What is an example of symbolism in the novel, All the Crooked Saints?

The black rose symbolizes the dark love Francisco desperately wants from his angry wife, Antonia. Francisco knows that breeding a black rose is almost very nearly impossible. He never manages to grow one in his greenhouse, but Antonia is the one who provides him with one. Her presentation of her black rose comes at a time in the novel when Antonia is letting go of her anger and letting Francisco back into her life.