Above: Eucalyptus in bloom
Eucalyptus trees are a (some would say unfortunate) recent addition to North America's plantlife. They are native to Australia, but have spread throughout the world, arriving in California, apparently, during the mid-1800s.
It is easy to see how insidious the eucalyptus tree can be. In the park I hiked in yesterday there are many native trees, but where the eucalyptus grow they grow alone, staking out their territory at some distance from the next. I believe this is because they take so much space and water from the ground with their large roots they make it difficult for other trees to grow nearby. And where they grow the trails are crusted with the leaves, pods and bark that the trees shed.
Despite the extensive damage they can do to native ecology, the trees are gorgeous and useful. I regularly grab a freshly fallen leaf as I hike, break it open, and breathe in the strong scent to open my lungs as I begin an uphill trek. This seems to help my mild asthma as much as a remember my inhaler helping when I used it as a child. The towering trees are beautiful from a distance, and each bit of the tree is pretty in its own right: the long and slender leaves, the seed pods and emerging blooms, the bark that peels off of the trunks in large strips.