Ailanthus altissima (Tree of Heaven) is a common tree of cities. When I talk to people about it I often mention it is the tree featured in Betty Smith’s A Tree Grows in Brooklyn. People are generally surprised to know this tree, by now a well-known invasive, is the subject of this well-loved book. Tree of heaven is ubiquitous in cities, I first became familiar with its ways in Newark, NJ and then saw it all around Philadelphia when I started working in the area. Found in nearly every vacant lot or fallow area, it is considered invasive and ecologically problematic. It is also the host plant for the troublesome spotted lanternfly. This is the weed tree of the city I am familiar with, this is not, however, the tree pictured above.
Perhaps you read the Betty Smith novel A Tree Grows in Brooklyn. {{Spoiler alert}} The tree in the story was an Ailanthus altissima or Tree of Heaven. This tree is known for its ability to thrive in even the harshest of conditions, hence its use as a metaphor for the strength and tenacity of the main character in the book.
“There’s a tree that grows in Brooklyn. Some people call it the Tree of Heaven. No matter where its seed falls, it makes a tree which struggles to reach the sky. It grows in boarded-up lots and out of neglected rubbish heaps. It grows up out of cellar gratings. It is the only tree that grows out of cement. It grows lushly…survives without sun, water, and seemingly without earth. It should be considered beautiful except that there are too many of it.” Betty Smith, A Tree Grows in Brooklyn
The “ghetto palm” (as my inner-city high school interns once described it to me) has become a bit too successful dominating roadsides and vacant lots in all but 6 of the states. Introduced from China as an ornamental plant Ailanthus was planted widely throughout the Northeast in the first half of the century. It fell out of favor with the horticultural crowd but despite its lack of popularity continued to insert itself into devoid and neglected areas of our landscape. In his book Wild Urban Plants of the Northeast Peter Del Tredici asks us to take a different look at these weed plants colonizing waste spaces. He suggests that these “weedy” and “spontaneous” plants benefit the cities by creating forests and the ecological benefits associated with forests, at no cost to the residents. Hmmm. Del Tredici says these are as important part of the urban landscape as the native plants restricted to protected natural areas and the highly maintained cultivated gardens on display throughout the city.
I am still digesting this point of view as it flies in the face of everything familiar to me. While I appreciate the sentiment, science and statistics, it is still hard for me to promote the embrace of invasive, weedy plant species to the detriment of native plants and the wildlife they support. As I continue to consider and explore this topic, I visit those highly manicured cultivated garden spaces that are also an important part of the fabric of a city. This trip takes me to Brooklyn.
HORT travels 