Basil
In Boccaccio's Decameron a memorably morbid tale (novella V) tells of Lisabetta, whose brothers slay her lover. He appears to her in a dream and shows her where he is buried. She secretly disinters the head, and sets it in a pot of basil, which she waters with her daily tears. The pot being taken from her by her brothers, she dies of her grief not long after.  Boccaccio's tale is the source of John Keats' poem Isabella or The Pot of Basil.  A similar story is told of the Longobard queen Rosalind.