as trees.
Yes, and yet, people insist on growing them as they make for good wood and grow quickly. We had a lot of devastating wild fires in Ecuador in the last years due to drought, and Eucalyptus played a devilish role in that.