What does the title, White Oleander have to do with the story?

Ingrid is depicted as a white oleander (source of poison), and her daughter should know how to survive beside this poisonous plant. Ingrid says that Astrid’s house is Ingrid, but it is not a stronghold, where Astrid can feel safety. This house even does not have a roof; all walls are in the thorns, the icy draft is walking through the empty rooms. Astrid is not so important for her mother, but if Ingrid tries to add Astrid to the list of valuable things, she will break or destroy her. From the point of view of morality, Ingrid is cruel and selfish. She poisons life of her daughter. It is a catastrophe to have such mother; it is a personal apocalypse to love such mother.