Literary heritage: the "Loony Tunes" girlfriend of Porky Pig. But with the increasing popularity of all kinds of unusual botanical names, Petunia may be a name we start to hear more of. Perhaps-more-pleasing Petunia alternatives: Petal, Posy, Poppy.
HarryPotter's aunt is named Petunia. She was his mother's sister.
In Caitlin Kittredge's "BlackLondon" series, the female protagonist is Petunia, but she prefers Pete.
Petunia, a tattoo on LittlePete's left forearm depicting a woman in a red dress on TV series The Adventures of Pete & Pete