Form follows function. Although the phrase is ascribed to modernist architect Louis Sullivan, it has been used since the beginning of the 20th century by practitioners ranging from artists to neuroscientists to cardiologists. The ubiquity of the adage may be ascribed to the wide relevance of its message—that to a certain extent, the shape of a given system is determined by the operational roles of its working parts. Even as the motto has gained popularity, however, it has garnered criticism. In my research, I hold this motto’s proverbial feet to the fire as I consider the relationship between urban trees as an amenity and the form of the city around them.
In doing so, I examine what values the urban forest creates, and to what extent these values are a product of their context. In doing so, I argue that a functionalist narrative of amenity value is overly simplistic. Considering the interrelationships between form and function, I offer, is a more useful approach. To support this notion, I focus on Portland, Oregon, and on trees as an urban amenity. In this respect, I investigate the extent to which trees function as an amenity in providing value for the city around them, and conceptualize the urban forest as a system of trees providing value throughout the city.