Not that I needed one, but in today’s NYTimes, Thomas Leo
Ogren discusses street trees and allergies. He notes that Norway maples (there is at least one in the mix above) are one
of the most common trees on the sidewalks of New York—as they are in Buffalo and
I imagine many other Northeastern and Midwestern cities. As a monoecious
species, the NM always produces allergenic pollen, as do male dioecious
species, and these types of trees are more commonly found on city
streets—mainly because pollen creation is not a trait planners tend to
consider. Ogren also says:
Street trees weren’t always as allergenic as they are today.
Back in the 1950s, the most popular species planted in the United States was
the native American elm, which sheds little pollen.
I have many, many friends who suffer from allergies in the
spring; I am sure many of you do as well. It may seem onerous to add yet
another criteria to the many qualities we look for in a street tree, but it was
interesting that many of the trees Ogren recommends are trees that we have been
trying to use more of for other good reasons: his list includes mountain ash (Sorbus
Americana), serviceberry (Amelanchier), female red maple (Acer rubrum), and tulip
tulipifera). They are native, attractive, and at least the first
three are of manageable size.
A thoughtful and—most important—diverse selection of street trees is what’s needed
in all American cities. Unfortunately, that didn’t happen in most of them. All too often block after block features a double row of the same, often problematic, species. And
replacing mature trees that, whatever else their qualities, provide beauty and
shade, is a tough call to make.