One of the greenest cities in the US, Portland, Oregon, is a great place to learn about plants. From the sprawling "forest in the city"--Forest Park--to tiny Mill End Park--the fabled smallest park in the world--there are numerous sites in which to get better acquainted with local plants like the state wildflower, Oregon Grape, and the state tree, Douglas-fir. It is through the intimate study of plants that so many of us forge deeper and more meaningful...