3. Blue Atlas Cedar

Here's an exotic tree, witness to a time when species from elsewhere were a sign of their owner's good taste and fortune. At the time, we had no idea that these trees of distant origins would be incapable of supporting the local flora.
The study of the interactions between species and their environments led to the notion of biodiversity. Although biodiversity is as old as life on Earth, it was only recognised and studied in the 1980s.