Answer:
He needed the purple flower because his daughter Beatrice's existence depended on the aroma of the flower.
Explanation:
Nathaniel Hawthorne's Rappaccini's Daughter is a short story about a famed doctor and his special garden of flowers. But more beautiful than the flowers is his daughter who seemed to be brought up by the very plants and hardly venture out anywhere else. The story focuses on the evils of the father that led to the death of the daughter.
While tending to his numerous plants in the garden, Dr. Rappaccini had to use a glove to protect himself from them. But in particular, there were "purple blossoms, each of which had the luster and richness of a gem; and the whole together made a show so resplendent that it seemed enough to illuminate the garden, even had there been no sunshine." Such was the radiance and beauty of the flower that it captured Giovanni, the protagonist's attention. And the purple flower is the lifeline of Beatrice, whose very survival rests upon the aroma, "perfume" of that flower.
