"The spontaneous vegetation that inhabits our cities is as cosmopolitan as its people and better adapted to their changing environmental conditions than the native species that once grew there.” So says Peter Del Tredici, Senior Research Scientist Emeritus of Harvard University’s Arnold Arboretum and visiting lecturer of Applied Ecology and Planning at MIT, who offers a "radically practical" approach to the urbanization of plants. Those that grow without cultivation in cities and their remarkable ability to flourish in spite of stressful environmental conditions. Cities—including the plants and animals they support—can be considered "novel" ecosystems that not only reflect a tumultuous past but also preview an unpredictable future. "A 'weed' is a politically incorrect term. There is no biological definition of the term weed. It’s really a value judgment.” Nature is coming back to urban areas on its own terms and as Del Tredici explains, "it is an evolutionary process and we need to pay attention to it." Join us for "Urban Nature: Human Nature." Gates open at 5 pm; refreshments available for purchase.