Boxwood

Walking to work this morning across the Seattle Center grounds I noticed many of the trees were enclosed in neat little boxes. Some of the boxes were closed, some were open on one side as these are. Some of the trees are young and newly planted, some are many years old. Clearly they are to protect the trees and may be in preparation for the Bite of Seattle. But the effect was kind of funny. As though the trees had run into phone booths. Phone booths? What are those?