The protagonist of "Dr. Heidegger's Experiment" by Nathaniel Hawthorne is, not surprisingly, Dr. Heidegger. He has invited some friends from his youth to his study; they have all endured hardships and woes, primarily of their own making, and the narrator shares this insight with his readers:
Dr. Heidegger and all his foul guests were sometimes thought to be a little beside themselves,--as is not unfrequently the case with old people, when worried either by present troubles or woeful recollections.
That is a nice way of saying that many people wondered if this group was a little bit crazy, and the narrator is obviously preparing us for what is about to happen.
The group has gathered in his curious and old-fashioned study, around a black table in the center of which is "a cut-glass vase of beautiful form and elaborate workmanship." He asks his old friends if they will be participants in an experiment.
But without waiting for a reply, Dr. Heidegger hobbled across the chamber, and returned with the same ponderous folio, bound in black leather, which common report affirmed to be a book of magic. Undoing the silver clasps, he opened the volume, and took from among its black-letter pages a rose, or what was once a rose, though now the green leaves and crimson petals had assumed one brownish hue, and the ancient flower seemed ready to crumble to dust in the doctor's hands.
The old doctor explains that this rose is the one he was to have worn fifty-five years ago when he married Sylvia Ward. The marriage never happened because Sylvia was "affected with some slight disorder,... swallowed one of her lover's prescriptions, and died on the bridal evening." (This is an interesting fact to dwell on in this story, but alas it has little to do with the actual rose.) Now he wants to conduct an experiment and claims that he can make this rose look as fresh and new as the day it was picked more than fifty years ago.
The rose in this story, then, is important to Heidegger because it is both the symbol of lost youth and love and the subject of the experiment the old doctor is about to conduct.