Seattle Streetscapes: Corner of Harrison Street and Boren Avenue

Downtown Seattle is a delight for those who have an eye for streetscape design. Around each corner, there lies a precedent project waiting to be studied. A short stroll through town hosts a myriad of street treatments ranging form those tailored for residential multi-story complexes, to an urban campus for large international online retailers. 

Corner of Boren Avenue and Harrison Street. Note the wide planting area occupies the same depth as the parking lane. Deep planting beds such as this can support healthier, more diverse street plantings.

Aromatic blooms of Cladrastis kentukea (Yellowwood) stopped me on my tracks as I was walking down Boren Avenue. What a gorgeous tree!

Walking around town, I am drawn to the architectural details of objects that most of us spare not a second glance: how the road meets the curb and sidewalk, how the rain water path is controlled and guided off the street, how plantings are made to thrive in an urban setting. For the next few weeks I will be featuring some of these odd corners of the city, hoping to gain some insight into local designs. We'll be taking a closer look at choice of plant material, construction details, amenity selection, and overall design.

Today we're looking at Cladrastis kentukea, commonly known as American Yellowwood tree. These relatively rare native trees line the end of Harrison Street as it meets Boren Avenue. Although hardy to Zone 4, it is not very common to see these used as a street trees in Iowa.

Good street trees should meet certain criteria, specifically when it comes to impeding visibility for vehicles and obstructing traffic. Large oval or rounded canopy trees can be problematic since they have to be "limbed up" or have their lower branches removed to a height above cars and pedestrians to avoid causing obstructions. This makes them less desirable than trees with narrow, more upright growth habits. Cladrastis kentukea, however, features a rounded crown 30 to 50 feet around at maturity. The specimen shown here is already about 20 feet around; at maturity it is likely to graze the adjacent building. Yet trees don't often reach their full potential in urban settings, so is this a good choice?