Flowers in a hospital room were once thought to be unhealthy or fatal. This was a notion of the Victorians who believed that picked flowers decomposed to such a degree that they made the air unfit to breathe, causing illness and even death.
To illustrate this point the Victorians concocted a morality story, called "The Revenge of the Flowers", about two young girls who took a nap after picking flowers all afternoon. While they slept the spirits of the flowers asked why why the girls had killed them and then breathed decomposing, noxious breaths into the sleeping girls' faces until the two were dead. The last line reads: "The flowers are avenged."