Eucalyptus in southern California; railroads thought they'd be great for building ties out of, they're not, and they're extremely flammable and explode.
I always heard that burning eucalyptus wood was toxic, but now i'm wondering if someone got their signals crossed because pressure treated wood and i think creosote treated wood are toxic when burned, too? I heard it as a teen, at school they took down a couple 100' eucalyptus and said we couldn't have a bonfire because of that reason.