The one tree in Francie's yard was neither a pine nor a hemlock. It had pointed leaves which grew along green switches which radiated from the bough and made a tree which looked like a lot of opened green umbrellas. Some people called it the Tree of Heaven. No matter where its seed fell, it made a tree which struggled to reach the sky. It grew in boarded-up lots and out of neglected rubbish heaps and it was the only tree that grew out of cement. It grew lushly, but only in the tenement districts.
These lines come from the first chapter of the novel, before the reader knows anything at all about Francie or the Nolan family. The author begins the book by describing the setting—and this specific tree—to emphasize the importance that place will play in the novel. The simile that compares the tree to opened green umbrellas is used a few times throughout the book, and describes the tree just as Francie would see it from an upstairs window, looking down. The quote also alerts the reader that class will be an important theme. Unlike almost all material things, the tree is something that poor people have that no rich person can ever attain. The tree grows "only in tenement districts," and the book will focus on the places where the trees grow, and the people who live close to it. The idea that poor people have something that no one else has suggests that there is something special about them. The author uses the Tree of Heaven as a symbol throughout the novel of the lives of poor people, and specifically, of Francie's growth from a child to a woman.