This was a controversial book when it was published in 1943. I remember my mother disapproved of the book. It would not be controversial now. Regardless it was a best seller and is still widely read to this day. Basically it is the story of Francie Nolan growing up in a poor neighborhood in Brooklyn. The metaphor is the tree , a Tree of Heaven, that grows in the courtyard of the tenement where Francie lives that live on and grows in a very difficult environment. Like the Tree of Heaven, now considered an invasive species, Francie survives and grows strong either in spite of or because of the hardships her family endures during her childhood and teen years. A Tree Grows in Brooklyn is a well written, interesting read.